1. Measurement

2. A quantity that has both a number and a unit
Measurement
A quantity that has both a number and a unit

3. The metric system: SI Units
Base units
Prefixes
Prefix
Symbol
Meaning
Factor
kilo— k
1000 times larger
103
centi— c
100 times smaller
10−2
milli— m
1000 times smaller
10−3
micro— μ
1 million times smaller
10−6
nano— n
1 billions times smaller
10−9
Base Quantity
Unit
Symbol
Length
meter m
Mass
kilogram kg
Time
second s
Temperature
kelvin K
Amount of Substance
mole
mol

4. Temperature
K = °C + 273

5. Measuring with a Ruler Measuring error = 1/10 of smallest division
Reading error is equal to 1/10 of the smallest division on the ruler

6. Practice 1. 2.

7. Measure from the bottom of the meniscus
Measuring a Liquid
Measure from the bottom of the meniscus

8. Beaker
Erlenmeyer Flask

9. Practice 2. 1.

10. 4. 3.

11. Accuracy vs Precision
How close a measurement comes to the actual value of whatever is measured
The more # of significant digits, the more accurate the value
How close a series of measurements are to one another or “repeatability”
You must compare two or more measurements to each other

13. Jack has a height of 70 inches. Which sets of measurements are
Example
Jack has a height of 70 inches. Which sets of measurements are
Accurate and precise
Precise but not accurate
Neither precise nor accurate
69.5 in., 70.5 in., 70.1 in.
45.3 in., 62.1 in., 84.3 in
78.3 in., 78.0 in., 78.1 in

14. To find out how close you are to an accepted or actual value
Percent error
To find out how close you are to an accepted or actual value
Percent error =  exp val – act val  x 100%
act val
error
Example: Your data reads 99.1g but the accepted value is 101.0g, what is your percent error?