General Chemistry
Unit 1 Review
Name: ANSWER KEY
Physical and chemical properties and change:
Give three examples of physical properties that can be easily observed.
1. Color
2. size/shape
3. mass
Give three examples of chemical properties that can be easily observed.
1. flammability
2. reactivity to oxygen
3. reactivity to water
Identify each of the following as either a physical change or a chemical change.
Change
Physical or Chemical
1. Salt dissolves in water.
P
2. Ammonia evaporates.
P
3. Old hydrogen peroxide is no longer effective because it has broken
C
down into water and oxygen.
4. Dry ice (solid CO2) sublimates (changes to vapor) to make “stage fog”.
P
5. A green leaf turns red in the fall.
C
6. Yellow food coloring is put into water.
P
Classification of matter:
Classify each as a homogeneous mixture, a heterogeneous mixture, an element or a compound. Also indicate
which lab technique(s) could be used to separate the mixtures.
Lab Techniques include distillation, evaporation, chromatography, and filtration.
Matter
Classification
Possible separation techniques
(mixtures only)
Water and alcohol (alcohol’s BP = 195oC)
Homogen. mix.
Evaporation or distillation
Gatorade
Homogen. mix.
evaporation
Sugar water
Homogen. mix.
evaporation
a quartz crystal (SiO2)
compound
--gold (Au)
element
--the gas inside a helium balloon (He)
element
--butane (C4H10)
compound
--artificial vanilla
Homogen. mix.
distillation
sterling silver (Ag 90%, Cu 10%)
Homogen. mix.
X None of the above
Complete the following equalities/facts using your knowledge of the metric system:
1g=
1000
mg
1000 mL =
1
100 cm =
1
m
1000 g =
1
kg
1000 L =
1
kL
1 cm =
10
mm
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L
Complete the following metric conversions using factor labeling (show work and include ALL units):
5.00 g =
.00500 kg
165 cm =
1650
mm
.560 L =
560.
mL
675,000 mL = .675
kL
550 mg =
.55
g
0.75 m =
75
cm
Use factor labeling to solve the following word problem:
Mr. Ko plans to do an experiment with his IB Chemistry classes that requires 3 test tubes per student (3 test
tubes = 1 student). How many dozens of test tubes will Mr. Ko need to supply to the students in his two classes
if each class has 32 students (1 class = 32 students)?
2 classes | 30 students | 3 test tubes | 1 dozen
= 16 doz
| 1 class
| 1 student | 12 test tubes
Mars is an average of 141 million miles from earth. How long would it take for a laser beam from the Earth to
reach Mars? (speed of light is 3.00 x 1010 cm/sec) (1 mile = 1.609 km)
141,000,000 mi | 1.609 Km | 1000 m | 100 cm |
1 sec
= 756.23 sec 756 sec or 12.6 min
| 1 mi
| 1 Km
|
1m
| 3.00 x 1010 cm
Describe each scenario in terms of both precision and accuracy:
A basketball player attempts five shots and hits the front of the rim each time. Good prec/poor accuracy
A basketball player attempts five shots and makes it each time. SWISH! Good precision/good accuracy
A basketball player attempts five shots. He hits the rim three times and makes it twice. poor prec/poor accur
A basketball player attempts one shot and makes it. Good accuracy, precision cannot be evaluated
Experimental Design:
 A chemistry student is interested in testing the effects of acid rain on tomato plant growth. She changes
the pH of her watering solution and measures the height of the tomato plants as they grow. Identify her
manipulated and responding variables and list at least five possible variables that would need to remain
constant. pH = manipulated variable and height = responding variable
pH on the x-axis and height on the y-axis-----a line graph would be best
controlled variables: amount of water and light, soil, fertilizer, container size, temperature, variety of plant…
Percent Error and Uncertainty:
 A student measures using an electronic balance the mass of a samples of salt as 43.21 g +/- .02 g. How many
significant figures are in this measurement? What is the uncertain digit? What factor affects the
certainty of this measurement? 4 sig figs;
“1” is the uncertain digit:
a) skill of the student
b) quality of the balance,
precision of the balance

The theoretical mass of the above sample of salt is found to be 45.00 g. Determine the percent error in the
student’s measurement. (43.21g – 45.00g) x 100 = -3.9777% or -3.98% (close enough for % problems)
45.00 g
(technically, its: -3.978%)
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