1. Do Now/Agenda Work on measurement/sig figs review problems
Today: Finish Unit 1
Next classes: lab and review
Unit 1 Test Thur 9/15 (B), Fri 9/16 (A)

2. Sig Figs Warm Up Don’t round until the very end!
Base your rounded answer off of your given measurements/values.

3. Volume Volume=amount of space an object takes up
Ways we can measure volume:
For liquids: using glassware
When using a graduated cylinder, read the value from the bottom of the meniscus

4. Volume Ways to measure volume
For regular solids: length x width x height

5. Volume Ways to measure volume For irregular solids: water displacement
40 mL
40-20 = 20 mL

6. Density
Density=the amount of mass in a given volume.

7. Which cube has a greater density?
Both cubes take up the same amount of space (volume), but cube A has more matter (mass)

8. Using the Density Formula
mass
density
volume

9. Density Practice: Round answer to proper number of sig figs!
3.23 g/mL
7 g/mL
5 mL
2.0 g/cm3
204 g  2.0 x 102 g
3.23 g/mL, 7.0 g/mL, 5 mL, 6.82 g/mL

10. Accuracy vs. Precision

11. Accuracy vs. Precision
Accuracy=how close the results are to the correct answer (Bull’s eye!)
To determine accuracy, we look at the average of our results.
Precision= how often the same results are measured/obtained
To determine precision, we look at the consistency of our results.

12. AVERAGE
ACCURATE NO

13. each trial/measurement
precise NO

14. Accuracy vs. Precision Practice
YES
YES

15. Accuracy vs. Precision Practice
4.67 NO 99
YES
YES NO

16. Percent Error
A quantitative way we can look at the accuracy of a set of data if the true value is known
For this class, we’ll say the data is accurate if the percent error is less than 5%

17. The freezing point of water is 273. 2 K, but it was measured at 250
The freezing point of water is K, but it was measured at K. What is the percentage error?
Subtract first,
then divide,
then multiply by 100
×100%
250.1− ×100%=
=0.084×100%
=𝟖.𝟒%
NOT ACCURATE

18. Percent Error Practice
2) 4.49 % 3) 888% 4) 3.88%

19. Telephone
602,000,000,000,000,000,000,000
6.02 x 1023

20. Scientific Notation
Scientific notation is used to express very large or ­very small numbers more easily.
It is written as a (decimal between 1 & 10) x 10 raised to an exponent

21. How to express a number in terms of scientific notation:
1. Move the decimal point of your number so that you have a decimal between 1 and 10

22. How to express a number in terms of scientific notation:
2. Count the number of spaces (n) and which direction you moved the decimal point

23. How to express a number in terms of scientific notation:
3. If you moved the decimal point to the left multiply (x) your decimal by 10n
360,000  3.6 x 105
If you moved the decimal point to the right, multiply (x) your decimal by 10—n
 3.7 x 10—4

24. Category
Normal Number
Scientific Notation
Population of the World
7,125,000,000 people
Distance from the Earth to the Moon
240,000 miles
Raindrops in a Thundercloud
6,000,000,000,000 drops
Density of Oxygen
g/cm3
Mass of a Dust Particle kg

25. How to express a value given in scientific notation as a normal number:
1. Identify the exponent
3.6 x 105: exponent 5
3.7 x 10—4: exponent –4

26. How to express a value given in scientific notation as a normal number:
2. If the exponent is a positive number, move the decimal point the same number of places to the right
3.6 x 105: move decimal 5 places to the right

27. How to express a value given in scientific notation as a normal number:
3. If the exponent is a negative number, move the decimal point the same number of places to the left.
3.7 x 10—4: move decimal 4 places to the left

28. Category
Normal Number
Scientific Notation
Speed of Light
3.00 x 108 m/s
Distance from the Earth to the Sun
9.3 x 107 miles
Cells in the Human Body
1.0 x cells
Water on Earth’s Surface
1.40 x 108 square miles
Diameter of a Grain of Sand
2.4 x inches

29. Homework
Accuracy, Precision, Density