1. Introduction
Chemistry

2. Introduction
Safety Rules and Contract-see handout
Safety Contract and 30 lab hour letter must be returned,
signed by a parent/guardian by
Equipment-see handout
3. Precision vs. Accuracy
Metric System
5. Dimensional Analysis
Significant Figures
a. Addition and Subtraction
b. Multiplication and Division
% error-Table T
Density-Table T
Graphing

3. You are expected to follow all safety rules at ALL times whether
in the classroom area or in the laboratory area.
Before we begin any lab, you must have your apron and
safety goggles on.
Safety goggles and aprons are the LAST pieces of equipment that
we remove after a lab.
You must be completely cleaned up and ready to sit down before
they are removed.
You must be able to identify the safety equipment as noted in class.
You will take a safety lab quiz which you MUST get every question
correct. You will continue to take it until you answer all questions
correctly. Each additional time you take it, you will only be able
to score a 90, then an 80, then a 70 and so forth. Therefore, it is
to your advantage to get all answers correct the first time and score
a 100.

4. Two words which we use interchangeably are precision
and accuracy. Theoretically, they have very different meanings.
Precision-
Describes the closeness, or reproducibility, of a set
of measurements taken under the same conditions
Accuracy-
The closeness of a measurement to the true value of
what is being measured
See the duck handout in your packet

6. Four students perform experiments to determine the density of
sulfur. The accepted density of sulfur is 2.06 g/cm3. Which set
of data is precise and accurate?
precise but not accurate?
not precise but accurate?
neither precise nor accurate? IV I II
III
2.02
2.07
2.00
2.03
1.08
3.69
0.76
2.76
2.06
2.05
3.00
3.01
2.99
3.02
Neither
precise
nor
accurate
Precise
&
accurate
Precise but
not accurate
Not precise but
accurate

7. Metric System
Is an international system of measurement. The US is the only
industrialized country that is not officially using the metric system.
The other countries that do not use the metric are Liberia (W. Africa)
and Myanmar (SE Asia).
The nice thing about the metric system is that it is based on
the number 10 and therefore just requires moving the decimal point to make conversions.
Base Units
Mass-
Gram (g)
Length-
Meter (m)
Heat-
Joule (j)
Volume-
Liter (L)

8. Kilo
Hecto
Deka
Base
Deci
Centi
Milli
3400
34000
340000
3.4 34
340
If you are moving to the right, move the decimal pt. to the right
If you are moving to the left, move the decimal pt. to the left
.065
.65
6.5 65
650
6500
65000
.142
1.42
14.2
142
1420
14200
142000
.00029
.0029
.029
.29
2.9 29
1.75
17.5
175
1750
17500
175000

10. Move decimal pt. to the left, number gets smaller
Kilo
Hecto
Deka
Base
Deci
Centi
Milli 13
130
1300
13000
130000
0.0087
0.087
0.87
5.84
58.4
584
5840
58400
584000
811.89
8119.0
.81189
8.1189
81.189
2.692
26.92
2692
269.2
26920
269200
.74752
7.4752
74.752
747.52
7475.2
74752
Move decimal pt. to the left, number gets smaller
Move decimal pt. to the right, number gets larger

11. Dimensional Analysis aka Factor Label
A way to analyze and solve problems using the units or dimensions,
of the measurements.
Keep the conversion table in your packet in front of you. You will not have to memorize these conversions. For any test or quiz, you will have a clean copy of it in front of you!
It is a system of cancelling units of equivalent measures
6 inches  ? yards
6 inches
x 1 foot
12 in
x 1 yard
3 feet
6 inches
x 1 foot
12 in /
x 1 yard
3 feet /
= .17 yd / /

13. Significant Figures
The significant figures in a measurement include all of the digits
that are known, plus a last digit that is estimated
Measurements must always be reported to the correct number of
significant figures because calculated answers often depend on the
number of significant figures in the values in the calculation
To count the number of significant figures in a number, use the
Atlantic-Pacific Rule
If the decimal point is absent (Atlantic) start on the right side of the
number. Do not count until you reach the first non-zero digit. Once
you start counting, don’t stop until the number ends.
If the decimal point is present (Pacific) start on the left side of the
number. Do not count until you reach the first non-zero digit. Once
you start counting, don’t stop until the number ends.

14. Pacific
Ocean
Atlantic
Ocean
Decimal point absent
Decimal point present

15. 3000-
1 sf
5 sf
3000.-
4 sf
1 sf

16. Addition and Subtraction with sig. figs.
Answer should have the same number of DECIMAL PLACES as
the measurement with the least number of decimal places
Ex.:
349.0
2 decimal places
1 decimal place
2 decimal places
369.76
Answer can only have 1 decimal place
Answer:

17. Multiplication and Division of Sig. Figs.
Need to round the answer to the same number of significant figures
as the measurement with the least number of significant figures
Ex.: (2.10)(0.70)
= 1.47
3 sf
2 sf
Answer can only have 2 sig figs.
1.5

18. % Error
The equation can be found on Table T
The percent that a measured value differs from the accepted value
Measured (experimental) – accepted (true) x 100 =
accepted (true)
Jenn thought she received a 90 on her chemistry exam but
when the test was returned, she got an 85. What was her
percent error?
x = 85
5.88 %

20. On the same chemistry exam, Sal thought he got a 74 but when the test was returned, he got a 89. What was his percent error?
74 – 89 x 100 = 89 %
What does a “+” percent error mean?
The measured value is greater than the accepted value
What does a “–” percent error mean?
The measured value is less than the accepted value

21. Density
The ratio of the mass of an object to its volume
Formula is on Table T
Density = mass
volume
Mass is obtained through use of the electronic balance
Volume is obtained 1 of 2 ways
1. Direct measurement (L x W x H)-look for units cm3
2. Water Displacement (final vol – initial vol)-look for units mL

23. Volume of an irregular shaped object through water displacement
1. Find the mass of the irregular shaped object
2. Fill a graduated cylinder with water and record the volume
3. Carefully put the object into the graduate
4. Record the volume of the water with the object in the graduate
Subtract the final vol (step # 4) from the initial vol (step # 2)
This is the volume of the irregular shaped object
Why is it important to mass the object before finding its volume?
The water from finding its volume will add mass to the object

24. Properties used to describe matter are both intensive and extensive
Extensive property-
A property that depends on the amount of
matter in the sample
Intensive property-
A property that does not depend on the amount
of matter in the sample

25. What are some intensive & extensive properties?
odor
mass
density
volume
boiling point
length
color
weight
melting point
texture
conductivity
luster
ductility
malleability
hardness

26. Graphing
Rules for graphs
1. All graphs are done on a full sheet of paper
2. Never use the back of the graph paper
3. Graphs are always done in pencil
4. Draw each axis with a ruler
5. Label each axis and include units if necessary
If more than one piece of information is being graphed on the
same graph, include a key
7. The spacing on each axis must be consistent
8. Each graph must have a title

27. What information goes on the x-axis?
What information goes on the y-axis?
Independent variable-the variable that is changed during an
experiment. AKA manipulated variable
Dependent variable-the variable that is observed during an
experiment. AKA responding variable
The independent variable ALWAYS is on the x-axis
The dependent variable ALWAYS is on the y-axis.

28. In science, most numbers that are reported need units
It is not enough to report a number as 54
Did you mean 54 g?
54 mg?
Most numbers need units to ensure that all work is
accurate
Look at what an error can lead to