1. Homework Read Pgs. 11-13 Chapter 1 Problems 20, 24, 26,30
Worksheet Scientific Measurement (2A Extra Practice Problems)

2. Addition and Subtraction
Significant figures
Addition and Subtraction
The answer must have the same number of decimal places as the factor with the least number of decimal places.

3. Significant Figures
Example of Addition: (this is what a calculator will show) 1274 (this is the answer corrected for significant figures, rounded to the 1’s place)

4. Multiplication and division
Significant figures
Multiplication and division
The answer must have the same number of significant figures as the factor with the least number of significant figures.

5. Example of Division: Significant figures 15.375 / 5.0 = 3.075
(this is what a calculator will show)
Since the denominator only has 2 significant figures the answer is rounded to 3.1

6. Significant Figures 8.654 m x 0.34 m = 2.10 cm x 0.50 cm =
ml ÷ 8.4 ml =
0.365 m ÷ m =

7. textbook HW
20a. 3 26a g b. 4 b cm c. 4 c. 13 lb d. 1 d. 350 oz e only c is exact 24a. 0.5 b c d. 7.8

8. Scientific Measurement
1 a a. 133 g e dm
b. 4 b. 109 mL f. 2.86x103 cal
c. 7 c. 13 cm
d. 2 d. 14 g/mL
e f. 6
3 a. 1.0 e a. 145g e. 1.30x102dm
b f. 80 b. 64mL f. 16 cm
c. 6.2x c cm2 g. 6000cal
d d. 4.3g/cm3

9. Unit 1 Read pages 8-9 Unit 1 Sci. Notation and % Error
Chapter 1 Problems 20, 24, 26,30
Quiz: Oct 18/19 (Thursday / Friday)

10. Numbers and Measurement
Chemistry requires us to make accurate measurements that are often very small or very large.
To more easily handle these very large and small numbers, we use scientific notation.

11. Scientific Notation
Measurements are written as the product of two numbers
A coefficient – number between 1 and 10
10 raised to a power – the exponent indicates the number of times the coefficient must be multiplied or divided by 10.

12. Scientific Notation Write the following in scientific notation:
6,954,000
Write the following in standard numerical form:
6.75 x 10-3
1.865 x 102

13. Calculations in Scientific Notation
Multiplication
Multiply coefficients
Add exponents
Perform the following calculations:
7.2 x 102 · 5.02 x 10-3
1.0 x 102 · 2.6 x 108

14. Calculations in Scientific Notation
Division
Divide coefficients
Subtract the exponent of the denominator from the exponent of the numerator.
Perform the following calculations:
8.4 x 103 / 2.1 x 10-2
7.25 x 104 / 5.0 x 102

15. Calculations in Scientific Notation
Addition and subtraction
Make the exponent of both numbers the same
Align decimal points, and add coefficients
The exponent of the result will be the same as for the measurements

16. Calculations in Scientific Notation
Perform the following calculations:
6.3 x x 10-3
7.563 x x 10-3

17. Calculations in Scientific Notation
1.5 x x 103
6.38 x 10-3 – 3.8 x 10-4

18. International System of Units
Units of Measurement
Quantity
SI base unit or derived unit
Symbol
Length
meter m
Volume
cubic meter m3
Mass
kilogram kg
Density
grams per cubic centimeter
g/cm3
Temperature
Kelvin K
Time
second s
Pressure
Pascal Pa
Energy
joule J
Amount of Substance
mole
mol
Luminous Intensity
candela cd
Electric Current
ampere a

19. SI Units 103 for kilo- k 106 for mega- M 109 for giga- G
10-1 for deci- d
10-2 for centi- c
10-3 for milli- m
10-6 for micro- μ
10-9 for nano- n
10-12 for pico- p

20. Accuracy: Evaluations of Measurements
Accepted value: True or correct value based on reliable source
Experimental value: measured by you during the experiment

21. Error Difference between the accepted value and the experimental value
Take the absolute value

22. % Error % Error = Error / accepted value * 100
% Error = Actual – Experimental x 100
Actual

23. What is the % error?
A student measures a volume as 25.0mL, whereas the correct volume is 23.2mL.

24. Density Which is heavier – a pound of popcorn or a pound of cheese?
They would have the same mass!!
However, if you had equal VOLUMES of popcorn and cheese, the cheese would have more mass.

25. Density
A cube of gold-colored metal with a volume of 64 cm3 has a mass of 980. grams. The density of pure gold is 19.3 g/cm3. Is the metal pure gold?

26. Unit 1 HW: Read pages 9-10 Unit 1: Density and Temperature
More Conversion Problems

27. Temperature
The temperature of an object determines the flow of heat transfer.
Celsius scale uses the freezing point of water as 0 and the boiling point of water as 100.
Kelvin scale uses 273 for the freezing point of water, and 373 as the boiling point.

28. (Gabriel) Fahrenheit Scale
German physicist
Developed scale in 1714
Hg was used in thermometer
Freeze pt. water = 32˚F
Boiling pt. water = 212˚F
0˚F = freeze pt. of water, salt and dry ice (CO2)

29. Why use Hg in a thermometer?
For every degree the mercury’s temp. increases, the difference in which the Hg expands is NOTICABLE and CONSTANT.
Alcohol thermometer used in Alaska because Hg will freeze!

30. (Anders) Celsius Scale
Developed in 1742
Swedish Astronomer
Freezing pt. of water = 0˚C
Boiling pt. of water = 100˚C
Uses Hg in thermometer

31. (Lord William) Kelvin Scale
Developed in 1848
Based on absolute zero = zero heat energy = all motion stops
0 Kelvin = ˚C
No degree on scale (Kelvin units)
Kelvin is a theoretical scale because it does not compare the temp. to FP or BP of water.
Based on lowest temperature possible – No negative numbers on scale

32. Compare the 3 temperature scales