1. CHEMISTRY Physical Chemistry Environmental Chemistry Nanotechnology
Organic Chemistry
Chemical
Engineering
Biochemistry
Inorganic Chemistry

3. Measurement Metric system (National Assembly of France, 1790)
International System of Units (SI, 1960)
Derived units: combinations of fundamental units
Ex. Speed (m/s)

4. Equipment for Measurement
Length
Volume
Mass
Time
Temp

5. Scientific Notation Width of a human hair = 0.000008 m Coefficient
Power of Ten: 10x
Coefficient? 8
Power?
10-6
8 x 10-6 m

6. How many atoms of water are in a Lake Washington?
Scientific Notation
How many atoms of water are in a Lake Washington?
97,000,000,000,000,000,000,000, 000,000,000,000,000 atoms
-or-
9.7 x atoms

7. Scientific Notation on Calculators
Your calculator should work with scientific notation! Look for: EE
EXP
Note:
9.64 x 105 = E5
Coefficient
Power of Ten
2. x = 2.E-8

8. Scientific Notation Conversion to a standard number 3.252 x 106
If power of ten is positive,
move decimal point to the RIGHT
(add zeros if necessary)
4.56 x 10-3
If power of ten is negative,
move decimal point to the LEFT
(add zeros if necessary)

9. Measured Numbers Numbers obtained when you measure a quantity
Estimate the final digit 1 2 6 5 4 3
4.8 in
Read greater than 4 and less than 5; estimate last digit 1 2 6 5 4 3
4.84 in
Read greater than 4.8 and less than 4.9; estimate last digit

10. Significant Figures All measured digits, including the estimated digit
4.84 cm
2045 g
2.333 x 10-5 L
50. s
Zeros not significant in 2 situations:
At the beginning of a decimal number
At the end of a number without decimal point
4500 cm kg L

11. Exact Numbers A counted number (not measured!)
Ex. # of students in this classroom
A definition comparing two units in same measurement system
Ex. 1 ft = 12 in
Ex. 1 kg = 1000 g
NOT considered as significant figures!

12. Significant Figures in Calculations
In lab, at work, we measure things. Then what?
The number of sig figs in measured numbers limits the number of sig figs in a calculated answer.
You can’t have more detail in your answer than
you have in your measurements
Number of sig figs in answer depends on what type of calculations you performed

13. Sig Figs in Calculations
Multiplication and Division:
Final answer has the same number of sig figs as the measurement with the fewest significant figures
Addition and Subtraction:
Final answer has the same number of decimal places as the measurement with the fewest decimal places
x =
79. =
-1.7
= 10
10.000

14. Rounding Rules
How do we limit the number of sig figs? Rounding! Look at first non-significant number (to be dropped) Is this number 4 or less? Is this number 5 or more?
Round “down”
Round “up”
to 4 sig figs
2390.
to 2 sig fig
0.0056
to 3 sig figs
689000

15. Prefixes
Is it easier to write:
g or 590 kg?
g or 0.4 mg?
Prefixes can be attached to units to increase or decrease size by a factor of 10
(multiply by 10 or divide by 10)
Multiply by 10x
Multiply by 10-x

16. Common Prefixes with SI Units

17. Equalities used in Measurements
Equality:
A relationship between two units that measure the same quantity
Length:
1 m = 100 cm = 1000 mm
Volume:
1 L = 10 dL = 1000 mL
1 dL = 100 mL
Cubic centimeter: cc
1 cm x 1 cm x 1 cm = 1 cm3
1 cc = 1 cm3 = 1 mL

18. Volume Conversions 1 m3 = 1000 L
If 1 cubic centimeter equals 1 mL, how many milliliters does 1 cubic meter equal?
1 m = 100 cm
100 cm x cm x cm = cm3
cm3 = mL
1 x 106 mL
1 m3 = 1000 L
1 x 103 L

19. Conversion Factors: Changing Between Units
1 hr = 60 min
Conversion Factor:
Metric Conversion Factor:

20. More Conversion Factors
Metric Conversion Factors:
Metric- U.S. System Conversion Factors:
1 kg = 2.20 lb
1 km = mi

21. More Conversion Factors
Standard equalities can be looked up in a table (Table 1.9 in your book, for example)
Other equalities may be stated in a problem
Examples:
The average speed of cars driving on I-5 during rush hour is 11 mph.
Equality: 11 miles = 1 hour
One five pound bag of sugar costs $4.00.
Equality: 1 bag = 5 lb = $4.00

22. Percents as Conversion Factors
Percent means 1 per 100
Example:
If a person is 20% body fat by mass, then:
20 kg fat = 100 kg body total

23. End of class Practice Questions
How many sig figs are in each the following? L
53,069 s m
0.509 kg
Write the numbers above in scientific notation.
How many sig figs does each have now?
Write a conversion factor relating micrograms to grams

24. Practice Questions
What is the temperature on each (˚C) thermometer shown? (sig figs!)
4.9 ˚C
61.5 ˚C
Is each of the following an exact or measured number?
The number of chair legs in this room
The length of your benchtop in inches
The length of your benchtop in cm
The area of the projector screen
Exact
Measured
Measured
Measured

25. Using Conversion Factors
Your patient tells you that she recently lost 15 kg.
How many pounds has she lost?
What’s given? What do we want to know?
What conversion factors do I need?
Set up problem
weight lost (kg)= 15 kg
weight lost (lb)= ? lb
kg  lb
2.20 lb = 1 kg

26. Using Conversion Factors
kg  lb
3. Set up problem
15 kg x ?
Check
sig figs!

27. Using Conversion Factors
The recommended daily value of vitamin C is 60 mg. If an average orange contains 45 mg of vitamin C, how many oranges should you eat in a week?
What’s given? What do we want to know?
What conversion factors do I need?
1 week
# of oranges
week  # oranges
 days
 mg vitamin C

28. Physical Properties of Materials
Physical Property:
can be measured or perceived without changing the material’s identity
Intensive
Independent of amount of substance
Ex. Boiling point
Extensive
Depends on amount of substance
Ex. Mass, volume

29. Density Relationship between mass and volume
Density is a physical property
Density is an intensive property
4 times more mass
4 times more volume

30. Density Units: Density of water (at 20˚C and typical room pressure)
SI: kg/m3
often use: g/L
g/mL
g/cm3
g/cc
Density of water (at 20˚C and typical room pressure)
1 g/cc 1 g/mL

31. Density of Solids How can we determine the density of a solid?
Need to know mass
Need to know volume
Measure displacement
of water
Does this method work for all solid materials?

32. Density Table
Density can be used as a conversion factor! (relates mass to volume)

33. Specific Gravity (sp gr)
Ratio between density of substance & density of water
Measure sp gr with a hydrometer
Units for sp gr?
Unitless!

34. Temperature
Measure of how hot or cold a substance is relative to another substance
Scales and Units
Scale
Boiling Point H2O
Freezing Point H2O
Celsius ˚C
Fahrenheit ˚F
Kelvin K
100˚C
0˚C
212˚F
32˚F K K
Note: the unit is not ˚K

35. Temperature Conversions
How many units are between boiling point and freezing point of water?
Scale
Celsius ˚C
Fahrenheit ˚F
Kelvin K
100˚C – 0˚C
= 100 units
212˚F – 32˚F
= 180 units
373 K –273 K
= 100 units
the unit 1 Kelvin equals the unit 1 degree Celsius

36. Converting Units Fahrenheit to Units Celsius
180 Fahrenheit degrees = 100 Celsius degrees

37. Things to Remember about the Temperature Scales
0 K is absolute zero
You can never (ever ever ever) have a temperature of negative K
The unit for the Celsius scale is the degree C (˚C)
The unit for the Fahrenheit scale is the degree F (˚F)
The units for the Kelvin scale is the Kelvin (K)
A change of x Kelvin = a change of x ˚C
Start value and end values are different;
Both changed the same amount (50 K units = 50 ˚C units)

38. Precision and Accuracy
Precision: reproducibility
Accuracy: how close to actual value
Temp (˚C)