c: 22 september 2011
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C: 22 September 2011. Take Out Homework : W eek 3 #1-5 and Lab Report Objective : You will be able to: differentiate between accurate and precise measurements determine the number of significant figures in any value - PowerPoint PPT PresentationTRANSCRIPT
C: 22 September 2011
Take Out Homework: W eek 3 #1-5 and Lab Report
Objective: You will be able to: differentiate between accurate and
precise measurements determine the number of significant
figures in any value Do now: Calculate the mass of a pure
copper penny (density = 8.92 g/cm3) with a volume of 0.20 cm3.
Agenda
I. Do nowII. Track objective masteryIII. Go over homeworkIV. Accuracy vs. precision notes and
examplesV. Practice problemsVI. Significant figures rules and examplesVII. Clicker practice problemsHomework: Week 3 Homework #6-10: Fri.
Track Objective Mastery
Objective 8 (Density) Exit Ticket Unit 1 Pretest B Objectives 5-12
Where have you improved most?!
Density Exit Ticket
II. b. Calculate the volume of a piece of gold (density = 19.32 g/cm3) that has a mass of 5.00 grams.
Expectations
During notes and example problems: silently write them into your notebook Raise your hand to ask questions
or make comments
Reading a graduated cylinder
Precision and Accuracy
precision: how close a series of measurements are to each other.
accuracy: how close a series of measurements are to the actual or true value.
Volume of a sample of water(Actual volume: 5 mL)
a. 2.0 mL, 2.1 mL, 1.9 mLb. 4.0 mL, 5.0 mL, 6.0 mLc. 1.2 mL, 5.5 mL, 10.6 mLd. 4.9 mL, 5.0 mL, 5.0 mL
Mass of copper cylinder (g)
Larissa Loveng LorrenoMassing 1
47.45 47.95 47.13
Massing 2
47.39 47.91 47.94
Massing 3
47.42 47.89 46.83
Massing 4
47.41 47.93 47.47Three students made multiple weighings of a copper cylinder, each using a different balance. The correct mass of the cylinder had previously been determined to be 47.32 grams. Comment on the accuracy and precision of each student’s measurements.
Comment on the accuracy and precision of these basketball free-throw shooters: a. 99 of 100 shots are made b. 99 of 100 shots hit the front of
the rim and bounce off c. 33 of 100 shots are made, the
rest miss.
SWBAT determine the precision and accuracy of data.
On Your Own
a. How are accuracy and precision similar?
b. How are accuracy and precision different?
c. Give an example of a data set that is very precise but not accurate. (Hint: You’ll have to write down the “real” answer, too.)
Percent Error: a measurement of how accurate your data are
100_
__
valueactual
valueactualvalueyour
1. So, if the actual value is 5.0 grams, but your average mass was 4.6 grams, what is your percent error?
2. What if your average volume was 25.0 mL, but the actual value is 23.9?
An engineer was responsible for calculating amount of water that overflowed from a dam. He measured all of the water runoff going into the reservoir (1.2 million cubic feet per year), the rainfall (860 cubic feet per year), and the capacity of the reservoir (3.8 million cubic feet). He did some fancy calculations. He reported to his boss that the overflow from the dam would be 350,246.2544330 cubic feet per year.
What’s wrong here?
Significant Figures
How to determine how accurate a number is
How to determine how much to round an answer
I. Significant Figuresaka: Significant Digits
A. Nonzero integers count as significant figures Ex. Any number that is NOT zero (1, 2, 3, 4,
5, 6, 7, 8, 9) 345 597.2 145.456
SWBAT identify and round a number to the correct number of significant figures.
Zeros B. Leading zeros that come before all the
nonzero digits do NOT count as significant figures
Ex: 0.0025 has two sig. fig. The zeros are “leading” and do not count.
0.23 0.0004 0.03564
SWBAT identify and round a number to the correct number of significant figures.
C. Captive zeros are between nonzero digits and DO count as sig. fig.
Ex: 1.008 has four sig. fig. The zeros are captive and DO count.
10,004 1.000006 1,000,000,000,000,567
SWBAT identify and round a number to the correct number of significant figures.
D. Trailing zeros are to the right end of the number and DO count as sig. fig. if the number contains a decimal point.
Ex.: 100 has only one sig. fig. because the trailing zeros DO NOT have a decimal point.
Example: 1.00 has three sig. fig. because the trailing zeros DO have a decimal point.
SWBAT identify and round a number to the correct number of significant figures.
More practice: Trailing zeros
1.000000 3,000,000 3.00000 30.00 300 300.
E. Exact numbers Any number found by counting has an
infinite number of significant figures. Ex: I have 3 apples. The 3 has an infinite
number of significant figures. 50 people 100 baseballs
SWBAT identify and round a number to the correct number of significant figures.
Which are exact numbers?
1. The elevation of Breckenridge, Colorado is 9600 feet.
2. There are 12 eggs in a dozen.3. One yard is equal to 0.9144 meters.4. The attendance at a football game was
52,806 people.5. The budget deficit of the US
government in 1990 was $269 billion.6. The beaker held 25.6 mL of water.
SWBAT identify and round a number to the correct number of significant figures.
Clicker Use
Always pick up and use only your assigned clicker: You are responsible for it!
Remain silent while the question is being read and while you answer – only answer for yourself!
Never laugh at, mock or ridicule the proportion of students answering incorrectly.
Listen carefully as the answer is explained.
How many significant figures? 256
1 2 3 4
0%5%
95%
0%
1. 12. 23. 34. 4
SWBAT identify and round a number to the correct number of significant figures.
How many significant figures? 647.9
1 2 3 4
5%
95%
0%0%
1. 12. 23. 34. 4
SWBAT identify and round a number to the correct number of significant figures.
How many significant figures? 647.0
1 2 3 4
0%
73%
27%
0%
1. 12. 23. 34. 4
SWBAT identify and round a number to the correct number of significant figures.
How many significant figures? 321.00
1 2 3 4
6%
94%
0%0%
1. 22. 33. 44. 5
SWBAT identify and round a number to the correct number of significant figures.
How many significant figures? 4005
1 2 3 4
0%
86%
0%
14%
1. 12. 23. 34. 4
SWBAT identify and round a number to the correct number of significant figures.
How many significant figures? nine
1 2 3 4
33%
67%
0%0%
1. 12. 23. 34. infinite
SWBAT identify and round a number to the correct number of significant figures.
How many significant figures? 200.
1 2 3 4
5%14%
82%
0%
1. 12. 23. 34. 4
SWBAT identify and round a number to the correct number of significant figures.
How many significant figures? 200.0
1 2 3 4
0%
100%
0%0%
1. 12. 23. 34. 4
SWBAT identify and round a number to the correct number of significant figures.
How many significant figures? 0.009009
1 2 3 4
0%
58%
0%
42%
1. 22. 43. 64. 7
SWBAT identify and round a number to the correct number of significant figures.
How many significant figures? -500
1 2 3 4
57%
0%
43%
0%
1. 12. 23. 34. 4
SWBAT identify and round a number to the correct number of significant figures.
How many significant figures? -500.
1 2 3 4
0% 0%
100%
0%
1. 12. 23. 34. 4
SWBAT identify and round a number to the correct number of significant figures.
How many significant figures? 1.3x1032
1. 12. 23. 34. 4
SWBAT identify and round a number to the correct number of significant figures.
How many significant figures?
1. A student’s extraction procedure yields 0.0105 g of caffeine.
2. A chemist records a mass of 0.050080 g in an analysis.
3. In an experiment, a span of time is determined to be 8.050 x 10-3 s.
4. Rewrite 8.050 x 10-3 so it has three significant figures.
SWBAT identify and round a number to the correct number of significant figures.
Assignment
In your lab notebook, find the density stations from yesterday.
Next to each value you measured, write the number of significant figures in a circle. Ex: 12.35 cm 4
Exit Ticket
Homework
Week 3 Homework #6-10: Fri.
C: 23 September 2011
RoundingTake Out Homework: Week 3 Homework
#1-10 Objective: You will be able to:
round values to the correct number of significant figures
Do now: How many significant figures? a. 0.00045 b. 0.00040 c. 0.0004050
Agenda
I. Do nowII. Go over homeworkIII. Accuracy/Precision, Sig. Fig. “Exit”
TicketIV. Rounding Notes and ExamplesV. Practice ProblemsVI. Exit TicketHomework: Week 3 Homework #11-14:
Mon.
“Exit” Ticket
Precision/Accuracy Sig. Fig.
Rounding
The answer to a calculation can not be any more accurate than the least accurate value in that calculation.
When multiplying or dividing, round to the least number of significant figures given in the problem.
Example 1
An iron block with side lengths 10.5 cm by 22.6 cm by 2.5 cm has a mass of 4655 grams. Calculate the density of iron.
Example 2
The density of mercury is 13.53 g/cm3. Calculate the volume taken up by 5.0 grams of mercury.
Problems
1. Calculate the mass of a cube of silver with side length 5.0 cm. Silver has a density of 10.49 g/cm3.
2. Calculate the density of a stack of gold coins with mass 1100 grams and volume of 51.76 cm3.
Exit Ticket
Rounding
Homework
Week 3 Homework #11-14: Monday
C: 28 September 2011
Objective: You will be able to: round a calculation to the correct
number of sig. fig. plan a procedure and data table
for a lab on the density of pennies Do now: Round to TWO sig. fig:
a. 0.003563725b. 5,723
Agenda
I. Do nowII. Tracking Objectives – RoundingIII. Rounding WorksheetIV. Pennies lab: Plan procedureV. Design a data tableHomework: Quiz Friday: Objectives
8-11
Tracking Objectives
Rounding Exit Ticket: Objective 11
Rounding Practice (10 min.)
Quietly, on your own If you have a question, you may
consult your partner or raise your hand to ask me a question.
When you are done, have me check your work.
Then, complete the exit ticket on your own.
With your lab group (20 min.)
In your notebook: Copy the research questions Make two hypotheses (one for
each research question) On the poster paper as a group:
Write your complete and detailed procedure
Gallery Walk (8 min.)
With a marker, read another group’s procedure.
Make constructive comments in writing “How big is the graduated
cylinder?” “I like how you were specific about
what to change in each trial!” Then, visit another group’s poster
and do the same thing.
Together:
Construct the procedure we will all follow from the best elements of everyone’s group posters.
As a lab group
Design your data table for next class!
Homework
Quiz Friday: Objectives 8-11 Finish Procedure
A: 27 September 2011
Objective: You will be able to: determine the relationship between
mass and volume of pennies. compare the density of pre- and
post-1982 pennies. Do now: Round to THREE sig. fig:
a. 0.003549248b. 356,908,256
Agenda
I. Do nowII. Tracking ObjectivesIII. Carry out your procedure and collect
data!IV. Finish calculationsHomework: Finish Unit 1 Pretest B:
tomorrowBe sure all your density calculations are
done.Objectives 8 through 11 quiz tomorrow
Track Quiz and Exit Ticket
Did you get less than a 3 or 4 on Objectives 1 through 4? Come for extra help after school! Re-take a quiz on that objective
after school or next time we have a quiz.
Your goal is to earn a 3 or a 4 for EVERY objective!!
Carry out your procedure
Split up the work to be most efficient. Work carefully. Estimate the last digit on the
graduated cylinder. Neatly record your data in a table in
your notebook. Make sure your station looks as neat
when you are finished as it did when you started!
Equipment
250 mL beaker vinegar 100 mL graduated cylinder electronic balance water
Homework
Be sure all your density calculations are done.
Objectives 8-11 Quiz Thursday (study exit tickets!)
We’ll finish this lab tomorrow!
C: 30 September 2011
Objective: You will be able to: show what you know about
objectives 8-11. Do now:
Look at your tracking sheet Quiz grades for objectives 1-4. Write down the number of any objectives you have not yet earned a 3 or 4 on.
Agenda
I. Do nowII. Track Rounding (Obj. 11) exit ticket 2III. Objectives 8-11 Quiz!IV. Make up Objectives 1-4 QuizzesV. Work on lab graph, analysis and
conclusionHomework: Week 4 Homework p. 1: Mon.Lab graph, analysis and conclusion: due
Monday
Properties
Intensive: the property does NOT depend on the amount of stuff you have ex: temperature
Extensive: the property DOES depend on the amount of stuff you have ex: mass
Use your data to determine if density is an intensive property or an extensive property!
Track Rounding (Obj. 11)
You can erase/cross out your first exit ticket score if you earned a higher score!
When you finish your quiz…
Raise your hand and tell me if you need to retake any objective 1-4 quizzes.
Once you are done with quizzes, work on graphing your data, writing an analysis and conclusion Look at the lab handout for all the
details! Work on this silently until everyone
is done with their quizzes.
Need help on the lab?
Need extra help before you retake a quiz?
Work with me after school Monday!
Homework
Lab notebook: Monday Week 4 Homework p. 1: Mon.
C: 29 September 2011
Homework: Density of Pennies Procedure
Objective: You will be able to: determine the relationship between
mass and volume of pennies and compare density
Convert between scientific and regular notation.
Do now: Read through your procedure. Write down one question you have about it to share with your lab group.
Agenda
I. Do nowII. Carry out your procedure and collect data!III. Finish calculations and graph dataIV. Graph DataV. Scientific notation notes and practiceHomework: Week 4 Homework page 1: Mon.Pennies lab analysis and conclusion: MondayObjectives 8 through 11 quiz tomorrow
By 9:15…
1. Collect your data and organize it into the nicest table you have ever made
See the lab handout for more details.2. Graph both data sets on one set of
axes – this should be the nicest graph you have ever made
See the lab handout for more details. Complete the analysis and conclusion
in your lab notebook.
Scientific Notation
Homework
Pennies lab analysis and conclusion: Friday
Objectives 8 through 11 quiz tomorrow
The sample of gold contained 1,200,000,000,000,000,000,000,000,000 atoms.
How do we keep track of ALL those zeros?
In chemistry, some numbers are HUGE!
III. Rules for Sig. Fig. in Mathematical Operations
A. Multiplication and Division The number of sig. fig. in the results should
be the same as the number of sig. fig. in the least precise measurement used in the calculation.
Example: 4.56 x 1.4 = 6.38 6.4
B. Addition and Subtraction The result should have the same number of
decimal places as the least precise measurement used in the calculation.
Example: 12.11 + 18.0 + 1.013 = 31.123 31.1 (one decimal place)
13 x 1.000 = 13.000 = 23.45 x 400 = 9380 = 5000 / 3.12 = 1602.56410256…
14 + 3.567 = 17.567
56.2 + 23.988 = 80.188
100 – 1.9995 = 98.0005
IV. Rounding
Calculate first, then round Example: round 4.348 to two sig. fig.
4.3 Never round until your final answer!
Converting between SI units
notes from the board
SWBAT convert between units in the SI system.
SI Unit Prefixes
Steps to Conversions
1. Identify and write your known and unknown.
2. Choose an equality.3. Make a fraction4. Put units to cancel on the bottom5. Put units to remain on the top6. Cancel units and compute7. Report answer with units!
Practice Problems
1 liter = 1000 milliliters1. How many liters are equal to 550
milliliters?2. How many milliliters are equal to 3.5
liters?3. How many liters are equal to 45,000
milliliters?4. How many milliliters are equal to
354 liters?SWBAT convert between units in the SI system.
1 meter = 100 cm, 1 kilometer = 1000 meters1. How many meters are equal to 500
centimeters?2. How many centimeters are equal to 850
meters?3. How many meters are equal to 37.5
kilometers?4. How many centimeters are equal to 5.8
kilometers?
SWBAT convert between units in the SI system.