Data Analysis in Chemistry
Quantitative v. Qualitative
Measurements
Standard Measurements
--SI System (Système Internationale d’Unités
SI Base Units
Length
Mass
Time
Temperature
meter (m)
kilogram (kg)
second (s)
Kelvin (K)
Amount of Substance
Luminous Intensity
Current
mole (mol)
candela (cd)
Ampere (A)
The above units are considered to be base units.
Things that are smaller than the base units use
Latin prefixes; things that are larger use Greek
prefixes.
Prefixes in the SI System
gigamegakilodecicentimillimicronanopico-
G
M
k
d
c
m

n
p
1000000000
1,000,000
1000
0.1
0.01
0.001
0.000001
0.000000001
0.000000000001
109
106
103
10-1
10-2
10-3
10-6
10-9
10-12
Scientific Notation Review:
Very large and very small numbers should be
expressed in scientific notation.
65000000 m becomes 6.5 x 107 m
0.000045 g
becomes 4.5 x 10-5 g
When using your calculator use the “EE” key
that appears above the comma.
Use conversions factors to solve the
following:
345 mm =_____ m
678 kg = _____ g
Significant Figures





Include all known digits plus one
estimate digit.
All non-zero numbers are significant.
Captive zeros are significant.
Trailing zeros are only significant when
there is a decimal point.
Trailing zeros are NOT significant when
there is no decimal point.
Atlantic - the "A" stands for
decimal absent. This means
that they start on the atlantic
ocean side of the number, find
the first non-zero number and
count everything after.
Pacific - "P" stands for
decimal present. Start on the
pacific side of the number at
the first non-zero number and
then count everything after.
http://science.widener.edu/svb/tutorial/sigfigures.html
Derived Units
A derived unit is one that is a combination of base units.
Examples are volume (the space occupied by an object)
1 mL = 1 cm3
1 L = 1 dm3
and density (the ratio of the mass to the volume of an
object)
D = mass
volume
Accuracy and Precision
Accuracy refers to how close a value is to the accepted
value.
Precision refers to how close measurements are to each
other.
Percent Error is used to determine the accuracy of your
experimental results. Use the following formula to
calculate percent error:
Percent Error = Experimental – Accepted Value x 100
Accepted Value
Determine the percent error when a student calculates
the density of copper to be 7.65 g/cm3. The true value
for the density of copper is 8.92 g/cm3.