isotopic mass of m & ms - ms. francois' ap chem...

Name: ________________ School Year: ____________ Class Period: ___________

© Ms. Francois, 2015

The Sweet Side

of Chemistry

AP Chemistry Lab Manual

2

Table of ContentsLab #

Experiment Page #s

Date Teacher Signatur

e1 Lab Safety & Equipment2 Chromatography of Skittles3 Densities of Unknown Elements

(Guided)4 Isotopic Mass of M & Ms5 Building 3D Models of Molecules6 Penny Surface Tension &

Intermolecular Forces (Guided)7 Ionic vs. Covalent Bond Stations8 Construction of Isomers9 % Composition of Sugar in Gum

(Guided)10 Making Ice Cream:

Freezing Point Depression11 Conservation of Mass12 Types of Reactions13 Heating Curve Plot14 Gas Laws (Guided)15 Vapor Pressure & Evaporative

Cooling16 Acidity of Candy17 Titration18 Electrolysis19 Half Life20 Bonus: Beer’s Law—Absorbance of

Gatorade

Lab 1: Lab Safety

Date of Lab: ____________________________________

Question: How do I conduct lab safety experiments safely?

Introduction: Experimenting in the science lab is safe if you are careful! Each student must assume responsibility for the safety of themselves and those around them.

Pre-Lab Quick Write: Why do you think safety rules are so important?

_________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

Activity #1: Safety VideoTo prepare yourself to work safely in the laboratory, first pay attention to the video shown in class. Jot down four safety rules that catch your attention in the space below.1. ______________________________________________________________________________________________

__________________________________________________________________2. ______________________________________________________________________________________________

__________________________________________________________________3. ______________________________________________________________________________________________

__________________________________________________________________4. ______________________________________________________________________________________________

__________________________________________________________________

Activity #2: Reviewing Lab Safety Rules Read over the following safety rules. Make sure you understand and follow each rule. Ask your teacher to explain any rules you do not understand. These rules will also be listed in your lab safety contract that will need to be signed by your parent and you.

PREPARE FOR LABORATORY WORK Study laboratory procedures prior to class. Never perform unauthorized experiments. Keep your lab bench organized and free of apparel, books, and other clutter.

DRESS FOR LABORATORY WORK

3

Tie back long hair. Wear shoes with tops. Wear safety goggles during all laboratory sessions.

AVOID CONTACT WITH CHEMICALS Never taste or "sniff" chemicals. When heating substances in a test tube, point the mouth away from people. Never carry dangerous chemicals or hot equipment near other people.

AVOID HAZARDS Use caution when handling hot glassware. Turn off burners when not in use. Do not bend or cut glass unless appropriately instructed by teacher.

CLEAN UP Consult teacher for proper disposal of chemicals. Wash hands thoroughly following experiments. Leave laboratory bench clean and neat.

IN CASE OF ACCIDENT Report all accidents and spills immediately. Place broken glass in designated containers. If chemicals get in your eyes, wash them for at least 15 minutes with an eyewash.

Activity #2: Lab Safety Rules continued: Answer the following questions about different lab safety rulesLab Directions:

Suppose you are going to begin a scientific investigation. What should be one of the first things everyone in your group should do?

Lab Area SafetyImagine this is your group’s lab area. What is wrong here?

What might happen if your lab group had such a cluttered lab area?

Lab Dress CodeWhat do you think is the proper clothing to wear when we

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conduct laboratory investigations? (include hair, shirts, jewelry, shoes)

Glassware and Sharp Object Safety

What should you do if you break any of the glassware?

Should you use the flask above? Why or Why not?

Chemical Safety, Part 1

If this substance had been poisonous, what might have happened if you sniffed it?

What is the proper way to smell a substance in the lab?

Chemical Safety, Part 1

If you spilled a chemical, what would you do?

Clean Up, Part 1

What should you always remember to do before leaving the lab?

Clean Up, Part 2

5

Class is about to end, what should happen here?

Activity #3: Lab Symbols Scavenger HuntAround the room, special symbols used to indicate extra caution

will be posted around the room. The teacher will point out lab safety equipment in the laboratory. Use the space provided for this activity to list the location of all safety equipment in your lab and what the symbol means. Also answer the questions at each station.

DISPOSAL SAFETYLocation: ____________________________________________________________Description: ________________________________________________________________________________________________________________________________________

OPEN FLAME SAFETYLocation: ___________________________________________________________Description: _________________________________________________________

______________________________________________________________________________THERMAL SAFETY

Location: ___________________________________________________________Description: _______________________________________________________________________________-

________________________________________________________FUME SAFETY

Location: ___________________________________________________________Description: _______________________________________________________________________________________________________________________________________ELECTRICAL SAFETY

Location: ___________________________________________________________Description: _________________________________________________________

______________________________________________________________________________HEATING SAFETY


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______________________________________________________________________________CLOTHING PROTECTION SAFETY


______________________________________________________________________________

EXPLOSION SAFETYLocation: ___________________________________________________________Description: _________________________________________________________

______________________________________________________________________________

EYE SAFETYLocation: ___________________________________________________________Description: _________________________________________________________

______________________________________________________________________________

POISON SAFTETYLocation: ___________________________________________________________Description: _________________________________________________________

______________________________________________________________________________

CHEMICAL SAFETYLocation: ___________________________________________________________Description: _________________________________________________________

______________________________________________________________________________

HAND WASHING SAFETYLocation: ___________________________________________________________Description: _________________________________________________________

______________________________________________________________________________Activity #4: Analyze and Conclude: Answer the questions using the list of safety rules and picture.

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1. List 3 unsafe activities shown in the picture and explain why each is unsafe.

a. Activity: Why unsafe: b. Activity: Why unsafe: c. Activity: Why unsafe:

2. List 3 safe activities shown in the picture and explain why each is safe.

a. Activity: Why safe:

b. Activity: Why safe:

c. Activity: Why safe:

Activity #5: Critical Thinking and Applications: In each of the following situations, write yes if the proper safety procedures are being followed and no if they are not. Then give a reason for your answer.

1. Gina is thirsty. She rinses a beaker with water, refills it with water, and takes a drink.

2. Bram notices that the electrical cord on his microscope is frayed near the plug. He takes the microscope to his teacher and asks for permission to use another one.

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3. The printed directions in the lab book tell a student to pour a small amount of hydrochloric acid in to a beaker. Jamal puts on safety goggles before pouring the acid into the beaker.

4. It is rather warm in the laboratory during a late spring day. Anna slips off her shoes and walks barefoot to the sink to clean her glassware.

5. While washing glassware, Mike splashes some water on Evan. To get even, Evan splashes him back.

6. During an experiment, Lindsey decides to mix two chemicals that the lab procure does not say to mix, because she is curious about what will happen.

Activity #6, Part A: Lab Equipment: Identify each of the pieces of laboratory equipment. Write the name of the lab equipment in the space by its picture, as well as the letter next to the name on this worksheet.

_________ 1._________ 2._________ 3._________ 4._________ 5._________ 6._________ 7._________ 8._________ 9._________ 10._________ 11._________ 12._________ 13._________ 14._________ 15.

BeakerGraduated CylinderTest Tube RackTest TubeWatch GlassTongsErlenmeyer FlaskScoopula/SpatulaFunnelTest Tube HolderWire GauzeRing standBunsen Lab BurnerIron RingWater Bottle

9

_________ 16._________ 17._________ 18._________ 19._________ 20._________ 21._________ 22.

Evaporating DishGogglesPipettesEye DropperHot PlateThermometer Utility Clamp

10

Activity #6, Part B: Identify which piece of lab equipment would be most useful for each of the following tasks. Some lab equipment will not be used.

1. Measuring exactly 43 mL of water ___________________________ 2. Removing solid chemicals from a reagent bottle _____________________ 3. Pouring 50 mL of liquid from one container to another ___________________________ 4. Holding 50 mL of boiling water ___________________________ 5. Dropping small quantities of liquids into test tubes ___________________________ 6. Holding a test tube over a Bunsen burner for heating ___________________________ 7. Protects your eyes from spattering solids and splashing liquids ___________________________ 8. Determine if water is boiling ___________________________ 9. Covering a beaker of boiling water to prevent splattering ___________________________ 10. These five pieces of lab equipment would hold a test tube in a beaker of boiling water above a Bunsen burner ___________________________ ___________________________ ___________________________ ___________________________ ___________________________ 11. Rinsing out glassware with distilled water ___________________________12. Heating a dissolved substance in water to drive off water ___________________________ 13. Holding hot objects in flame ___________________________ 14. Heating substances to a constant temperature ___________________________ 15. Transferring small quantities of liquid solutions from one container into another_______________________ 16. Measuring approximate amounts of liquids ___________________________

Group Work Reflection:Roles: (3 pts)

1. Task Manager: __________________________________________________2. Spokesperson: _________________________________________________3. Record Keeper: _________________________________________________4. Resource Manager _____________________________________________

Checklist: Did each person play a part in the lab and on task?

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Did you follow safety rules? Were all parts of lab completed? Was group workspace cleaned up?

Answer the following questions: (3 pts)What worked well the most during the assignment for the group?

What did not work so well during the assignment for the group? Where did you disagree as a group or saw mistakes in each other’s work?

What will you do next time to improve how your group worked together?

How much did you as an individual participate in the group? What can you do next time to improve your own performance in the lab group?

Group Rubric:

Poor1 point

Developing2 points

Good3 points

Excellent4 points

Group Rating

TeacherRating

ContributionOne or more members do

not contribute.

All members contribute, but some contribute more than

others.

All members contribute equally.

All members contribute

equally, and some even

contribute more than was required.

CooperationTeacher

intervention needed often to help group

cooperate.

Members work well together

some of the time. Some

teacher intervention

needed.

Members work well together most of the

time.

All members work well

together all of the time; assist

others when needed.

On taskTeam needs

frequent teacher

reminders to get on task.

Team is on task some of

the time. Needs

teacher reminders.

Team is on task most of the

time. Does not need any teacher

reminders.

Team is on task all of the time.Does not need

any teacher reminders.

13

Communication

Members need frequent

teacher intervention to listen to each other

and speak to each other

appropriately.

Members need some

teacher intervention to be able to listen to each

other and speak to each

other appropriately.

All members listen to each

other and speak to each other in equal

amounts.

Each member listens well to

other members. Each member

speaks in friendly and encouraging

tones.

Total Score: /32 /16 /16

TOTAL SCORE ON GROUP RATING: ___________/32 TOTAL SCORE ON REFLECTION: ______________/18 TOTAL SCORE ON COMPLETING ASSIGNMENT: _________/50

Overall Score on Lab: _____________

Date of Lab: ____________________________________

Question: Which candies are pure dyes and which skittles are mixed dyes?

Introduction: Colorful candies like Skittles are made with FD&C dyes, sugar and other substances. Chromatography is a technique used to separate different parts of a solution. It is used to identify chemicals, used to identify crime scene samples like blood or drugs and used to demonstrate the different dyes in your favorite candy.

In this experiment you will separate food dye colors into their component colors to see which dyes are pure color and which are a mixture of colors. This process of separation is called paper chromatography. Astrobiologists use chromatography to search for chemical signs of life such as chlorophyll. In this experiment, you will dissolve the colored candy shell on M&M’s, Skittles or Gobstoppers to compare the dyes in different candy shells to see if they are the same or different. Water will travel through paper by a process called capillary action. As the water travels, it picks up particles and carries them through the paper.

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Lab 2: Chromatography

Chromatography works because different parts of a solution, like the water-dye solution you drop on the filter paper, will move differently and at different rates. Some will “stick” to the paper fibers and not spend a lot of time traveling with the water, while others will travel in the water for greater distances. Different dyes will move varying distances.Filter paper works well in this experiment, because it allows water to flow through it easily. Work in groups to make concentrated solutions of Skittles coatings, and then make your own chromatograms. It’s OK to eat the Skittles after they wash off the coatings.

Pre-Lab Quick Write: What are other situations do you think we will use chromatography?

____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________VARIABLES

Independent variable:

Dependent variable:

Constants:

HYPOTHESIS*write it as if-then-because statement

EQUATIONS

It is possible to describe the position of spots (so the substances that have separated) in terms of their retention factor, the Rf value. The retention factor is define as:

Because the retention factor for a particular mixture varies depending on conditions, a sample of known composition is typically analyzed at the same time on the same sheet of paper. The Rf value is a characteristic property of a given compound in a given solvent on a particular stationary phase.

15

MATERIALS

Special Preparation - 1% salt solution (dissolve 1/8 teaspoon of salt in 3 cups of water)

Skittles – 2 of every color Scissors Pencils 1-ounce portion cups (little cups) 4-ounce portion cups (medium cups) 3 toothpicks plastic droppers beaker coffee filter paper towels water tape ruler

PROCEDURE

1. First make the candy solutions with your partner. Put 2 Skittles/M&Ms of the same color in each little cup. Add just 4 drops of plain water to the cup, NOT 4 SQUIRTS! Please don’t stir with the dropper because that will get colors on the dropper. Swirl the little cup around to dissolve the colored coating in the water. Stop swirling when the white part of the candy shows. Take out the candy and eat it or throw it away. Wipe off your fingers before you make another colored solution. Repeat steps for each color Skittles.

2. When your colored solutions are made, break 3 toothpicks in half, and put one broken end in each cup.

3. Now we’ll cut and mark some coffee filter paper to make your chromatograms. Each partner should do this job. Cut

16

3 edges off the paper circle to make it kind of square (except for the curved top). Use a pencil to mark a line about 1⁄2 inch up from the bottom edge. That’s about the width of your little finger. Make 5 pencil dots evenly spaced on the line, and mark them with letters for the 5 colors of Skittles. The dots and letters can be in any order. Curved side is at the top of the sketch.

4. Now we’ll put really tiny dots of color on each pencil dot. Use the broken end of a toothpick to put a tiny dot of color in each place. Wave the paper around to dry the spots, and add one more dot of each color right on top of the first one. Again dry the spots. Repeat two more times.

5. Fold the top of the paper over the pencil then tape it to form a loop so it can stand up in a 4 ounce cup. Stand the paper up in the cup and use a plastic dropper to add just enough salt solution to wet the bottom edge of the paper. The color dots should NOT be down in the water.

6. Now watch and see what happens. After a few minutes the water will have soaked up the coffee filter paper. When the water stops traveling up the paper, remove the coffee filter from the cup. Immediately mark where the solvent stopped traveling. Note the position of the most intense part of the separated colors and carefully circle it with pencil. Set on a paper towel to dry. Try to pick out which dyes are pure and which are mixtures.

7. Measure the distance from the straight line on which you applied the dots to the solvent front in cm. Then measure the distance from the pencil line to the center of each colored spot and calculate the Rf value from the two numbers you obtained. Repeat the procedure for each colored candy spot you applied.

OBSERVATIONS

Colors Present in Different Candies

Original Color Candy Colors present after separation

17

OBSERVATIONSDraw out and color how your chromatography paper looks below

CALCULATIONSUsing this formula below, calculate the Rf value for each color. Show all work

Original Color Candy Rf value

DISCUSSION QUESTIONS

Which candy is made up of the most substances? How do you know?

Why were you asked to use pencil in this experiment instead of pen to write?

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What is the purpose of using salt water instead of pure water?

Why is it important to use a small amount of water when making the color solution?

Explain in your own words why samples can be separated into their components by chromatography.

Why must the spot applied to a chromatography paper be above the level of the developing solvent (in this case the salt water)?

What might happen if you applied too much sample for the dots?

If two components have the same Rf value in a chromatogram. Are they necessarily identical in structure? Explain your reasoning.

CONCLUSION

My hypothesis was correct incorrect inconclusive (circle one)

2 pieces of evidence (use numbers) that proved my hypothesis to be correct:1.

2.

Sources of error:1.

2.

19

Things to change in the experiment: (THINK: If we wanted to see better separation of the mixtures in the inks, what is one thing we could change about the experiment and how could that change produce different results?)

1.

2.

Two questions about experiment:1.

2.



Checklist: Did each person play a part in the lab and on task? Did you follow safety rules? Were all parts of lab completed? Was group workspace cleaned up?





20

Group Rubric:

Poor1 point

Developing2 points

Good3 points

Excellent4 points

Group Rating

TeacherRating


not contribute.


others.





CooperationTeacher


cooperate.




needed.


time.



others when needed.

On taskTeam needs

frequent teacher



the time. Needs

teacher reminders.



reminders.



Communication




appropriately.

Members need some






amounts.




tones.


TOTAL SCORE ON GROUP RATING: ___________/32 TOTAL SCORE ON REFLECTION: ______________/18 TOTAL SCORE ON COMPLETING ASSIGNMENT: _________/50 Overall Score on Lab: _____________

21

This is GUIDED LAB—you will be designing this experiment yourself.

Date of Lab: ____________________________________

Question: What are identities of the unknown metals?

Introduction: Density is a fundamental property of matter. Density is defined as mass divided by unit volume, usually expressed in grams per cubic centimeter, or kilograms per cubic meter. The Greek letter rho (!) is the symbol for density.

The density of a pure metal is determined by a number of factors. The size of the atom, the length of the bond between atoms, and the way atoms are arranged in the crystal lattice all play a role. Metallurgy, a subspecialty of material science, is the study of metals; crystallography is the study of crystals.

This activity gives you an opportunity to practice determining the density of samples of relatively pure metals. Your task is to identify the metal in each sample cube by determining the density of each cube, and comparing results with known values. Then calculate percent error of your results.

Possible Cubes:Metal Density (g/cm3) Metal Density (g/cm3)Lead 11.3 Iron 7.9

Copper 8.9 Zinc 7.1Brass 8.6 Aluminum 2.7

Pre-Lab Quick Write: How might determining the density of the samples allow you to identify the metals?

_______________________________________________________________________________________________________________________________________________________________________________________________________________________________________VARIABLES


Dependent variable:

Constants:

HYPOTHESIS

22

Lab 3: Density of Unknown Metals

*write it as if-then-because statement

EQUATIONS

MATERIALS

One Density Cube metal labeled One ruler marked with centimeters and millimeters per team of students Balance(s) accurate to the nearest gram or better

PROCEDURE______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

23

_____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________DATA TABLE AND CALCULATIONS

Identity of Unknown Metal: _______________________________________

Show calculations on how you arrived at answer. Be sure to show precision/accuracy by calculating with significant figures and using uncertainty notation +/- :

Measurements should look like this: Example: Mass of Metal: 35.25 .01 g

Percent Error Calculations:

24

DISCUSSION QUESTIONSWhich measurement in your data table is the least precise? Justify your answer by calculating the % error implied by “ .01” in each measurement.

Example:

Mass of Metal: 35.25 .01 g

Percent Error Calculation: (0.01/35.25) x 100 = 0.028 %

Quantity of Measurement % Error Calculationmass of metal

length of metal

width of metal

height of metal

Answer to question:_______________________________________________________________________________________________________________________________________________________________________________________________________________________________________

How accurate was your calculated density compared to the measured density?

CONCLUSION



2.

25

Sources of error:1.

2.


1.

2.


2.






26



Group Rubric:

Poor1 point

Developing2 points

Good3 points

Excellent4 points

Group Rating

TeacherRating


not contribute.


others.





CooperationTeacher


cooperate.




needed.


time.



others when needed.

On taskTeam needs

frequent teacher



the time. Needs

teacher reminders.



reminders.



Communication




appropriately.

Members need some






amounts.




tones.


27

TOTAL SCORE ON GROUP RATING: ___________/32 TOTAL SCORE ON REFLECTION: ______________/18 TOTAL SCORE ON COMPLETING ASSIGNMENT: _________/50

Overall Score on Lab: _____________

Date of Lab: ____________________________________

Question: What is the average atomic mass of M&M-ium?

Introduction: What an exciting time..... yes, it is exciting! We have just discovered an unknown element and have named it m&m-ium. One of the next steps in the process is to determine the isotopic composition of our newly discovered element. In order to do this we need to determine the relative abundance of the different isotopes and use that information to calculate the average atomic mass of the element. Please follow the instructions below and use the isotopic composition to calculate the average atomic mass of the element.

Pre-Lab Quick Write: What is the difference between percent abundance and relative abundance?

____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

VARIABLES


Dependent variable:

Constants:


28

Lab 4: Isotopic Mass of M&Ms

EQUATIONS

MATERIALS

Electronic Balance Pack of M & Ms

Procedure

1. Weigh all the candies in 3 separate groups by type.

2. Count all of the candies of each different kind as well as the total of all candies.

3. Divide the mass of each isotope group (each candy type) by the number of each isotope to get the average mass of each isotope. Remember to account for significant figures!

4. Divide the number of each isotope by the total number of all “atoms” to get the relative abundance of each isotope. Report to 3 decimal places!

5. Multiply the relative abundance from Step 4 by the average mass of each isotope from Step 3 to get the relative mass of each isotope.

6. Add the relative masses to get the average mass (“atomic mass”) of the M&Mium element. This final calculation should be recorded in the Total column to 2 decimal places.

DATA TABLE AND CALCULATIONS

A. B. C. TotalMass of each isotope group

29

Number of each isotope

Average mass of one isotope

Relative abundance of each isotope group

1.000

Relative mass of each isotope

Show calculations below:


1. Your average atomic mass is closest to the average mass of which type of M&M?

Type A OR Type B OR Type C

How does this relate to its relative abundance?

2. These M&M’s are like isotopes.

a. What makes the 3 types of M&M’s similar to one another?

b. How are they different from one another?

30

AVERAGE ATOMIC MASS OF M&Mium

5. In this experiment, the mass of each M&M is like the “mass number” while the average mass of all of your M&M’s is like your “average atomic mass.” Explain why.

6. a. Find the average atomic mass obtained by another lab group in this class. _____________________

b. Why is it different from your average atomic mass?

c. How should scientists decide on one particular number for atomic mass if it is possible to have many values?

CONCLUSION



2.

Sources of error:1.

2.


1.

2.

31


2.








Group Rubric:

Poor1 point

Developing2 points

Good3 points

Excellent4 points

Group Rating

TeacherRating

One or more All members All members All members

32

Contribution members do not

contribute.

contribute, but some contribute more than

others.

contribute equally.

contribute equally, and some even


CooperationTeacher


cooperate.




needed.


time.



others when needed.

On taskTeam needs

frequent teacher



the time. Needs

teacher reminders.



reminders.



Communication




appropriately.

Members need some






amounts.




tones.


TOTAL SCORE ON GROUP RATING: ___________/32 TOTAL SCORE ON REFLECTION: ______________/18 T

OTAL

SCORE ON COMPLETING ASSIGNMENT: _________/50 Overall Score on Lab: _____________

Date of Lab: ___________________________________

33

Lab 5: 3D Models of Molecules

Introduction: Lewis structures can be used to predict molecular and ionic geometries, as well as polarity. Generally, atoms have eight electrons in their outer shell and are known as the octet rule. In addition, valence electrons around atoms (bonding pairs) or present in electron domains (lone pairs) can be used to predict the overall geometry of a molecule because electrons repel each other. This method is termed valence-shell electron-pair repulsion (VSEPR) theory. Each electron pair occupies as much space around the nucleus and inner electron shells of the atom as it can, and excludes other electrons from occupying the same space, a consequence of the Pauli Exclusion Principle.

In addition to VSEPR theory, orbital hybridization can be used to predict overall geometry (includes atoms and electron domains) as well as molecular geometry. As discussed in many chemistry books, blending of s, p, d, and f orbitals occurs based on electron wave functions first defined by Irwin Schrödinger. Hybridization occurs when low energy electrons are promoted to higher energy levels, resulting in a blended orbital of the participating orbitals (i.e., sp, sp2, sp3, sp3d, sp3d2). In this lab, you will construct molecules from Lewis structures, and correlate molecular shapes with orbital hybridizations.

Pre-Lab Quick Write: How can we use molecular models to predict shape and polarity?

_______________________________________________________________________________________________________________________________________________________________________________________________________________________________________MATERIALS

Molecular Model Kit

PROCEDUREFill in the correct element name with the appropriate color:

Black = __________ Yellow = __________ Blue = __________ Red = __________

Green = __________ Purple = __________ Orange = __________

34

You and your partner will make models of the following molecules. Use the short stick for single bonds and the bendy ones to make double bonds.

Covalent

Compound

Name of Compoun

d

Total of v.e.

Lewis structure Make a model and draw it below:

Other information Choose for each

H2O

Predicted molecular geometry:

Predicted angle:

Orbital hybridization:

Circle for each bullet: ( Polar/Nonpolar )

compound

(Polar/Nonpolar) Bond

(Resonance/no resonance)

CO2


Predicted angle:



compound



CH4


Predicted angle:



compound



HCl


Predicted angle:


compound


Orbital hybridization: (Resonance/no

resonance)

CF4


Predicted angle:



compound



NH3


Predicted angle:



compound



SO3


Predicted angle:



compound



PO43-

(3- means add an extra 3 electrons)


Predicted angle:



compound


(Resonance/no

36

resonance)

C2H2


Predicted angle:



compound



37


1. Why does the black sphere have four holes?

2. Which element(s) do you notice tend to have double bonds? Why?

3. Which element(s) do you notice tend to have triple bonds? Why?

4. Which molecules were non-polar because all bonds were non-polar?

5. Which molecules had polar covalent bonds but were non-polar because of symmetry?

6. Which two shapes appeared to produce polar molecules?

7. Name two types of substances that do not contain molecules with covalent bonds








Group Rubric:

Poor1 point

Developing2 points

Good3 points

Excellent4 points

Group Rating

TeacherRating


not contribute.


others.





CooperationTeacher


cooperate.




needed.


time.



others when needed.

On taskTeam needs

frequent teacher

reminders to


the time. Needs


time. Does not need any


any teacher

39

get on task. teacher reminders.

teacher reminders.

reminders.

Communication




appropriately.

Members need some






amounts.




tones.


TOTAL SCORE ON GROUP RATING: ___________/32 TOTAL SCORE ON REFLECTION: ______________/18

TOTAL SCORE ON COMPLETING ASSIGNMENT: _________/50 Overall Score on Lab: _____________

This is GUIDED LAB—you will be designing this experiment yourself.

Date of Lab: ____________________________________

Question: What effects do intermolecular forces in different liquids have on surface tension?

Introduction: Molecules attract one another, especially in water. The molecules underneath and on the side, thus forming a strong “skin”, attract the molecules from the top surface. This is called surface tension. Different trials may have different results because of drop size. The attraction will depend on the type of substance.

Pre-Lab Quick Write: What effects do you think intermolecular forces have on surface tension?

__________________________________________________________________________________________40

Lab 6: Penny Surface Tension & Intermolecular Forces

__________________________________________________________________________________________________________________________________________________________________________________________________________________________VARIABLES


Dependent variable:

Constants:


EQUATIONS

N/A

MATERIALS

Pennies Water Rubbing Alcohol Vinegar Oil Droppers

PROCEDURE

You will be creating a procedure using the materials provided to test different liquids for their intermolecular strength. Make sure your procedure includes at least three different trials and you calculate the average of the trials

_______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

41

____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________


Create a data table for your results


Did the penny hold the same number of drops of water during each trial? If not, why?

Which liquid had the most drops on the penny? Why do you think so?

42

Which liquid had the least number of drops on the penny? Why do you think so?

How does the surface tension affect the number of drops that can fit on a penny?

What intermolecular forces are present in water? In alcohol? In oil? In Vinegar?

Which liquid has STRONGER intermolecular forces? Explain using your data

Why do you think that liquid was able to have stay on top of the penny better? Justify your answer in terms of intermolecular forces.

CONCLUSION



2.

Sources of error:1.

2.


1.

43

2.


2.








Group Rubric:

44

Poor1 point

Developing2 points

Good3 points

Excellent4 points

Group Rating

TeacherRating


not contribute.


others.





CooperationTeacher


cooperate.




needed.


time.



others when needed.

On taskTeam needs

frequent teacher



the time. Needs

teacher reminders.



reminders.



Communication




appropriately.

Members need some






amounts.




tones.


TOTAL SCORE ON GROUP RATING: ___________/32 TOTAL SCORE ON REFLECTION: ______________/18 TOTAL SCORE ON COMPLETING ASSIGNMENT: _________/50 O

verall

Score on Lab: _____________

45

Lab 7: Ionic vs. Covalent Bonds

Date of Lab: ____________________________________

Question: How do we distinguish between ionic and covalent bonds in terms of components, hardness, melting points and electronegativities?

Introduction: Elements are not usually found alone in nature. Rather, a chemical bond may form between two or more elements to make a compound. Compounds can be characterized as ionic, covalent or metallic. In this activity, you will explore the characteristics of 2 major types of bonds: ionic bonds and covalent bonds.

PROCEDUREVisit each station and perform the following.

1. Read the “test information” provided for each station below and perform the procedure as indicated.

2. Make careful observations for the covalent substances and ionic substances.3. Write a claim as well as the evidence used to support that claim which explains how ionic

and covalent compounds are similar or different. 4. Create a question using the question wheel (each section, you should create a different

type of question). DO NOT USE KNOWLEDGE OR COMPREHENSION QUESTIONS.

Definition of claim and evidence Example sentence starters

Claim: A statement of what is true or believed to be true

It was determined that _________________

Evidence: Facts obtained from an experiment that relate to and support the claim

The evidence that supports this claim is____________

Station #1: Component of compounds: Metals or Non-metalsTest information ProcedureTo determine the type of bond in a substance, analyze whether a

nonmetal is bonded to a nonmetal

ora metal is bonded to a

nonmetal.

1. Study the chart of ionic and covalent compounds.2. Record similarities of the ionic and covalent in terms of whether they contain only metals, only non-metals, or both metals and non-metals.

Observations: Claim EvidenceIonic Covalent It was determined

that…The evidence that supports this claim is…I see/I notice

that…I see/I notice that…

46

Question about Station #1:

Station #2: Brittleness/HardnessTest information ProcedureCertain bonds tend to form brittle structures. A substance is brittle, if it is hard and fractures into many pieces when it does break.

You will be touching salt (ionic compound) and corn starch (covalent compound)Touch the substances with your fingers to determine whether they are hard or soft.

Observations Claim EvidenceIonic Covalent It was determined

that…The evidence that supports this claim is…I see/I notice

that…I see/I notice that…


Station #3: Melting pointsTest information ProcedureMelting point is the temperature at which a solid becomes liquid. Certain types of compounds tend to have higher melting points than others.

1. Look at the chart of ionic and covalent compounds.2. Compare the melting points of ionic and covalent compounds in terms of which tend to be higher and which are lower.


that…The evidence that supports this claim is…

Compound

Melting Points Compou

nd

Melting Points

CaI2 HNO3CaCl2 O3MgO P4O6KBr SO2NaCl H2O

47

I see/I notice that…


Station #4: Differences in Electronegativity ValuesTest information ProcedureCompounds may be characterized by analyzing the electronegativity differences between the elements making up the compound. Subtract the two electronegativity values from each other. (Ignore subscripts when you subtract)For example: CaCl2Ca: 1.0 Cl: 3.2The difference is 3.2-1.0 = 2.2

1. Study the chart of electronegativity values at station #8 page (or in your Glencoe textbook page 169)2. Determine the differences in electronegativity for the ionic compounds (by subtracting) and write the differences under ionic.3. Then, determine the differences in electronegativity for the covalent compounds (by subtracting) and write the differences under covalent.


that…The evidence that supports this claim is…

Compound

Difference

Compound

Difference

NaCl NO2MgBr2 BrClNaF SO2CaF2 PO4Cs2O CO2

I see/I notice that…


48








Group Rubric:

Poor Developing Good

49

1 point 2 points 3 pointsExcellent4 points

Group Rating

TeacherRating


not contribute.


others.





CooperationTeacher


cooperate.




needed.


time.



others when needed.

On taskTeam needs

frequent teacher



the time. Needs

teacher reminders.



reminders.



Communication




appropriately.

Members need some






amounts.




tones.


TOTAL SCORE ON GROUP RATING: ___________/32 TOTAL SCORE ON REFLECTION: ______________/18

TOTAL SCORE ON COMPLETING ASSIGNMENT: _________/50 Overall Score on Lab: _____________

50

Lab 8: Construction of Isomers

Date of Lab: ____________________________________

Question: How can two different molecules have the same structural formula?

Introduction: Carbon compounds often have complicatedstructures. Molecular models are usedto study them. Even simple compounds,such as butane (C4H10), have a fewstructural surprises that can be seenby using molecular models. The diagramof the molecular models to the rightshows that there is more than one wayto arrange the four carbons and tenhydrogens in butane. Molecules with thesame simple formulas but differentstructures, such as the two forms ofbutane shown to the right, are calledisomers. In this laboratoryinvestigation, you will constructmodels of all the isomers of a carboncompound. Then you will draw a pictureof each model and write the corresponding structural formula.

Pre-Lab Quick Write: How can two different molecules have the same structural formula?

_______________________________________________________________________________________________________________________________________________________________________________________________________________________________________

MATERIALS

Molecular Model Kit

PROCEDUREFill in the correct element name with the appropriate color:

Black = __________ Yellow = __________ Blue = __________ Red = __________

Green = __________ Purple = __________ Orange = __________

51

General Directions:

1. Construct a model of each molecule given. Use long sticks to represent bonds between carbons, and short sticks to represent other bonds. Attach the spheres together in such a way that all the holes are filled.

2. Based on the model, draw a molecular diagram of the compound. Draw a circle for each atom labeled with its symbol and a line for each bond. For bonds going behind the plane of the paper draw a dotted line. For bonds in the plane of the paper draw a single line. For bonds coming out of the plane of the paper, draw a heavy line in perspective.

3. Below the diagram of the molecular model draw the structural formula for the compound. 4. Move carbons and chlorine atoms to produce different structures with the same formula.

Repeat steps 2-5 of the procedure as often as necessary to find all the DIFFERENT arrangements for the molecule. Keep in mind that turning the model so its orientation is different does NOT produce a different arrangement.

Molecule #1: C5H11Cl (8 isomers)

Molecule #2: C2H2Cl2 (3 isomers)

Molecule #3: C4H9Br (4 isomers)

Molecule #4: C3H6Cl2 (4 isomers)


For each of the following pairs of molecules, state whether they are isomers, identical, or neither. Briefly explain your reasoning in each case on the next page

53

Answers: a. It is ___________________ because ________________________________________________________________________________________________________________________________________________________________________

b. It is ___________________ because ________________________________________________________________________________________________________________________________________________________________________

54

c. It is ___________________ because ________________________________________________________________________________________________________________________________________________________________________

d. It is ___________________ because ________________________________________________________________________________________________________________________________________________________________________

e. It is ___________________ because ________________________________________________________________________________________________________________________________________________________________________

f. It is ___________________ because ________________________________________________________________________________________________________________________________________________________________________






55



Group Rubric:

Poor1 point

Developing2 points

Good3 points

Excellent4 points

Group Rating

TeacherRating


not contribute.


others.





CooperationTeacher


cooperate.




needed.


time.



others when needed.

On taskTeam needs

frequent teacher



the time. Needs

teacher reminders.



reminders.



Communication




appropriately.

Members need some






amounts.




tones.


56


verall

Score on Lab: _____________

This is GUIDED LAB—you will be designing part of this experiment yourself.

Date of Lab: ____________________________________

Question: How much sweetness is in your gum?

Introduction: Have you ever wondered how much sugar is in your gum? About 50% of Americans chew gum, averaging 170 servings per person per year. Gum originated from the ancient Greeks who chew mastic, a material that originated from the bark of a tree. With the growing epidemic of diabetes, it would be useful for you to know how much sugar you are taking in one stick of gum. Percent composition (the mass by percent of the components of a substance) will help us examine the components of gum.

Pre-Lab Quick Write: How do you think we can use percent composition to figure out how much sugar is in gum?

____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________VARIABLES


Dependent variable:

Constants:


57

Lab 9: % Composition of Gum in Sugar

EQUATIONS

Percentage sugar & flavorings = Average mass sugar & flavorings x 100% Average mass of gum before chewing

MATERIALS One piece of gum with a wrapper Weigh scale

PROCEDURE

NOTE: Each person in the group should conduct the lab and take the average of people’s results in your group to calculate the percentage of sugar.

1. Obtain one piece of bubble gum of the same brand and flavor for each member of your lab group. Do not unwrap the gum. Record the brand name and flavor on your data sheet.

2. While it is still wrapped, measure the total mass of all pieces of gum in your lab group. Record this on your data sheet.

3. Without touching the gum, remove the wrapper and place the gum in your mouth and chew it. Save your wrapper.

4. While you are chewing the gum, measure the total mass of all gum wrappers in your group.

5. Calculate the average mass of one piece of wrapped gum and record this on your data sheet.

6. Calculate the average mass of one gum wrapper. Record this on your data sheet. 7. Calculate the average mass of one piece of bubble gum and record this on your

data sheet. 8. After 10-15 minutes of chewing (you should not taste sugar any more), remove the

gum from your mouth with as little moisture as possible and without touching it place it back in its own gum wrapper.

9. Measure the total mass of the gum and wrappers for your group. 10. Calculate the percentage of sugar and flavorings in the gum using the

following formula


Before chewing

58

a. Brand name of gum _____________________________b. Flavor of gum _________________________________c. Number of members in your group ____________________d. Total mass of wrapped bubble gum in group ______________g e. Total mass of gum wrappers in group __________________g f. Average mass of gum in wrapper (d / c) ________________gg. Average mass of wrapper (e / c) ____________________gh. Average mass of one piece of gum (f – g) _______________g

After chewing

i. Total mass of chewed gums and wrappers _______________gj. Average mass of one piece of chewed gum [(i-e)/c] _________gk. Average mass of sugar and flavorings in one piece of gum (h-j) _________________gl. Percentage of sugar and flavorings in gum (k/h) x 100 ______________________%

Calculations of Percent Composition

Calculations of Percent Error: (Expected yield = 2g of sugar; actual yield = what YOU calculated). USE PERCENT ERROR FORMULA)


1. How might the results be different if every student in a group chewed a different type of gum?

2. Compare your groups % composition sugar to the class mean and median. Should they be close in value? Explain. (If your data was not close to the rest of the class, explain what may have occurred.)

Group # Percent Composition of Sugar12

59

345

Class Mean:

Class Median:

3. In this experiment is the mean or median better to use for reporting your class data?

4. EXTENSIONS: Determine how many packets of sugar are in one piece of gum. First describe the lab procedure necessary, have it approved by your teacher, and carry it out.

PROCEDURE_______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

60


CONCLUSION



2.

Sources of error:1.

2.


1.

2.


2.

61








Group Rubric:

Poor1 point

Developing2 points

Good3 points

Excellent4 points

Group Rating

TeacherRating


not contribute.


others.





CooperationTeacher

intervention Members work well



62

needed often to help group

cooperate.

together some of the time. Some


needed.

most of the time.


others when needed.

On taskTeam needs

frequent teacher



the time. Needs

teacher reminders.



reminders.



Communication




appropriately.

Members need some






amounts.




tones.



Date of Lab: ____________________________________

Introduction: Have you ever wondered what it is about throwing salt on ice that makes it melt? And just why does it melt? Where does the heat come from to melt the water? Why does it freeze again on the road at night? These questions and many more about freezing and thawing will be looked at in this lab.

To start you off though let’s talk about how energy flows in any system. When you studied the air and weather you found that things always flow from areas of higher concentration to areas of lower concentration. This automatic transfer of energy and material will always work to balance the amount of energy and material. This is a natural law. From this we can deduce that heat energy will always flow from areas of higher temperature to areas of lower temperature. Knowing this simple rule, let’s look at a very tasty application of it.

63

Lab 10: Making Ice Cream—Freezing Point Depression

MATERIALS

2 quart size Ziploc Freezer bags 1 pint of whole milk 12 ice cubes 2 teaspoons of coarse salt 1 thermometer 2 clean plastic spoons 1⁄2 teaspoon vanilla extract Paper towels 3-4 ounce cups for final product

PROCEDURE

1. Place ice cubes in one Ziploc bag and place thermometer among the cubes. Leave 30 seconds. Record temperature of ice in data table.

2. Place milk in second Ziploc bag and record temperature. Add flavoring and record temperature.

3. Add 2 teaspoons of salt in bag with ice. Seal and shake gently for 30 to 45 seconds. Record temperature of results. Record temperature and observations in the data table.

4. Empty most of air from bag with milk in it. Carefully seal this bag and place it inside the bag with the ice mixture. Seal the outer bag tightly to prevent leaks.

5. Gently shake the sealed baggies back and forth in your hands to make sure that the ice mixture coats the entire surface of the milk bag. Shake for 1 minute and then carefully open the two bags and take the temperature of the inner bag (milk) only. Seal both bags. Keep shaking back and forth for 3 to 10 minutes, recording the milk temperature every minute until a solid product forms. Record final time and temperature.

6. Carefully remove the inner bag and place on paper towels. Wipe salty water from around opening. Open baggie and squeeze solid product into two cups for final test.

7. Taste your product! 8. Be sure to dispose of the ice mixture and left over product as well as spoons and

paper towels according to your instructor’s directions. 9. Wash your hands and work area before leaving the lab.


64

DISCUSSION QUESTIONS1. What happened shortly after you added the salt to the ice cubes? Was the

temperature above or below the freezing temperature for water?

2. What is the only factor that could have caused the changes shown in question 1? What does this tell you about the freezing point temperature of salt water compared to fresh water?

3. Heat energy is needed to change phase from a solid to a liquid. List the possible sources of the heat needed for this phase change in your baggie. Which source do you think is the best possibility and why?

4. In looking at the temperature changes shown on your data table, explain how the energy flow of the baggie system resulted in your tasty treat for an end product. Where is the energy flowing from and where is it going to?

5. In the radiator of your car you put a combination of antifreeze and water to keep your car engine cool in the summer and prevent the radiator from freezing in the

65

winter. Explain how you think this works in terms of what you saw in the experiment you just did.








Group Rubric:

Poor1 point

Developing2 points

Good3 points

Excellent4 points

Group Rating

TeacherRating


All members contribute,



66

not contribute.

but some contribute more than

others.

equally. equally, and some even


CooperationTeacher


cooperate.




needed.


time.



others when needed.

On taskTeam needs

frequent teacher



the time. Needs

teacher reminders.



reminders.



Communication




appropriately.

Members need some






amounts.




tones.



verall

Score on Lab: _____________

Date of Lab: ____________________________________

67

Lab 11: Conservation of Mass

Introduction: The Law of Conservation of Mass states that mass in a closed system will remain constant (same). Matter cannot be created or destroyed. A closed system is one to which nothing can be added of taken away.

Reaction #1: Baking Soda & VinegarMATERIALS

2 beakers balance vinegar baking soda plastic bag

PROCEDURE

Part 1: Open System1. Calibrate, or set the balance to 0. 2. Fill a beaker with 20 mL of vinegar. 3. Add one spoonful of baking soda into the second beaker. 4. Place both beakers on the balance & record the starting mass. 5. Dump the baking soda into the beaker. Do not stir. 6. Place the empty beaker back on the balance. Record the ending mass, including both

beakers. 7. Calculate the amount of mass changed.

Part 2: Closed System1. Clean & dry both beakers. 2. Fill a clean beaker with 30 mL of vinegar. 3. Add one spoonful of baking soda into a clean plastic bag. 4. Gently place the beaker with vinegar in the plastic bag. Do NOT spill the vinegar! 5. Trytopushallairoutofthebag.Sealthebag&placeitonthebalancewithoutspilling the vinegar.

Record the starting mass. 6. Without opening the bag, tip the beaker, mixing the vinegar with the baking soda. 7. Still without opening the bag, record the ending mass of the contents of the plastic bag. 8. Calculate the amount of mass changed.


Baking Soda & Vinegar: Open System

Starting mass: ___________ g

Ending mass: ____________ g

68

Amount Changed: ________ g

Baking Soda & Vinegar: Closed System

Starting mass: ___________ g

Ending mass: ____________ g

Amount Changed: ________ g

DISCUSSION QUESTIONSCompare part 1, the open system, to part 2, the closed system. What was the same? What was different?

How does the conservation of mass relate to this activity?

Reaction #2: Alka Seltzer & WaterMATERIALS

1 Erlenmeyer flask balance water 2 effervescent tablets like Alka Seltzer tablets balloon

PROCEDURE

Part 1: Open System1. Confirm that the balance is still calibrated. 2. Fill a clean Erlenmeyer flask with 50 mL of water. 3. Place the flask & a tablet on the balance & record the starting mass. 4. Place the tablet into the flask of water. Swirl & wait 3 minutes. 5. Once the reaction is complete, record the ending mass. 6. Calculate the amount of mass changed.

Part 2: Closed System1. Thoroughly clean the flask & fill with 50 mL of water 2. Place an effervescent tablet into a balloon. You may need to break the tablet in

69

half. 3. Place the balloon around the rim of the flask, but do not let the tablet fall into the

water. 4. Find & record the starting mass of the flask & balloon with tablet. 5. Lift the balloon, causing the tablet to fall into the water. Swirl & wait 3 minutes. 6. Once the reaction is complete, record the ending mass. 7. Calculate the amount of mass changed.


Water & Alka Seltzer: Open System Starting mass: ___________ gEnding mass: ____________ g Amount Changed: ________ g

Water & Alka Seltzer: Closed System Starting mass: ___________ gEnding mass: ____________ g Amount Changed: ________ g

DISCUSSION QUESTIONS1. As you know, scientists write chemical reactions like mathematical formulas. The reactions

are on the left of the arrow & the products are on the right of the arrow. Reactants → Products

The effervescent tablet contains a chemical called sodium bicarbonate (baking soda!). This chemical reacts with water according to the following reaction:

H20+NaHCO3 → NaOH + CO2 +H20a.Count the number of each element, on each side of the equation, & record below. For

example, there are 3 hydrogens on the reactant side.

Element Hydrogen Carbon Oxygen SodiumReactantsProducts

b.Is this reaction “balanced”? Explain.

2. Compare part 1 of this reaction, the open system, to part 2, the closed system. What did you notice?

3. How does this reaction compare to the reaction of baking soda & vinegar?

70








Group Rubric:

Poor1 point

Developing2 points

Good3 points

Excellent4 points

Group Rating

TeacherRating


not contribute.


others.





71

CooperationTeacher


cooperate.




needed.


time.



others when needed.

On taskTeam needs

frequent teacher



the time. Needs

teacher reminders.



reminders.



Communication




appropriately.

Members need some






amounts.




tones.



verall

Score on Lab: _____________

Date of Lab: ____________________________________

Question: How do we distinguish between a single replacement and double replacement reaction?

72

Lab 12: Types of Reactions

Introduction: You have studied several types of reactions. Singe replacement reactions are reactions in which one element replaces the place of another element in a compound. Double replacement reactions on the other hand are reactions in which the positive elements and the negative elements of each compound switch places to form two new compounds. Very often, a solid or a gas forms.

MATERIALS

Zinc metal Hydrochloric Acid (HCl) Aluminum Foil NaOH

KNO3

KI KOH CuCl2

Iron Nail Copper sulfate KCl Lead (II) nitrate

PROCEDURE & OBSERVATIONSSingle Replacement Reaction #1

Place a small piece of zinc metal in a test tube containing 2 mL of 3M HCl, and record your observations. Dispose of the contents of the test tube in the waste jar in the hood.

Zinc Metal HClBefore reaction

During reaction

After reaction

(a) Write balanced chemical equation based from reaction you performed:

_____________________________________________________________________________(b) Explain in terms of activity series, why did a reaction occur?

__________________________________________________________________________________________________________________________________________________________

Single Replacement Reaction #2: Place a piece of aluminum foil in a test tube and add sodium hydroxide.

Aluminum Metal NaOHBefore reaction

During reaction

73

After reaction



__________________________________________________________________________________________________________________________________________________________

Single Replacement Reaction #3: Pour 3 ml of copper sulfate solution into a tube. Drop an iron nail into the tube. In a short time remove the nail and examine the portion that was immersed in the copper sulfate solution

Iron Metal Copper SulfateBefore reaction

During reaction

After reaction



__________________________________________________________________________________________________________________________________________________________

Decomposition Reaction

NOTE: All waste for this part of the experiment should be poured into the labeled waste containers in the hood and the test tubes rinsed with a minimum amount of water, which should also be placed into the waste container. DO NOT dispose of any solutions or solids down the drain.

1. Wash your well-plate thoroughly with soap and water, then rinse it completely with deionized water. A dirty well-plate can give incorrect results.

2. Place 5 drops of each aqueous solution in the correct wells based on the table you constructed for your observations.

74

KNO3(aq) KI(aq) KOH(aq)

CuCl2(aq)

Pb(NO3)2(aq)

KCl(aq)

Refer to your data table for the following selected sets of reactants and fill in the following blanks and beaker drawings. If there is no net ionic reaction because all the ions are spectators still complete the molecular reaction, the ionic reaction, and the beaker drawings, then put NR only for the net ionic reaction. An example NOT from this experiment is presented first.

Example: calcium acetate and ammonium sulfate Reaction type: precipitation

Molecular: Ca(CH3COO)2(aq) + (NH4)2SO4(aq) CaSO4(s) + 2 NH4CH3COO(aq)

Ionic: Ca2+(aq) + 2 CH3COO-(aq) + 2 NH4+(aq) + SO42-(aq) CaSO4(s) + 2 CH3COO-(aq) + 2 NH4+(aq)

Net Ionic: Ca2+(aq) + SO42-(aq) CaSO4(s)

1. potassium iodide and copper chloride Reaction type: _______________

Molecular:______________________________________________________________________

Ionic:_________________________________________________________________________

Net Ionic: ______________________________________________________________________

75

2. potassium iodide and lead (II) nitrate Reaction type: _______________

Molecular:______________________________________________________________________

Ionic:_________________________________________________________________________

Net Ionic: ______________________________________________________________________

3. potassium hydroxide and copper chloride Reaction type: _______________

Molecular:______________________________________________________________________

Ionic:_________________________________________________________________________

Net Ionic: ______________________________________________________________________

4. potassium hydroxide and lead (II) nitrate Reaction type: _______________

Molecular:______________________________________________________________________

76

Ionic:_________________________________________________________________________

Net Ionic: ______________________________________________________________________


1. Suppose you had an unknown solution that contained either dissolved NaCl, or NaNO3. You added AgNO3 to the unknown solution and observed that no solid forms. What can be concluded about the unknown solution? (use the solubility rules)

2. Suppose you tired to carry out a double-replacement reaction by mixing together equal volumes of a solution that contained dissolved NaF and a solution that contained dissolved NaCl. Would you expect a reaction, if so write the balanced chemical equation?

Complete the following statements about the characteristics of single and double replacement reactions:

During a single replacement reaction, a(n) (combined, uncombined)______________element replaces a (n)

(combined, uncombined) ______________ element from its compound.

The products of a single replacement reaction are always (an element and a compound,, two elements, or two compounds) ____________________________.

During a double replacement reaction, two (elements, compounds) ______________ exchange metallic and

77

nonmetallic elements to form two new (compounds, elements) ______________.








Group Rubric:

Poor1 point

Developing2 points

Good3 points

Excellent4 points

Group Rating

TeacherRating


not contribute.

All members contribute, but some contribute




78

more than others.


CooperationTeacher


cooperate.




needed.


time.



others when needed.

On taskTeam needs

frequent teacher



the time. Needs

teacher reminders.



reminders.



Communication




appropriately.

Members need some






amounts.




tones.



verall

Score on Lab: _____________

Date of Lab: ____________________________________

79

Lab 13: Heating Curve of Water

Question: How much heat is absorbed in total as water undergoes phase changes and temperature changes from ice to vapor?

Introduction: When heat is added to ice, it will melt and change to water. As water is heated, its temperature rises. Eventually, the water will boil and change into a vapor (gas). The substance has gone through two changes in phase. The temperatures at which these phase changes occur are important characteristic properties. The relationship between the heat energy and the behavior of the substance is also important in understanding the difference between heat and temperature. In this lab experiment you will be dealing with the relationship between heat energy and changes in phase of matter. In your groups you will construct a phase diagram and an explanation of what is going on. You will also calculate how much heat was absorbed as the water underwent the phase changes.

Pre-Lab Quick Write: In a cooking class a teacher told the class to bring the water to a boil and allow it to boil for five minutes so that it would be “good and hot.” What is wrong with this statement?

____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________VARIABLES


Dependent variable:

Constants:HYPOTHESIS*write it as if-then-because statement

EQUATIONS

q = mHf q = mHv q = mct

MATERIALS

1 beaker filled with ice 1 hot plate 1 thermometer

80

1 stopwatch/timer

PROCEDURE

1. Fill a 250 mL beaker with 2/3 full with ice and add 80 mL water to cover the ice. 2. Place the beaker on a hot plate.3. Stir carefully with a stirring rod until the temperature stabilizes at or below 0.0°C. 4. Turn the hot plate on the highest setting.5. Record the temperature every 30 seconds in your observation table.6. Record the time at which all the ice has melted. 7. Continue to heat the water for at least 3 minutes after the water begins to boil,

recording the temperature at 30-second intervals. 8. Record the time at which the water begins to boil.9. After three minutes, turn off the burner and record the time.10. Plot a heating curve using your data. On the curve, indicate the point at

which the ice melted and the liquid water boiled.DATA TABLE AND CALCULATIONS

Time Elapsed (minutes: seconds)

Beaker Temperature

(°C)

Time Elapsed (minutes: seconds)

Beaker Temperature

(°C)

Time Elapsed

(minutes: seconds)

Beaker Temperature

(°C)

0:00 13:00 26:000:30 13:30 26:301:00 14:00 27:001:30 14:30 27:302:00 15:00 28:002:30 15:30 28:303:00 16:00 29:003:30 16:30 29:304:00 17:00 30:004:30 17:30 30:305:00 18:00 31:005:30 18:30 31:306:00 19:00 32:006:30 19:30 32:307:00 20:00 33:007:30 20:30 33:308:00 21:00 34:008:30 21:30 34:309:00 22:00 35:00

81

9:30 22:30 35:3010:00 23:00 36:00

82

10:30 23:30 36:3011:00 24:00 37:00

83

11:30 24:30 37:3012:00 25:00 38:0012:30 25:30 38:30

Heating Start Time______________ Heating End Time_______________

Ice Melting Time________________ Water Boiling Time______________

Graph the heating curve below and label where each phase is present:

84

DATA

TABLE AND CALCULATIONS

85

Measurements

1. Mass of beaker + water (g)2. Mass of empty cup (g)3. Mass of water (g) (Step 1-Step 2)

Calculating Heat from Melting

1. Total mass of water used

2. Heat of Fusion

Answer: Energy absorbed (J)

Calculating Heat from Boiling

1. Total mass of water used

2. Heat of Vaporization

Answer: Energy absorbed (J)

Calculating Heat Gained in solid phase1. Total mass of water used

2. Change in water temperature in solid phase only

86

3. Specific heat of water

4. Energy absorbed/lost by the water (J)[see formula: Q = mcT]

Calculating Heat Gained in liquid phase1. Total mass of water used

2. Change in water temperature in liquid phase only



Calculating Heat Gained in gas phase1. Total mass of water used

2. Change in water temperature in gas phase only



Add up the heat calculated from the boxes labeled #4 to determine total amount of heat absorbed: __________________DISCUSSION QUESTIONS

What was happening to the water when the lines on the graph were mostly flat? What kind of energy was being added to the system?

What was happening to the water when the lines on the graph were mostly sloped? What kind of energy was being added to the system?

87

Was the energy flow into the beaker constant? How did you know? Can you make a useful heating curve if the energy flow is not constant? Why or why not?

Based on your heating curve, determine the melting and boiling points of water. Does this match the accepted values (0°C for melting and 100°C for boiling)? Calculate percent error.

CONCLUSION



2.

Sources of error:1.

2.


1.

88

2.


2.








Group Rubric:

89

Poor1 point

Developing2 points

Good3 points

Excellent4 points

Group Rating

TeacherRating


not contribute.


others.





CooperationTeacher


cooperate.




needed.


time.



others when needed.

On taskTeam needs

frequent teacher



the time. Needs

teacher reminders.



reminders.



Communication




appropriately.

Members need some






amounts.




tones.



verall

Score on Lab: _____________

90

Lab 14: Gas Laws

This is GUIDED LAB—you will be designing part of this experiment yourself.

Date of Lab: ____________________________________

Question: How does the change in temperature affect the amount the balloon expands?

Introduction: What will happen when an alka-seltzer tablet is dissolved in water or pop rocks candy dissolved in soda? In a glass bowl filled with water an alka-seltzer tablet is added. The tablet starts to dissolve. This creates a gas called carbon dioxide. When the carbon dioxide is being released, it creates pressure inside the film canister. The more gas that is produced the more pressure builds up until the cap is blasted down and the rocket is pushed up. In this lab, you will design an experiment using alka seltzer tablets and water or pop rocks and soda to test gas laws. You will be expected to conduct two trials and average the results of your trial for each temperature tested.

VARIABLES Independent variable:

Dependent variable:

Constants:


MATERIALS Alka-Seltzer tablets or pop

rocks candy Water or soda Thermometer

Hot plate Ice String

Ruler Balloons

PROCEDURE_____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

91

___________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________DATA TABLE

Create a triple bar graph showing the results from your data. The circumference will be the y-axis and the temperature will be the x-axis.

92

CONCLUSION



2.

Sources of error:1.

2.


1.

2.


2.




94





Group Rubric:

Poor1 point

Developing2 points

Good3 points

Excellent4 points

Group Rating

TeacherRating


not contribute.


others.





CooperationTeacher


cooperate.




needed.


time.



others when needed.

On taskTeam needs

frequent teacher



the time. Needs

teacher reminders.



reminders.



CommunicatioMembers

need frequent Members

need some All members listen to each


95

n teacher intervention to listen to each other


appropriately.





amounts.



tones.



verall

Score on Lab: _____________

Date of Lab: ____________________________________

Question: How does vapor pressure effect evaporation?

Introduction: When a liquid evaporates, the distance between its particles increases tremendously, causing a significant increase in their potential energy. The energy needed to evaporate 1 g of a liquid, known as the heat of vaporization, is much greater than the energy needed to cause a 1°C rise in the temperature of a liquid. When a liquid evaporates, it takes the energy needed for the process from its surroundings. This is why sweating cools you and you may feel chilled when you step from the shower. Some liquids cool your skin even faster than water. Did you ever notice how cold it feels when the doctor cleans your skin with alcohol prior to giving an (ouch!) injection? In this laboratory investigation, you will explore this phenomenon.

Pre-Lab Quick Write: Why do you think it feels cold when alcohol is wiped on your skin?

____________________________________________________________________________________________________________________________________________________________________________________

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Lab 15: Vapor Pressure & Evaporative Cooling

________________________________________________________________________________________________________________________________VARIABLES


Dependent variable:

Constants:


EQUATIONS

N/A

MATERIALS

Ethanol Filter paper propanone (acetone) Ring stand (3) Rubber bands (3) Thermometers (3) Thermometer clamp (3) Water

PROCEDURE

1. Set up three beakers, each containing one of the following liquids: propanone; ethanol; and water.

2. Place a piece of filter paper in the liquid in each of the beakers, and allow it to soak for several minutes.

3. Using a thermometer, measure the temperature in the room. Record the result in the data table on the next page.

4. Set up three thermometers on ringstands with thermometer clamps as shown in the diagram to the right.

97

5. Wrap the bulbs of each of the thermometers with one of the soaked pieces of filter paper. Keep track of which liquid is in contact with each thermometer.

6. Secure each piece of filter paper by wrapping it with a rubber band.

7. Watch the temperatures on each of the thermometers for several minutes. As the liquid evaporates, the temperature will begin to drop. Note which one begins to drop first, and which drops fastest.

8. Make note of the lowest temperature each thermometer reaches, and record it in the data table on the next page.

9. Calculate the absolute value of the temperature changesubtracting the coldest temperature reached by each from room temperature.

10. Determine the normal boiling point of each liquid by looking at Table H, Vapor Pressure of Four Liquids, on your reference tables. Record the boiling points in your data table on the next page.

11. On a separate sheet of graph paper, prepare a graph of boiling point versus temperature change. Use the x-axis for boiling point and the y- axis for temperature change. Plot the points and draw the best straight line or curve through the points.

OBSERVATIONS AND DATA TABLE

Room Temperature: _______________________________

Liquid Normal Boiling Point

Lowest Temperature

Reached

Temperature Change

Propanone

Ethanol

Water


98

1. Why does the temperature drop when the thermometer covered with wet filter paper is left to dry?

2. What is the relationship between the normal boiling point of a liquid and how well it cools by evaporation?

3. Predict the lowest temperature a thermometer wet with isopropyl alcohol would reach if its boiling point is 82.4°C.

4. Which of the liquids tested has the highest vapor pressure at room temperature? Which has the lowest vapor pressure? What is the relationship between the vapor pressure of a liquid and how well it cools by evaporation?

5. Which of the liquids you tested has the strongest forces holding its molecules to each other? What evidence does the laboratory investigation provide to support your answer?

CONCLUSION



99

2.

Sources of error:1.

2.


1.

2.


2.


7. Task Manager: __________________________________________________8. Spokesperson: _________________________________________________9. Record Keeper: _________________________________________________10.Resource Manager _____________________________________________



What did not work so well during the assignment for the group? Where did you disagree

100

as a group or saw mistakes in each other’s work?



Group Rubric:

Poor1 point

Developing2 points

Good3 points

Excellent4 points

Group Rating

TeacherRating


not contribute.


others.





CooperationTeacher


cooperate.




needed.


time.



others when needed.

On taskTeam needs

frequent teacher



the time. Needs

teacher reminders.



reminders.



Communication




appropriately.

Members need some






amounts.




tones.


101


Date of Lab: ____________________________________

Question: How much acid is really in your candy?

Introduction: Sour taste is the body's way of identifying acid, so if your candy tastes sour, it contains acid. The purpose of this experiment is to see how much acid candy can produce in a solution of warm water, baking soda and melted candy.

VARIABLES


Dependent variable:

Constants:


EQUATIONS

N/A

MATERIALS pH meter/strip 5 plastic spoons Knife (optional)

102

Lab 16: Acidity of Candy

A measuring cup (half of a cup for each trial.) Scale Small beakers Hot plate Water Baking soda (1 container) Sour patch kids Sour skittles Warheads Lemonheads Nerds Cups (5 1/2 inches)

PROCEDURE1. Gather all materials and equipment needed.2. Weigh the candy to 0.5 grams and get the hot water ready. 3. Put each type of candy in a different cup and put it in with the hot water until it is

dissolved.4. Add a tablespoon of baking soda with the candy and stir until it is dissolved.5. Dip the pH strip in the water and wait thirty seconds for the results to develop. Then

record all data.

DATA TABLE

Candy pH level Color changeSour patch kidsSour skittlesWarheadsLemonheadsNerds


Rank the candies following in order of increasing acidity:

How does a difference in 1 pH unit change in terms of H+ concentration? Example: How does a pH of 3 differ from pH of 4? Which one is stronger or weaker? Why?

103

Neutralization: Whenever you mix an acid with a base, they neutralize each other. If this is the case, why is Alka- Seltzer used to treat stomach aches? (Note: excess stomach acids cause stomach aches)

Acid Rain: What is acid rain and how is it a problem to oceans, rivers, lakes, ponds ect.?

CONCLUSION



2.

Sources of error:1.

2.


1.

104

2.


2.








Group Rubric:

Poor Developing Good

105

1 point 2 points 3 pointsExcellent4 points

Group Rating

TeacherRating


not contribute.


others.





CooperationTeacher


cooperate.




needed.


time.



others when needed.

On taskTeam needs

frequent teacher



the time. Needs

teacher reminders.



reminders.



Communication




appropriately.

Members need some






amounts.




tones.



verall

Score on Lab: _____________

106

Lab 17: Titration

Date of Lab: ____________________________________

Introduction: Titration is the name given to the process of determining the volume of a solution needed to react with a given mass or volume of a sample. You will use this process to study quantitatively the reaction between an acid and a base. Phenolphthalein will be used as the indicator in this experiment since its color change occurs when the same number of moles of acid and base has been added. This point in the reaction is called the equivalence point or the end point. Using a measured mass of a solid acid (such as KHC4H4O6), you will standardize a sodium hydroxide solution—that is, determine its concentration in moles per Liter. Using the standard base, you will then titrate samples of the strong acid, HCl and a vinegar solution to determine their concentrations.

EQUATIONS

MAVA = MBVB

Molarity = moles of solute Litter of solution

MATERIALSAt each station you should find:

ring stand with buret clamp two burets (labeled “acid” and “base”) two funnels 250 mL Erlenmeyer flask index card with dark line

Shared equipment on a tray: bottle of phenolphthalein (“phth”) bottle of distilled water (blue top) 50-mL beakers labeled “acid” 100-mL beakers labeled “base” vials of solid acid (cream of tartar)

PROCEDUREI. Standardization of the NaOH solution of a base with a solid acid.

1. Obtain the solid acid from your teacher. Find the mass of the vial to the nearest 0.01 g. Remove about 0.7 g into a clean flask. Find the mass of the vial and contents again. Dissolve the sample in 50 mL of distilled water, add 3 drops of phenolphthalein. If all the acid does not dissolve at this point, it will dissolve later during the titration when the acid will be converted to the more soluble sodium salt.

2. Fill the buret at your station with base (NaOH) solution using the 100-mL beaker at your station. (Read the labels carefully.)

107

3. Record the liquid level in the buret by reading the bottom of the meniscus to the nearest 0.1 mL.

4. Hold the neck of the Erlenmeyer flask with one hand and manipulate the buret with the other. As you add the sodium hydroxide, gently swirls the flask so the solutions will mix. Continue adding sodium hydroxide until the first faint pink color develops. If the color disappears upon mixing the solution, add more sodium hydroxide, drop by drop, until a persistent pink color is obtained. (Take care not to go beyond the last calibration marks on the buret.) Record the liquid level at the bottom of the meniscus of the base buret. Rinse the Erlenmeyer flask thoroughly before repeating the titration. Be careful not to overrun the endpoint. If you pass the endpoint, add a little more of the solid acid and reweigh the vial. Be sure to include the mass of any solid acid added to the mass of your sample. Re-titrate to the endpoint and record the final buret reading.

5. Repeat the titration with a similar sample. Use the knowledge you gained in the first titration. That is, assuming you used 40 mL of base to titrate a certain mass of acid, and that you have almost the same mass of acid for the second trial, you can run 35 mL of base into the flask rapidly and complete the last part of the titration cautiously.

6. Repeat your titrations until the ratio of mass of solid acid to volume of base used agrees to within 1%

II. Titration of the Strong Acid, HCl

1. Refill base buret. Check to be certain that the acid buret is also filled.

2. Record the liquid level in the acid buret to the nearest 0.1 mL. Let about 10 mL of hydrochloric acid flow into a clean 250-mL Erlenmeyer flask. Record the final volume in the buret. Add about 15 mL of distilled water and 3 drops of phenolphthalein.

3. Record the liquid level in the base buret and add base to the acid sample while swirling. Continue adding sodium hydroxide until the first faint pink color develops. If the color disappears upon mixing the solution, add more sodium hydroxide, drop by drop, until a persistent pink color is obtained. Record the liquid level at the bottom of the meniscus of the base buret. Rinse the Erlenmeyer flask thoroughly with distilled water before repeating the titration.

4. Refill the base buret and perform at least one more titration. Repeat until you obtain ratios of volume of acid to volume of base that agree to within 1 percent.

III. Titration of Vinegar

1. Refill the base buret and record the liquid level in the base buret.

2. Using the volumetric pipette, measure 10.0 mL of the diluted vinegar solution (10%) into a clean 250- mL Erlenmeyer flask. Add about 15 mL of distilled water and 3 drops of phenolphthalein.

3. Follow the directions above to titrate the vinegar sample.

108

DATA TABLE

Standardization of Base with Solid Acid

Titration of HCl

Titration of Vinegar

109

Calculations: (Show work when possible and pay attention to significant figures) 1. Task 1: Determine the concentration of NaOH used to titrate the solid acid.

a) The solid acid we use is potassium hydrogen tartrate or potassium bitartrate. This is also called cream of tartar and is used in place of lemon juice or vinegar in some recipes. It is a component of baking powder. Redraw the structural formula to the right of the jar showing all of the atoms. The abbreviated structural formula above does not show the carbon atoms (they are the intersections of lines) and does not show all of the hydrogen atoms (you are supposed to know where they are.) The formula of potassium hydrogen tartrate is: KHC4H4O6

What is the molar mass of the solid acid? _______________

b) Use the mass of your solid acid to determine the number of moles of H+ in your acid?

c) How many mole of OH are in the volume of NaOH used to titrate the acid? _________________

d) What is the concentration of the NaOH solution? ______________

110

2. Task 2: Knowing the concentration of NaOH, determine the concentration of the HCl solution.

3. Task 3: Determine the concentration of the diluted vinegar solution. Remember that the solution is 10% vinegar (by volume), calculate the concentration of the original vinegar. The vinegar is labeled as 5% acetic acid by mass (HC2H3O2), which should be 0.833 M HC2H3O2.

CONCLUSION

Sources of error:

1.

2.


1.

2.

Two questions about experiment:

1.

2.

111








Group Rubric:

Poor1 point

Developing2 points

Good3 points

Excellent4 points

Group Rating

TeacherRating


not contribute.


others.





112

CooperationTeacher


cooperate.




needed.


time.



others when needed.

On taskTeam needs

frequent teacher



the time. Needs

teacher reminders.



reminders.



Communication




appropriately.

Members need some






amounts.




tones.



Date of Lab: ____________________________________

Introduction: Electricity can be used to cause a chemical change. We will try this using our pencil electrolysis apparatus. Notice that it is two pencils taped together with a 9-volt battery. The battery top has wires that connect to the graphite of each pencil. Remember, C(graphite) is a conductor due to the extended pi bond (chicken-wire shaped) above and below the sp2 hybridized carbon atoms. The carbon has another benefit in that they are relatively inert and will not react with the solutions we will use.

113

Lab 18: Electrolysis

MATERIALS two pencils Na2SO4 Universal indicator Distilled water KI Black/red wires Square battery

PROCEDURE1. Get a clean Petri dish and put in some distilled H2O. Place the tips of your pencil

apparatus into the distilled water and make observations. ________________________________________________

2. You probably notice that nothing happens because distilled H2O is a very poor conductor of electricity. Add a pinch of Na2SO4 to your water to increase the conductivity. Also, add a few drops of universal indicator. (Don’t use the pencil apparatus to mix the solution.) You should see a green color if your water is neutral. Place the tips of your pencil apparatus into the distilled water and make observations. __________ ______________________________________________________________________________________________________________________________________________

3. At one pencil tip, H+ ions are being formed. At the other pencil tip, OH− ions are being formed. We need to explain this observation. Let’s consider the negative electrode first.Water surrounds the negative electrode and _____ (Na+ | SO4

2-) ions will be attracted to the negative electrode. The negative electrode is negative because it has ______________ (too many | too few) electrons. It will force a chemical to ________ (gain | lose) electrons which is called _____________ (oxidation | reduction).

This chart shows various reduction reactions with the most likely to be reduced higher in the chart. So, for our two choices of reductions at the negative electrode, write the chemical reaction that occurs:

114

The color at the negative electrode is __________ due to the presence of _____ ions. Since reduction is occurring at the negative electrode, this is the _________ (anode | cathode).

4. At the positive electrode, H2O is oxidized. The S in SO42- is already in the most

oxidized state it can be in, so it does not change. Use the chart to find the oxidation of H2O. Since this is a chart of reductions, you must look at the equations backwards. Find the reaction in which the H2O is oxidized.

5. In this situation, water is both oxidized and reduced. Write the two equations and add them together. You will need to double one of the reactions to cancel the e−’s. Write the net reaction.

Oxidation:

Reduction:

Net Reaction:

Remove the pencil apparatus and mix the solution. Observations: _____________________________

Explain: __________________________________________________________________

6. Rinse your Petri dish and again add distilled water. Using a spatula, add a “pinch” of KI to the water and dissolve using a clean glass-stirring rod. Add a few drops of phenolphthalein

indicator solution. Place a strip of index card down the center of the dish to separate the dish into two areas. (It doesn’t have to be at all perfect.) Now, touch the pencil apparatus to the solution, one tip on each side of the card. Hold it still and make observations. _________________________________________

________________________________________________________________

In this solution, you have K+, I−, and H2O. It is now your task to determine the two possible reactions at the anode. Write the two possible reductions that occur. Use the reduction potential chart to determine which of the two will actually occur.

115

7. It is a little more tricky to determine which oxidation will occur at the anode .In this solution, you have K+, I−, and H2O. Determine the two possible oxidations. You will consider the reactions on the chart below written in reverse. Use the reduction potential chart to determine which of the two will actually occur by changing the sign of the reduction potentials. You are now listing the oxidation potentials. The higher the E° value, the more likely the chemical is to be oxidized.

8. Link your equations with the observations.

116

9. What do you predict would happen with a solution of CuCl2? What reactions would occur? What would you observe? Rinse your Petri dish and try it.

CONCLUSION

Sources of error:

1.

2.


1.

2.


117

1.

2.








Group Rubric:

Poor1 point

Developing2 points

Good3 points Excellent

4 pointsGroup Rating

TeacherRating

118


not contribute.


others.





CooperationTeacher


cooperate.




needed.


time.



others when needed.

On taskTeam needs

frequent teacher



the time. Needs

teacher reminders.



reminders.



Communication




appropriately.

Members need some






amounts.




tones.



Date of Lab: ____________________________________

Introduction: Many elements have several forms, called isotopes. Some isotopes of

119

Lab 19: Half Life

some elements are radioactive (radioisotopes). Over time, atoms of radioisotopes decay by giving off radiation in the form of energy and nuclear particles. After emitting radiation, the original atom changes into an atom of a new element. Some of these new elements are radioactive while others are not. Though it is impossible to predict when a particular atom will decay, the length of time it takes for half of the atoms in a radioactive sample to decay (half-life) is amazingly consistent. Each different radioisotope has a constant and unique half-life. Each radioactive isotope has a characteristic half-life, ranging from less than a second to millions of years. In this activity, you will use pennies that can land “heads up” (nuclei that have undergone radioactive decay) or “tails up” (nuclei that haven’t yet decayed) as a model of half-life.

MATERIALS 100 pennies or skittles or M&Ms paper or plastic cup a box

PROCEDURE1. Take 100 pennies representing a radioactive substance, “headsium.” When the

pennies are heads up, they are radioactive (headsium). When the pennies are tails up, they are no longer radioactive (tailsium)

2. Place the 100 pennies in the cup and shake.3. Spill the pennies out of the cup onto your box4. Remove the pennies which land tails up, put them on the side of your lab table5. Count the number of pennies, which remain (heads up) and record it in your data

table.6. Place the remaining pennies in the cup and shake again7. Repeat Steps #3-5 until only one penny remains or the box is empty.8. Perform two additional trials by repeating Steps #2-7.9. Using the data you collected in this lab, construct a line graph of the number of

pennies vs. shakes for all three trials. Label your axes and title your graph(s) appropriately.

DATA TABLEUsing the data you collected in this lab, construct a line graph of the number of pennies vs. shakes for all three trials. Label your axes and title your graph(s) appropriately.

120


Show work for calculations

1. In the experiment, what was the half-life of the element pennium? How did you find it? Show the work for each trial and then take the average.

2. At the end of two half-lives, what fraction of the atoms had not decayed? Show the work for each trial and then take the average.

3. Theoretically, 50% of the pennies should ‘decay’ with each shake. Select one of your

121

three trials and determine the average percentage of pennies that were removed with each shake.


1. How does this lab demonstrate the concept of “half life”?

2. In this lab, what did the pennies represent? What did one trial represent?

3. Explain, in terms of radioisotope and half-life, why the number of tailsium atoms you removed decreased after each half-life.

4. Explain why the number of tailsium atoms left was not always exactly half of the previous step.

5. Theoretically, 50% of the pennies should ‘decay’ with each shake. Did you actually remove half of the pennies with each shake? Explain why or why not.

CONCLUSION

Sources of error:122

1.

2.


1.

2.


1.

2.





123




Group Rubric:

Poor1 point

Developing2 points

Good3 points

Excellent4 points

Group Rating

TeacherRating


not contribute.


others.





CooperationTeacher


cooperate.




needed.


time.



others when needed.

On taskTeam needs

frequent teacher



the time. Needs

teacher reminders.



reminders.



Communication




Members need some





amounts.




tones.

124

appropriately. other appropriately.



verall

Score on Lab: _____________

Date of Lab: ____________________________________

Question: What is the concentration of Blue 1 food dye in a sample of Gatorade?

Introduction: The goal of this experiment is to determine the concentration of Blue 1 food dye in a sample of Gatorade. You will use a Colorimeter (a side view is shown in Figure 1) to determine the concentration of each solution. In the colorimeter, light from a LED light source will pass through the solution and strike a photocell. A higher concentration of colored solution (higher concentration of dye) absorbs more light than a solution of a lower concentration. The Colorimeter monitors the light received by the photocell as percent transmittance, which is translated into an absorbance.

You will prepare five solutions of known concentrations of Blue 1 dye from a stock solution. In order to create these five solutions (known as standard solutions), you will have to perform dilutions from the stock solution, creating molarities that are within the range of molarity of Blue #1 dye present in the Gatorade solution. Each solution is transferred to a small, rectangular cuvette that is placed into a colorimeter. The amount of light that penetrates the solution and strikes the photocell is used to compute the absorbance of each solution. When you create a graph of absorbance vs. concentration for the standard solutions (see example graph below), a direct relationship should result. The direct relationship between absorbance and concentration for a solution is known as Beer’s Law.

You will determine the concentration of Blue 1 dye in a Gatorade solution by measuring its absorbance with a Colorimeter. By locating the absorbance of the unknown on the vertical axis of the graph, the corresponding concentration can be found on the

125

Lab 20: Beer’s Law—Absorbance of Gatorade

horizontal axis. The concentration can also be found by using the slope of the Beer’s law curve that you determine using your standard solutions.

VARIABLES


Dependent variable:

Constants:HYPOTHESIS*write it as if-then-because statement

EQUATIONSMAVA = MBVB

Molarity = moles of solute Litter of solution

MATERIALS

Vernier Lab Pro Vernier Colorimeter Cuvette Test Tube Rack Test Tubes

Test tube clamp 5 mL pipet Red pipet pump Stock Solution of FD&C Blue 1 Dye

(0.00002 M) Gatorade G2: Blue

PROCEDURE1. Obtain 15 mL of FD&C Blue 1 stock solution from the back of the room. 2. Obtain ~150 mL of distilled water in a beaker. 3. Setup the LabQuest for the Colorimeter 4. Plug the Colorimeter into Ch. 1 on the LabQuest. Set it to 630 nm wavelength. 5. Fill a blank cuvette 3⁄4 full with distilled water. Wipe it dry and place it in the

Colorimeter with the clear side facing the arrow in the Colorimeter. Close the lid. 6. Press the Cal button and wait for the red light to finish flashing. 7. Remove the cuvette and empty the water. This is the only time calibration is

needed. 8. Prepare the first of five standard solutions. Use a pipet to obtain 1 mL of stock

solution and place it in a 25 mL graduated cylinder. Add distilled water to a total volume of 25 mL.

9. Determine the molarity of the diluted solution and record it in the Data Table. 10. Pour the solution into a mixing cup and swirl the solution to ensure that it

126

mixes completely. 11. Use a pipet to fill your cuvette 3⁄4 with the solution. Place in the Colorimeter

and close the lid. 12. Record the absorbance in the Data Table. 13. Repeat steps 4-8 for additional standard solutions. Use 2, 3, 4, and 5 mL of

stock solution and dilute each to 25 mL. 14. Obtain 5 mL of Blue Gatorade in a 10 mL graduated cylinder. Add 5 mL of

distilled water. 15. Pour the solution into a mixing cup and swirl the solution to ensure that it

mixes completely. 16. Fill the cuvette 3⁄4 full with the solution, place in the Colorimeter, and record

the absorbance.

DATA AND CALCULATIONSCalculate the molarity of the original stock solution, which was made with 0.0565 g of Blue 1 in 1400mL of solution. Show all work and units!!

Calculate the molarity of each diluted standard solution and fill in the data table. Show at least one sample calculation for the concentration. (Hint: M1V1 = M2V2)

127

Determine the line equation for the line: ___________________________________________________

DISCUSSION QUESTIONS1. Use the graph/best fit-line to determine the concentration of Blue 1 in the

Gatorade solution.

2. Consider the concentration from #1. The solution was diluted 1:2, so this represents 1⁄2 of the actual molarity. Determine the actual molarity of Blue 1 in the Gatorade solution.

3. Use the internet to research FD&C Blue 1 dye. Write about any side effects, both positive and negative, of consuming this dye.

CONCLUSION

128



2.

Sources of error:1.

2.


1.

2.


2.




129





Group Rubric:

Poor1 point

Developing2 points

Good3 points

Excellent4 points

Group Rating

TeacherRating


not contribute.


others.





CooperationTeacher


cooperate.




needed.


time.



others when needed.

On taskTeam needs

frequent teacher



the time. Needs

teacher reminders.



reminders.



Communication



Members need some






130

to listen to each other


appropriately.

to be able to listen to each



other in equal amounts.


tones.



131

isotopic mass of m & ms - ms. francois' ap chem...

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