AP Chemistry
Unit 4 Review
1.
Fill in the table. The first gas law has already been completed.
Gas Law
Boyle’s Law
Statement/mathematical relationship
Volume of a fixed quantity of gas at constant temperature is
inversely proportional to the pressure.
What is constant
n, T
Equation
P1V1 = P2V2
Charles’ Law
Gay-Lussac’s Law
Avogadro’s Law
Ideal gas Law
Dalton’s Law
2.
Compare H2 (2 g/mol) to O2 (32 g/mol).
How many times more kinetic energy at 400 K? __________
How many times faster at 400 K? __________
How many times faster diffusion rate at 400 K? _________
3.
T is doubled at constant P, how are the following affected?
a) volume_________, kinetic energy_________, density_________, velocity_________,
P is doubled at constant T: how are the following affected?
b) volume_________, kinetic energy_________, density_________, velocity_________,
4.
A 248.0 mL gas sample has a mass of 0.433 g at a pressure of 745 mmHg and a temperature of 28°C. What is the molar
mass of the gas?
5.
What is the density of hydrogen gas (g/L) at 20.0°C and a pressure of 1655 psi?
6.
What is the average speed of a carbon dioxide gas molecule at a temperature of 25C.
7.
Convert each of the following pressures below to atm:
a) At the peak of Mt. Everest, atmospheric pressure is only 2.75 x 102 mmHg
b) A cyclist fills her tires to 86 psi.
c)
The surface of Venus has an atmospheric pressure of 9.15 x 106Pa.
d) At 100 ft. below sea level, a scuba diver experiences a pressure of 2.54 x 10 4 torr.
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8.
Potassium chlorate was heated in a test tube and decomposed. The oxygen produced was collected by water displacement
at 22°C at a total pressure of 754 mmHg. The volume of gas collected was 0.650 L. Calculate the partial pressure of O 2 in
the gas collected.
9.
3.0 L of argon and 2.0 L of helium both at a temperature of 25°C and 770 mmHg are pumped into a 1.0 L steel container.
What is the partial pressure of each gas in the container at a temperature of 25°C?
10. Ammonium nitrate is a common ingredient in chemical fertilizers. Use the reaction shown to calculate the mass of solid
ammonium nitrate that must be used to obtain .10 L of dinitrogen monoxide gas at STP.
NH4NO3(s)  N2O(g) + 2H2O(g)
11. Equal masses (0.500 g each) of hydrogen and oxygen are placed in an evacuated 4.00 L flask at 25°C. The mixture is allowed
to react to completion and the flask is returned to 25°C and allowed to come to equilibrium. The equilibrium vapor
pressure of water at 25°C is 23.76 torr.
a) Write and balance a chemical equation for the reaction.
b) What is the total pressure inside the flask before the reaction begins?
c)
What is the mass of water vapor in the flask at equilibrium?
d) What is the total pressure inside the flask at equilibrium?
1.
A 3.00 L flask at 25°C contains 5.00 g each of He(g), HCl (g) and H2O(g). Answer the following and explain your reasoning:
a) Which gas has particles with the highest average kinetic energy?
b) Which gas has particles with the highest average velocity?
c)
Which gas has the highest partial pressure?
d) Which gas will deviate most from ideal behavior?
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e)
Which substance will have the highest boiling point?
f)
What changes in temperature and pressure will increase the deviations of all the gases from ideal behavior?
12. Each glass sphere contains a gas at the pressure and volume shown and the temperature is 25°C. Determine the partial
pressure of each gas after the valve is opened and they are allowed to mix.
13. A 100.3 mL sample of carbon dioxide is collected over water at 25.0°C and 775 mmHg pressure. What is the volume of the
dry gas at STP?
14. Fill in the blank boxes with the correct name or formula.
(NH4)3PO4
sodium dichromate
Ag2SO4
perchloric acid
MnSO3
dinitrogen trisulfide
HC2H3O2(aq)
copper(I) oxalate
Ni(OH)2
aluminum dichromate
15. The graph shows the distribution of molecular velocities for the same molecule at
two different temperatures (T1 an T2). Which temperature is greater?
Explain, include an equation in your explanation.
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16. When a thin glass tube is put into water, the water rises 1.4 cm. When the same tube is put into hexane (C6H14), the hexane
rises only 0.4 cm. Explain.
17. In each pair of compounds, pick the one with the higher vapor pressure at a given temperature. Explain your reasoning.
a) Br2 or I2
_____________________________________________________________________________
b) H2S or H2O
_____________________________________________________________________________
c)
_____________________________________________________________________________
NH3 or PH3
18. (a) Draw the lewis structures. (b) Identify the intermolecular forces of attraction and (c) arrange the substances in order of
increasing boiling point: CH3CH3, CH3OH and CH3CH2OH.
19. Consider the heating curve
for water for the following
questions:
a) For section D-E
what is the
absorbed energy
doing to the water
molecules?
b) For section B-C
what is the
absorbed energy
doing to the water
molecules?
label the graph the following phase changes and include the ∆𝐻 value for each: vaporization, condensation,
solidification, fusion.
d) How much energy is released if 5.0 g of water vapor at a temperature of 120°C are cooled to a final temperature of
-25°C?
c)
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20. How much energy does a 100.0 g chunk of ice at an initial temperature of -90°C absorb if it’s heated to a final temperature
of -5.0°C?
21. Identify the strongest intermolecular force operating in the condensed phases of the following substances. Explain how you
determined this.
a. Cl2
b. CO
c. SO2
d. CH2Cl2
e. HF
g. CH3-O-CH3
22. Can the circled two atoms hydrogen bond? Why or why not?
a)
b)
c)
d)
23. True or false, if false, rewrite the sentence so it is true.
a) Hydrogen bonding can occur within a molecule that has hydrogen bonded to nitrogen, oxygen, or fluorine.
b) Hydrogen bonding can occur between the nucleus of an oxygen atom and a lone pair of a hydrogen atom
c)
Hydrogen bonding is a stronger force than an ionic bond
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24. Draw a correct representation of hydrogen bonding between the following molecules. Write “no hydrogen bonding” if
hydrogen bonding cannot occur between the molecules.
a)
c)
e)
g)
i)
b)
d)
f)
h)
j)
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25. Upon swabbing on the back of your hand, which substance would create the most cooling effect at room temperature?
Explain your answer. (a) methanol CH3OH (b) ethanol CH3CH2OH (c) 1-propanol CH3CH2CH2OH.
26. Use Coulomb’s law to qualitatively explain two reasons why hydrogen bonds, which are especially strong dipole-dipole
forces of attraction, form only between hydrogen on one molecule and either N, O, or F on another.
27. The boiling points, surface tensions, and viscosities of water and several alcohols are as follows:
water, H2O
ethanol, CH3CH2OH
propanol, CH3CH2CH2OH
n-butanol, CH3CH2CH2CH2OH
ethylene glycol, HOCH2CH2OH
a)
Boiling point
(℃)
surface tension
(J/m2)
viscosity
(kg/m∙s)
100
78
97
117
197
.073
.023
.024
.026
.048
0.9 x 10-3
1.1 x 10-3
2.2 x 10-3
2.6 x 10-3
4.8 x 10-3
For ethanol, propanol and n-butanol the B.P., surface tensions and viscosities all increase. Explain/justify.
b) How do you explain the fact that propanol and ethylene glycol have similar molar masses (60 versus 62), yet the
viscosity of ethylene glycol is more than 10 times larger than propanol?
c)
How do you explain the fact that water has the highest surface tension, but lowest viscosity?
28. Which solid in each pair has the higher melting point and why?
a) TiO2(s) or HOOH(s)
b) CCl4(s) or SiCl4(s)
c) Kr(s) or Xe(s)
d) NaCl(s) or CaO(s)
29. Identify the type of crystalline solid formed for the following:
a) Ni
b) F2
c) CH3OH
d) Sn
e) SiC
f) KCl
g) Xe
h) C(graphite)
i) cholesterol C27H45OH
j) diamond
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