CHM1
Review for Exam 2
The following are topics and sample questions for the second exam.
Topics
1. Scientific Method
a. Observation
b. Hypothesis
c. Experiment
d. Theory
e. Laws
2. Scientific Notation
3. Metric System and SI units
a. Prefixes
b. Unit conversions
4. Measurement
5. Significant Figures
a. Multiplication/Division Rules
b. Addition and subtraction Rules
6. Matter,
a. Pure substance,
i. Elements
ii. Compounds
b. mixtures,
i. homogeneous
ii. heterogeneous
c. The number of atoms in Chemical Formulas
d. Chemical Recations
7. Dimensional Analysis
8. Density, D = m/V
Multiple Choice Questions
1. Which is a mixture of
substances?
(1) air
(2) water
(3) copper
(4) helium
2. How many milliliters are in one
liter?
(1) 10-3
(2) 103
(3) 10
(4) 0.01
3. Which of these contains only one
substance?
(1) distilled water (3) salt water
(2) sugar water (4) rain water
4. How many oxygen atoms are in
the formula Ca3(PO4)2
(1) 3
(2) 8
(3) 4
(4) 12
CHM1
Review for Exam 2
5. The diagram below represents a
portion of a 100 milliliter
graduated cylinder.
7. Which type of matter is
composed of two or more
different elements that are
chemically combined in definite
ratios?
(1) a solution
(2) a compound
(3) a homogeneous mixture
(4) a heterogeneous mixture
8. Two basic properties of the gas
phase are
What is the reading of the meniscus?
(1) 35 mL
(2) 35.0 mL
(3) 45 mL
(4) 45.0 mL
6. Which diagram represents a
mixture of monoatomic
elements?
(1) a definite shape and a definite
volume.
(2) a definite shape but no definite
volume.
(3) no definite shape and a definite
volume.
(4) no definite shape and no definite
volume.
9. For the following chemical reaction
which of the following is a product?
2 H2 (g) + O2 (g)  2 H2O (g)
(1) H2 (g)
(2) 2 H2 (g)
(3) O2 (g)
(4) H2O (g)
(1)
(3)
10. How many significant figures are
in 0.250?
(1) 1
(2) 2
(2)
(4)
(3) 3
(4) 4
11. Which sample of matter is a
solid?
(1) H2O (l)
(2) H2O (g)
(3) NaCl (s)
(4) NaCl (aq)
CHM1
Review for Exam 2
Short Answer Questions
Base your answers to the following questions on the particle diagrams below, which
show atoms and/or molecules in three different samples of matter at STP.
12. Which sample represents a pure substance?
13. Explain why
does not represent a compound?
14. What are the products of the combustion of methane (CH4)?
15. What is the volume of an object that has a mass of 25.0 g and a density of 3.4
g/mL. You must show work and report your answer with the proper number of
sig figs.
CHM1
Review for Exam 2
16. Give the answer with the proper number of significant figures
a. 6.500 x 0.0450 =
b. 7.1 + 5.5000 =
c. (3.56 + 2)/5.0 =
17. Provide the following in scientific notation with the proper number of significant
digits.
a. 0.00276
b. 2000
c. 90.1
18. Using dimensional analysis, calculate how many seconds are in 2.0 centuries.
19. Using dimensional analysis, how far will a car travel in 120 seconds, if the car’s
speed is 65 km/hr.
CHM1
Review for Exam 2
Matching
20. _____ 10 cm
a. 106 m
21. _____ 1000 mm
b. 1 m
22. _____ 1 km
c. alloy
23. _____ 1 Mm
d. eight hydrogens
24. _____ Brass
e. energy
25. _____ (NH4)2CO3
f. 0.10 m
26. _____ Joules
g. compound
27. _____ O2
h. element
28. _____ CO2
i. homogeneous mixture
29. _____ soil
j. heterogeneous mixture
30. _____ air
k. 1000 m
True/False (you must write true or false in the blank)
31. __________ The prefix milli- means 103.
32. __________ 0.0120 has three significant figures.
33. __________ White sugar is a pure compound.
34. __________ Water melting is a chemical reaction.
35. __________ 1000 mL is the same as 1 L.
36. __________ 0.001 m is the same as 1 mm.
37. __________ Water is an element.
38. __________ Heat is a form of energy.
39. __________ A solid has a fixed shape and volume.
40. __________ Melting in a process in which a liquid become a solid.
CHM1
Review for Exam 2
Reading for Comprehension
Fever Thermometers
Dennis_Loney
Your doctor or parent may bust out an electronic oral or ear thermometer when you’re
sick (or pretend to be sick), but when I was growing up, we had old-fashioned mercury
fever thermometers to gauge our internal body temperature.
The government is trying to phase out fever thermometers that contain mercury—a
silvery-white metal—because it is a toxic substance that can harm both humans and
wildlife. If mercury thermometers break, the mercury can evaporate into the air if it’s not
properly cleaned up. Today, many new fever thermometers contain an alcohol that is
dyed red or blue. They are just as accurate in measuring your temperature as mercury
filled thermometers, but how do they work?
Mercury and alcohol fever thermometers work in the same way. That is because all
objects expand when they are heated and contract when they are cooled. With most
objects, you can’t tell this is taking place with your naked eye. With fever thermometers,
you can see the liquid increase in volume as the temperature rises and fall when it cools.
This is because the liquid is inside a really narrow space.
When the thermometer is placed under your tongue, the warmth of your body heats the
smooth metal tip on the end of the thermometer. This metal tip transfers your body heat
to the liquid inside the glass tube. The molecules of the liquid start to get excited and
bounce around. (Think of a super ball. The harder you bounce it—that is, the more
energy you exert on the super ball—the higher in the sky it will bounce.) As the
temperature rises, the molecules need more space, so they stretch out. This is what makes
the liquid inside the thermometer rise.
CHM1
Review for Exam 2
41. What phase of matter is mercury at room temperature?
42. What phase change occurs when a substance evaporates?
43. Why are mercury thermometers being phased out of use?
44. What happens to the volume of the liquid in a thermometer as the temperature
increases?
45. What happens to the density of the liquid as the temperature increases?
46. What happens to the space between atoms or molecules as the temperature
increases?
47. What type of lab equipment is shown in the picture? Hint, they are not
thermometers.
CHM1
Review for Exam 2
Answers
1. 1
2. 2
3. 1
4. 2
5. 2
6. 3
7. 2
8. 4
9. 4
10. 3
11. 3
12. 3
13. Both circles represent the same
type of atoms, so it is an element,
whereas a compound must have
two or more different types of
atoms.
14. Water, carbon dioxide and heat.
15. 7.4 mL
16. (a) 0.293; (b) 12.6; (c) 1
17. (a) 2.76 x 10-3; (b) 2 x 103; 9.01 x
101
18. 6.3 x 109s (this answer would
not receive full credit without
showing the dimensional
analysis)
19. 2.1 km (this answer would not
receive full credit without
showing the dimensional
analysis)
20. f
21. b
22. k
23. a
24. c
25. d
26. e
27. h
28. g
29. j
30. i
31. false
32. true
33. true
34. false
35. true
36. true
37. false
38. true
39. true
40. false
41. Liquid
42. Liquid to gas
43. Mercury is toxic
44. The volume increases.
45. The density decreases.
46. The space between molecules
increases
47. pipets