1. Measurement Used in everyday life: cooking, taking your temperature
Also used extensively in chemistry: mass, volume, etc.
Gives you a way to make quantitative observations about the world around you

2. Observations Qualitative = What is it? Quantitative = How much?
Quantitative observations (measurements) always include a Number plus a Unit
- 4 inches
- 1 pound

3. Units of Measurement US system, metric and SI
Metric is most common in science and medicine
Know US and Metric units for:
- Length (feet, meters)
- Volume (quarts, liters)
- Mass (pounds, grams)
-Temperature (Fahrenheit, Celsius)

4. Measuring Length
When making measurements, estimate one digit farther than the finest markings

5. Measuring Volume
When measuring volume, always read at the bottom of the meniscus
Remember to estimate one digit farther than the finest markings

6. Measuring Mass
When measuring mass, record all of the digits provided by the scale

7. Measuring Temperature
Again, remember to estimate one digit more than the finest markings on the thermometer

8. Metric Prefixes Use a prefix to relate a unit to its base unit
Base unit for length is the meter, and kilo = 1000, so 1 kilometer = 1000 meters
Know metric prefixes and abbreviations for metric units ( 1 kilometer = 1 km)
Use the correct abbreviations for units so that you don’t mix them up

9. Scientific Notation
Scientific notation is used to write large or small numbers
1000 = 1 x 103
0.001 = 1 x 10-3
Scientific notation has a coefficient times a power of 10, where the coefficient is a number from 1 to less than 10
Learn to use scientific notation on your calculator

10. Measured and Exact Numbers
When measuring, the last digit is estimated by reading between the smallest divisions
Therefore, measured numbers have uncertainty
Exact numbers have no uncertainty
Exact numbers come from counting whole objects, or from definitions:
- There are 33 people in this room
- 100 cm = 1 m

11. Accuracy vs. Precision Accuracy = How close to the true value?
Precision = How repeatable is the measured value?

12. Significant Figures
All reported digits in measured numbers are significant (including the estimated one)
Sig. Figs. are a measure of uncertainty
More sig. figs. = less uncertainty
For numbers ending in zero, it’s best to use scientific notation to indicate sig. figs.:
500 = 5 x 102 vs = 5.00 x 102

14. Sig. Figs. in Measurements

15. Sig. Figs. In Calculations
For adding and subtracting: line up decimal places and use fewest decimal places in answer
= on calculator
Correct sig. figs. = 12.4
For multiplying and dividing: use least sig. figs. in answer
2.3 x 1.11 = on calculator
Correct sig. figs. = 2.6
Always carry all decimal places through multi-step calculations and then adjust sig. figs. at end

16. Unit Conversions
To convert from one unit to another, a conversion factor is used
The conversion factor comes from an equality
Example: 1 kg = 1000 g can become
1 kg/1000 g or g/1 kg

17. Solving Unit Conversion Problems
State given information
State unit plan
State equality and conversion factors
Set up calculation
Cancel units and calculate answer
Correct sig. figs.

18. Example Unit Conversion Problem
A marathon is 26.2 miles long. How long is it in kilometers?
Marathon = 26.2 miles
mi  km
1 km = mi so, 1 km/0.621 mi
26.2 mi x 1 km/0.621 mi = km
26.2 mi x 1 km/0.621 mi = km
Correct sig. figs. = 42.2 km

19. Temperature Conversions
Three temperature scales are Fahrenheit, Celsius and Kelvin
F = 1.8C + 32
C = F - 32(0.555)
K = C
For example:
Dry ice at -56.5C is at -69.7F and is at K

21. Percent Calculations % = (part/whole) x 100%
Percent can be used as a conversion factor
20% can be 20/100 or 100/20
Example:
If wine is 13% alcohol (by volume), how many mL of alcohol are in 125 mL of wine?
(125 mL wine) x (13 mL alcohol/100 mL wine) = 16 mL alcohol

22. Density
Density is a measure of how much mass there is per volume: d = m/V
Helium is less dense than air, so a helium balloon floats
Copper and zinc are more dense than water, so a penny sinks in the wishing well
Density can be in any units of mass/volume (g/mL, g/L, kg/L etc.)

23. Densities of Some Common Substances

24. Indiana Jones Movie Example
In the movie, Jones replaces a gold statue with sand in order to avoid setting off a deadly booby trap
The density of gold = kg/L and the density of sand = about 3 kg/L
If the same volume of sand is used to replace the statue, will the booby trap be set off?
Yes, gold is around 7 times as dense as sand, so you would have to use around 7 times the volume
If the volume of the idol is 1.0 L (the idol is solid gold), what is its mass (in kg and in lb)? (1 kg = 2.20 lb)
m = dV = (19.32 kg/L) x (1.0 L) = 19 kg
19 kg x 2.20 lb/1 kg = 43 lb

25. Density from Water Displacement Method
When fully submerged, a solid object will displace its volume in water
Volume of the water is measured before and after submerging the object
- the volume difference = the volume of the object
- the mass is measured and d = m/V