Unit 2:

Energy

(Chapter 15)

Name

Class Color:

Vocabulary:

Reactant- Product

__________________________________________

Joule/calorieEnergy

__________________________________________

SublimationEvaporation

__________________________________________

DepositionMelting

__________________________________________

FreezingCondensation

__________________________________________

ExothermicEndothermic

__________________________________________

HeatLaw of conservation of energy

__________________________________________

Kinetic energyTemperature

__________________________________________

Specific heatHeat of fusion

__________________________________________

Heat of vaporizationThermochemistry

__________________________________________

Unit 2 Energy:

Enduring Understanding: Matter is classified by its structure and how it reacts.

Essential Questions: How can you describe matter? Why do things behave the way they do?

Goals: I Can:

1. Distinguish between endothermic and exothermic reaction processes.

2. State that chemical and physical changes can be exothermic or endothermic.

3. List the three phases of matter, and use a simple particle model to differentiate among properties of solids, liquids, and gases.

4. Explain phase changes in terms of the changes in energy and intermolecular distances.

5. State that energy can exist in different forms, such as chemical, electrical, electromagnetic, thermal, mechanical, and nuclear.

6. State that heat is a transfer of energy (usually thermal) from a body of higher temperature to a body of lower temperature.

7. State that thermal energy is associated with the random motion of atoms and molecules.

8. State that temperature is a measure of average kinetic energy of the particles in a sample of matter (not a form of energy). Temperature is measured in degrees Celsius, heat energy in Joules.

9. Distinguish between heat energy and temperature in terms of molecular motion and amount of matter.

10. Qualitatively interpret heating and cooling curves in terms of changes in kinetic and potential energy, heat of vaporization, heat of fusion, and phase changes.

11. Calculate the heat involved in a phase change or temperature change for a given sample of matter.

Calendar for unit 2 Regents Chemistry: Red (2 & 3A) and Yellow (9 &8A) classes

10/9

10

11

12

13

E

S

A

B

Columbus day

NO SCHOOL!

Review/Make Up Day

HW: Study for test

Unit 1 Test

Topic 2.1 Temperature versus heat

HW: Assignment #1 practice with heat & temperature

Topic 2.2 & 2.3 Phase changes & Heating and Cooling curves

Chemistry work period

Chemistry work period

16

17

18

19

20

C

D

E

S

A

Topic 2.2 & 2.3 Phase changes & Heating and Cooling curves

HW: Assignment #2 practice with 2.2 & 2.3 for quiz review

Quiz 2.1-2.3

Topic 2.4 Calorimetry and Q=mc∆T

HW: Assignment #3

Topic 2.5 Heat of Fusion and Vaporization

HW: Assignment #4

Heat Calculations Practice

Quick Quiz on Heat calculations

Lab 2.1

Lab 2.2

Chemistry work period

23

24

25

26

27

B

C

D

E

S

Review/Make up Day

Test Unit 2

HW: History of the atom introduction

Unit 3 begins! See next unit notes for this calendar!

Chemistry work period

Calendar for unit 2 Regents Chemistry: Blue (5 & 4B) and Green (7 & 8B) Classes:

10/9

10

11

12

13

E

S

A

B

Columbus day

NO SCHOOL!

Review/Make Up Day

HW: Study for test

Unit 1 Test

Topic 2.1 Temperature versus heat

HW: Assignment #1 practice with heat & temperature

Topic 2.2 & 2.3 Phase changes & Heating and Cooling curves

Chemistry work period

Chemistry work period*

16

17

18

19

20

C

D

E

S

A

Topic 2.2 & 2.3 Phase changes & Heating and Cooling curves

HW: Assignment #2 practice with 2.2 & 2.3 for quiz review

Quiz 2.1-2.3

Topic 2.4 Calorimetry and Q=mc∆T

HW: Assignment #3

Topic 2.5 Heat of Fusion and Vaporization

HW: Assignment #4

Heat Calculations Practice

Quick Quiz on Heat calculations

Lab 2.1*

Lab 2.2

23

24

25

26

27

B

C

D

E

S

Review/Make up Day

Test Unit 2

HW: History of the atom introduction

Unit 3 begins! See next unit notes for this calendar!

Chemistry work period

(Topic 2.1)Heat and Temperature:

What’s the difference between heat and temperature?

Temperature: is the _______________________________________________________. At absolute zero, particle motion __________, and so the particles (atoms or molecules) have no __________ __________.

Temperature is measured in _____ (Centigrade), or in __________. The __________ is the absolute temperature scale, with no negative numbers. To convert between the two scales, add ______ to the Celsius temperature or subtract ______ from the Kelvin scale. The Kelvin temperature is always __________ than the Celsius temperature.

How do the scales work?

1. What 2 physical points were used to develop the Fahrenheit and Celsius Temperature Scales?

2. What is the difference between the Celsius Temperature scale and the Absolute Kelvin Temperature scale?

3. What is the significance of Absolute Zero?

4. Why is it appropriate to compare the Absolute Kelvin Temperature scale to a speedometer?

Heat is a .

Two types of energy

Kinetic energy-______________________________________________________

Potential energy-____________________________________________________ __________________________________________________________________

Units for heat is . NEVER .

Two important things to know about heat:

Drop of H2O 100oCBeaker filled with 100 mL of H2O 100oC

(Object B 100oC)

(Object A 50oC)

Heat capacity – the amount of __________ needed to raise the temperature of an object 1 o C.

Greater the mass the greater the heat capacity. (thermal energy is ____________ in objects with a ___________________ mass.

Ex: 1 cup of water has a higher heat capacity than a drop of water

1 steel I-beam has a greater heat capacity than a steel nail.

(ASSIGN.#1)Temperature and Heat Flow

Practice

1. In which sample do the particles have the lowest average kinetic energy?

(1) H2O (l) @ 55 oC(3) NaCl(aq)@ 30 oC

(2) Br2 (l)@ 75 oC(4) Mg (s)@ 17 oC

2. Draw an arrow to represent the direction of heat flow in the diagram below. Show it pointing the correct direction, and position it to show where the heat transfer is occurring. Size of the shapes represents the amount (mass) of the samples.

(55 oC)

Sample B

(70 oC) (Sample A)

3. Explain how or why the statements below are true, based on your knowledge of heat and temperature.

A) Sample A in the diagram above contains particles with a higher speed than those in Sample B.

___________________________________________________________________

___________________________________________________________________

B) If we cut Sample B in half, each half would have half the original heat content.

___________________________________________________________________

___________________________________________________________________

C) If we cut Sample B in half, each half would still have a temperature of 55 oC.

___________________________________________________________________

___________________________________________________________________

D) Even though Sample B is at a lower temperature, it could contain more heat than Sample A.

___________________________________________________________________

___________________________________________________________________

5. (REGENTS QUESTION!) Object A at 80.°C and object B at 40.°C are placed in contact with each other. Which statement describes the heat flow between the objects?

10

(1) Heat flows from object A to object B.

(2) Heat flows from object B to object A.

(3) Heat flows in both directions between the objects.

(4) No heat flow occurs between the objects.

(Topic 2.2 & 2.3)

Phase changes & Heating and Cooling curves POGIL (see ancillary packet)

How does adding or removing energy from a substance change its physical properties? How can a graph show the relationship between particle motion and heat?

Both physical and chemical changes can be _____________ or _____________.

***In an exothermic process, heat is released, and the container should feel hot.

Exo- __________q= ____

***In an endothermic process, heat is absorbed, and the container should feel cold.

Endo- __________q= ____

Sublimation is a change directly from __________ to gas. Deposition is a change directly from a gas to __________. They are opposites, just as boiling and __________ are opposites.

Questions

1) A container of melted paraffin wax was allowed to stand at room temperature until the wax solidified. What is the direction of heat flow as the liquid wax solidifies? Is the process exo or endothermic?

2) When solid barium octahydrate (Ba(OH)2*8H2O) is mixed in a beaker with solid ammonium thiocyanate (NH4SCN), a Rx occurs. The beaker quickly becomes very cold. Is the Reaction exo or endothermic?

(Topic 2.2 & 2.3 continued)

On the heating curve, label each segment by what phase(s) are present during that segment. Label heat of fusion and heat of vaporization on the energy axis.

Kinetic energy is increasing during segments ____________________.

Potential energy is increasing during segments ____________________.

Phase changes that are exothermic include ______________________________.

(__________________________________________________)

Phase changes that are endothermic include ______________________________.

(__________________________________________________)

On the diagram, label the direction of exothermic change and the direction of endothermic change.

(ASSIGN.#2)Phase Changes & Energy

Regents Practice

1. What occurs when a substance freezes?

(1) It changes from solid to liquid, and heat is absorbed

(2) It changes from solid to liquid, and heat is released

(3) It changes from liquid to solid, and heat is absorbed

(4) It changes from liquid to solid, and heat is released

2. The phase change represented by the equation

I2(s) I2(g) is called

(1) Sublimation

(2) Condensation

(3) Melting

(4) Boiling

3. A gas changes directly to a solid during

(1) Fusion

(2) Deposition

(3) Sublimation

(4) Decomposition

4. At which Celsius temperature does lead change from a solid to a liquid? (Where might your look to help you on this problem?) Show work

(1) 873C

(2) 600C

(3) 328C

(4) 0C

5. The freezing point of bromine is (Where might your look to help you on this problem?) Show work

(1) 539C

(2) -539C

(3) 7C

(4) -7C

6. Which phase change is endothermic? (explain why)

(1) H2O(ℓ) H2O(g)

(2) I2(g) I2(s)

(3) Hg(ℓ) Hg(s)

(4) H2S(g) H2S(ℓ)

7. Which phase change at STP represents sublimation?

(1) Hg(ℓ) Hg(s)

(2) H2O(s) H2O(g)

(3) NH3(g) NH3(ℓ)

(4) CH4(ℓ) CH4(g)

10

A few pieces of dry ice, CO2(s), at -78C are placed in a flask that contains air at 21C. The flask is sealed by placing an uninflated balloon over the mouth of the flask. As the balloon inflates, the dry ice disappears and no liquid is observed in the flask.

8. Write the name of the process that occurs as the dry ice undergoes a phase change in the flask.

______________________________________________________________________________________________________________________________________________________________________________

9. State the direction of heat flow that occurs between the dry ice and the air in the flask.

______________________________________________________________________________________________________________________________________________________________________________

(ASSIGN. #2.5#3)Heating and Cooling Curves

Practice for quiz 2.1

10.

11

Answer the following questions using the chart above.

1. What is the freezing point of the substance? __________

2. What is the boiling point of the substance? __________

3. What is the melting point of the substance? __________

4. What letter represents range where the solid is being warmed? __________

5. What letter represents the range where liquid being warmed? __________

6. What letter represents the range where the vapor being warmed? __________

7. What letter represents the melting of the solid? __________

8. What letter represents the vaporization of the liquid? __________

9. What letter(s) shows a change in potential energy? __________________________________________________

10. What letter(s) shows a change in kinetic energy? __________________________________________________

11. What letter represents condensation? __________

12. The segment where heat is added, and might be called the “Heat of Fusion.” __________

13. Could the substance being heated be water? Explain why or why not.

(ASSIGN. #2.5 con’t#3)

14. Which process is exothermic? (What could you DRAW and model to help you answer this question?)

(1) boiling of water(3) condensation of ethanol vapor

(2) melting of copper(4) sublimation of iodine

Base your answers to questions 15 and 16 on the information below.

Starting as a gas at 206°C, a sample of a substance is allowed to cool for 16 minutes. This process is represented by the cooling curve below.

15) What is the boiling point of this substance? _____________

16) At what time do the particles of this sample have the lowest average kinetic energy? ____________

Base your answers to questions 9 and 10 on the information below.

A phase change for carbon dioxide that occurs spontaneously at 20.°C and 1.0 atmosphere is represented by the balanced equation:CO2(s) + energy CO2(g)

17) Write the name of this phase change. ________________________

18) Describe what happens to the potential energy of the CO2 molecules as this phase change occurs.

Base your answers to questions 19 through 20 on the information below.

A 100.0-gram sample of NaCl(s) has an initial temperature of 0°C. A chemist measures the temperature of the sample as it is heated. Heat is not added at a constant rate. The heating curve for the sample is shown below.

19) Determine the temperature range over which the entire NaCl sample is a liquid.

20) Identify one line segment on the curve where the average kinetic energy of the particles of the NaCl sample is changing.

(TOPIC 2.4)HEAT EQUATIONS

How can we quantify heat required for a temperature change?

Darken the areas of the heating curve where the temperature is changing. In these areas, the amount of heat you need to add is dependent on 3 things:

1.

2.

3.

The equation Q= mc∆T is used when the temperature of the sample changes. (Note the ∆T term in the equation).

Specific heat: Tells us the amount of _____________ (_________) needed to raise 1 gram of a substance 1 Kelvin (or 1 )

· A large/high specific heat means it takes ______________ of energy for the temperature to change

· A small/low specific heat means it only takes a _________________ amount of energy for the temperature to change

THE EQUATION YOU NEED: q = mC∆T

Use the selection from the reference table to figure out the symbols:

1. What does q stand for? ________________________________________________________________

2. What does m stand for? ________________________________________________________________

3. What does C stand for? ________________________________________________________________

4. What does ∆T stand for? _______________________________________________________________

Practice problem: How much heat is required to raise the temperature of 250.0 g of water by 52 oC? As can be seen in Table B, the specific heat capacity of water is _____________________.

(ASSIGN.#3)Calculating Heat

Practice

18

14

1) How much heat is needed to raise the temperature of 20 grams of liquid water from 10 ⁰C to 20 ⁰C?

2) Consider the following data:

Mass (g)

Heat Added (kJ)

∆T (°C)

Aluminum

100

1000

11.3

Water

100

1000

2.4

Explain why temperature changes more with aluminum than with the water. ______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

3) What is the amount of heat energy released when 51.0 grams of water is cooled from 20.0°C to 10.0°C?

(1)

(2) 5.00 x 102 J

(3) 2.13 x 103 J

(4) 4.26 x 104 J

(5) 1.13 x 106 J

4) What is the total amount of heat energy, in joules, absorbed by 25.0 grams of water when the temperature of the water increases from 24.0°C to 38.0°C?

A 7.00-gram sample of liquid ammonia is originally at 210. K. The diagram of the partial heating curve below represents the vaporization of the sample of ammonia at standard pressure due to the addition of heat. The heat is not added at a constant rate. Some physical constants for ammonia are shown in the data table below.

5) In the space below, calculate the total heat absorbed by the 7.00-gram sample of ammonia during time interval AB. Your response must include both a correct numerical setup and the calculated result.

6) Describe what is happening to both the potential energy and the average kinetic energy of the molecules in the ammonia sample during time interval BC. Your response must include both potential energy and average kinetic energy.

(TOPIC 2.5)HEAT OF FUSION & VAPORIZATION

How can we quantify heat required for a phase change?

We’ve seen and represented the change in particle spacing and motion when heat is added to a sample of matter. What we haven’t done is calculated just how much heat is needed to bring about those changes.

Darken the areas of the heating curve where the phase of matter is changing.

In these areas, the amount of heat you need to add is dependent on only 2 things:

1. The mass of the substance (how much stuff do you have?)

2. How hard it is for the substance to change phase

· Heat of fusion:

· Heat of vaporization:

THE EQUATION YOU NEED: q = mHf OR q = mHv

Use the selection from the reference table to figure out the symbols:

1. What does q stand for? ________________________________________________________________

2. What does Hf stand for? ________________________________________________________________

· You will use Hf for melting/freezing problems.

3. What does Hv stand for? _______________________________________________________________

· You will use Hv for evaporation/condensation problems.

The equations Q=mHf and Q=mHv are used when temperature (circle one: does or does not) change.

At what temperature does ice freeze? ________ melt? ______

At what temperature does water boil? ________ condense? ______

****Big idea: ENERGY can not be _____________________ or _______________________ only transformed. (Law of ___________________________________________________________).

Solve the following:

1. 100. g of water at 30oC is heated to 50oC. How much heat was absorbed?

Formula to use:

Work:

2. 50. grams of water melts at 0o C. How much heat is gained?

Formula to use:

Work:

3. 100. grams of water condenses to a liquid at 100o C. How much heat is lost?

Formula to use:

Work:

4. What is the total number of joules of heat energy absorbed when the temperature of 200.g of water is raised from 10.0 oC to 40.0oC?

Formula to use:

Work:

5. What is the total kilojoules of heat needed to change 150.g of ice to water at 0oC?

Formula to use:

Work:

(ASSIGN.#4)Calculating Heat – Phase Changes

Regents Practice

18

18

Base your answer to question 1 and 2 on the information below.

A student performs an experiment where heat is added to a 200.-gram sample of H2O(s) to melt the sample at 0°C. Then the resulting H2O(ℓ) is heated to a final temperature of 65°C.

1.) Compare the amount of heat required to vaporize a 200.-gram sample of H2O(ℓ) at its boiling point to the amount of heat required to melt a 200.-gram sample of H2O(s) at its melting point. (HINT: determine the amount of heat required to melt and then the heat to boil using the appropriate equation and then compare).

2.) Based on data collected during the laboratory investigation, the student determined an experimental value of 322 joules per gram for the heat of fusion of H2O. Calculate the student’s percent error. Your response must include a correct numerical setup and the calculated result.

Base your answer to questions 3 through 5 on the information below.

Carbon dioxide is a colorless, odorless gas at room temperature. At standard temperature and pressure, CO2(s) changes directly to CO2(g). Carbon disulfide is formed by a direct reaction of carbon and sulfur. At room temperature, CS2 is a colorless liquid with an offensive odor. Carbon disulfide vapors are flammable.

3.) Identify one physical property and one chemical property of CS2.

a. Physical

b. Chemical

4.) State what happens to the potential energy of CO2 molecules during this phase change of CO2.

5.) Compare the intermolecular forces in CO2 and CS2 at room temperature. (Hint: What state of matter are they at room temperature? Use that to help answer the question.)

6.) What is the total amount of heat required to vaporize 1.00 gram of H2O(ℓ) at 100.°C and 1 atmosphere?

(1) 4.18 J (3) 373 J

(2) 334 J (4) 2260 J

Base your answers to questions 7 through 9 on the diagram below.

7.) Describe what happens to both the potential energy and the average kinetic energy of the molecules in the H2O sample during interval AB.

8.) Using the graph, determine the total amount of heat added to the sample during interval CD.

9) Explain, in terms of heat of fusion and heat of vaporization, why the heat added during interval DE is greater than the heat added during interval BC for this sample of water

Practice with heat formulas

1. If you have a sample of 30g of water at 100oC, how much heat does it take for complete vaporization?

Formula to use:

Work:

2. If you have 60g of mercury that is placed into water and changes from 70oC to 25oC and releases 342 J of heat, what is the specific heat of mercury?

Formula to use:

Work:

3. You are given that the heat of fusion of a sample of 22g of lead is 21434J/g, what is the heat gained by the system as the lead goes from the solid phase to the liquid phase?

Formula to use:

Work:

4. What is the mass of a sample of magnesium that has a specific heat value of 3.2J/goC, changes the temperature of the water 434J of heat is absorbed?

Formula to use:

Work:

5. Draw a heating curve below and label ONLY the phase changes and what happens to kinetic energy on each segment.

Word Bank- vocabulary review

(EnergyVaporizationKinetic energyBoiling PointPotential energyCondensationHeat of fusion Heat of vaporizationSublimationExothermicFusionEndothermicDepositionJouleSolidificationCalorimetry)

Fill in the blank below:

1. The ___________________________ is the SI unit of measurement for any type of energy.

2. Gasses have the highest ____________________________ of all the three states because its particles are in fast and constant motion.

3. The ___________________________ for water is 100 C.

4. ____________________________ is represented by a change from ice to liquid water.

5. Dry ice exhibits _____________________________ because it changes from a solid directly into a gas.

6. Melting is an example of an __________________________ change because energy needs to be absorbed during the process.

7. Water forming on a cold window is an example of ___________________________ as water vapor changes into a liquid.

8. An _______________________________ change is one that involves a release of energy by the system.

9. Fire extinguishers exhibit ____________________________ as the gas inside changes directly to a solid powder.

10. ______________________________ is the measurement of the amount of heat released or absorbed during a chemical reaction.

11. Amount of energy absorbed or released when a substance is boiled or condensed is defined as the _________________________________.

12. Amount of energy absorbed or released when a substance is melted or solidified is defined as the _________________________________.

UNIT 2 TEST REVIEW CHECKLIST

Identify where to focus/how to spend your time during this review in class.

Unit Learning Target

YES. Got it.

Needs review

NOPE. Not yet.

1

I can distinguish between endothermic and exothermic reaction processes.

2

I can state that chemical and physical changes can be exothermic or endothermic.

3

I can list the three phases of matter, and use a simple particle model to differentiate among properties of solids, liquids, and gases.

4

I can explain phase changes in terms of changes in energy and intermolecular distances.

5

I can state that energy can exist in different forms, such as chemical, electrical, electromagnetic, thermal, mechanical, and nuclear.

6

I can state that heat is a transfer of energy (usually thermal) from a body of higher temperature to a body of lower temperature.

7

I can state that temperature is a measure of average kinetic energy of the particles in a sample of matter (not a form of energy). Temperature is measured in degrees Celsius, heat energy in Joules.

8

I can distinguish between heat energy & temperature in terms of particle motion and amount of matter.

9

I can qualitatively interpret heating and cooling curves in terms of changes in kinetic and potential energy, heat of vaporization, heat of fusion, phases and phase changes.

10

I can calculate the heat involved in a phase change or temperature change for a given sample of matter.