Chemistry TB

AP Ch 12 Quiz

Multiple Choice
Identify the letter of the choice that best completes the statement or answers the question.

____   1.   Rank the following pressures in increasing order of magnitude: 623 mm Hg, 133 kPa, 0.155 atm, and 0.500 bar.
a.   0.500 bar < 623 mm Hg < 133 kPa < 0.155 atm
b.   0.155 atm < 0.500 bar < 623 mm Hg < 133 kPa
c.   0.155 atm < 623 mm Hg < 0.500 bar < 133 kPa
d.   623 mm Hg < 0.500 bar < 133 kPa < 0.155 atm
e.   133 kPa < 0.155 atm < 0.500 bar < 623 mm Hg


____   2.   At 0.984 atm, the height of mercury in a barometer is 74.8 cm. If the mercury were replaced with water, what height of water (in centimeters) would be supported at this pressure? The densities of Hg and H2O are 13.5 g/cm3 and 1.00 g/cm3, respectively.
a.   5.54 cm
b.   13.3 cm
c.   994 cm
d.   1.01 ? 103 cm
e.   1.84 ? 105 cm


____   3.   If the volume of a confined gas is quadrupled while its temperature remains constant, what change will be observed?
a.   The pressure of the gas will decrease to 1/4 its original value.
b.   The pressure of the gas will quadruple.
c.   The density of the gas will decrease to 1/2 its original value.
d.   The average velocity of the molecules will quadruple.
e.   The average velocity of the molecules will double.


____   4.   A tightly sealed 5.0-L flask contains 781 mm Hg of Ar at 19 ?C. The flask is heated until the pressure is doubled. What is the temperature of the gas?
a.   -127 ?C
b.   38 ?C
c.   95 ?C
d.   149 ?C
e.   311 ?C


____   5.   A 0.225-L flask contains CH4 at 27 ?C and 318 mm Hg. What is the pressure of the CH4 if the volume is increased to 0.500 L and the temperature increased to 95 ?C?
a.   117 mm Hg
b.   176 mm Hg
c.   503 mm Hg
d.   508 mm Hg
e.   867 mm Hg


____   6.   Avogadro's hypothesis states that equal volumes of gases under the same conditions of temperature and pressure have equal ____.
a.   densities
b.   particle velocities
c.   molar masses
d.   numbers of particles
e.   masses


____   7.   What volume of CO2 at 15 ?C and 1.50 atm contains the same number of molecules as 0.410 L of O2 at 35 ?C and 3.00 atm?
a.   0.192 L
b.   0.219 L
c.   0.767 L
d.   0.820 L
e.   1.14 L


____   8.   If 3.67 g CO2 gas is introduced into an evacuated 2.50 L flask at 65 ?C, what is the pressure inside the flask? (R = 0.08206 L•atm/mol•K)
a.   0.178 atm
b.   0.445 atm
c.   0.925 atm
d.   40.7 atm
e.   496 atm


____   9.   A 50.0 L cylinder of Ar has a pressure of 137 atm at 25 ?C. What mass of Ar is inside the cylinder? (R = 0.08206 L•atm/mol•K)
a.   0.143 g
b.   4.48 g
c.   918 g
d.   2.80 ? 102 g
e.   1.12 ? 104 g


____   10.   Which of the following gases has the greatest density at 25 ?C and 5.0 atm?
a.   CH4
b.   O2
c.   N2
d.   F2
e.   CO2


____   11.   If the density of oxygen in air is 0.263 g/L at 25 ?C, what is the pressure of oxygen at 25 ?C? (R = 0.08206 L•atm/mol•K)
a.   0.201 atm
b.   0.344 atm
c.   0.402 atm
d.   2.91 atm
e.   6.43 atm


____   12.   A mass of 1.663 g of an unknown gas is introduced into an evacuated 2.00 L flask. If the pressure in the flask is 0.544 atm at 78 ?C, which of the following gases might be in the flask? (R = 0.08206 L•atm/mol•K)
a.   N2
b.   C2H2
c.   NH3
d.   HCl
e.   N2O


____   13.   What volume of O2, measured at 91.2 ?C and 743 mm Hg, will be produced by the decomposition of 4.88 g KClO3? (R = 0.08206 L•atm/mol•K)

2 KClO3(s) ? 2 KCl(s) + 3 O2(g)

a.   0.305 L
b.   1.22 L
c.   1.83 L
d.   24.0 L
e.   37.4 L


____   14.   If 6.46 L of gaseous ethanol is burned in excess oxygen, what is the maximum volume of carbon dioxide produced? Assume that the temperature of the reactants and products is 425 °C and the pressure remains constant at 1.00 atm.

CH3CH2OH(g) + 3 O2(g) ? 2 CO2(g) + 3 H2O(g)

a.   6.46 L
b.   3.23 L
c.   12.9 L
d.   19.4 L
e.   32.3 L


____   15.   If 4.00 g S8 react with 4.25 L O2 at 39 ?C and 1.00 atm, what is the maximum mass of SO3 produced? (R = 0.08206 L•atm/mol•K)

S8(s) + 12 O2(g) ? 8 SO3(g)

a.   2.83 g
b.   8.86 g
c.   9.99 g
d.   13.3 g
e.   19.9 g


____   16.   The empirical formula of a certain hydrocarbon is CH2. When 0.120 mole of the hydrocarbon is completely combusted with excess oxygen, 17.7 L CO2 gas is produced at 27 ?C and 1.00 atm. What is the molecular formula of the hydrocarbon? (R = 0.08206 L•atm/mol•K)
a.   C2H2
b.   C2H4
c.   C3H6
d.   C5H10
e.   C6H12


____   17.   Nitroglycerin (227.1 g/mol) decomposes according to the reaction below.

4 C3H5N3O9(?) ? 6 N2(g) + 12 CO2(g) + 10 H2O(g) + O2(g)

What total volume of gases is produced at 65 ?C and 744 mm Hg by the decomposition of 5.00 g nitroglycerin? (R = 0.08206 L•atm/mol•K)
a.   5.95 ? 10-3 L
b.   0.120 L
c.   0.624
d.   4.52 L
e.   18.1 L


____   18.   Carbon monoxide reacts with oxygen to form carbon dioxide.

2 CO(g) + O2(g) ? 2 CO2(g)

In a 1.00 L flask, 2.40 atm of CO reacts with 4.50 atm of O2. Assuming that the temperature remains constant, what is the final pressure in the flask?
a.   1.20 atm
b.   2.40 atm
c.   3.30 atm
d.   3.60 atm
e.   5.70 atm


____   19.   A 1.00 L flask at 298 K contains a mixture of Kr and N2 with a total pressure of 0.940 atm. If the mole fraction of Kr is 0.455, what is the mass fraction of Kr?
a.   0.218
b.   0.286
c.   0.455
d.   0.714
e.   0.782


____   20.   What is the root-mean-square velocity of ethane molecules (C2H6) at 273 K?
a.   15.0 m/s
b.   47.2 m/s
c.   275 m/s
d.   476 m/s
e.   652 m/s


____   21.   The average velocity of a gas molecule is
a.   inversely proportional to its kinetic energy.
b.   directly proportional to the gas constant, R.
c.   directly proportional to the square root of its temperature in K.
d.   inversely proportional to the square of its mass.
e.   directly proportional to the square root of its mass.


____   22.   How long will it take 10.0 mL of Cl2 gas to effuse through a porous barrier if it has been observed that 76.3 minutes are required for 10.0 mL of HCl gas to effuse through the same barrier?
a.   54.7 min.
b.   106 min.
c.   148 min.
d.   202 min.
e.   289 min.


____   23.   Non-ideal behavior for a gas is most likely to be observed under conditions of
a.   high temperature and low pressure.
b.   high temperature and high pressure.
c.   low temperature and low pressure.
d.   standard temperature and pressure.
e.   low temperature and high pressure.


Short Answer

   24.   The rate of effusion of a gas is inversely proportional to the ________ of its molar mass.

   25.   A statement of Avogadro's hypothesis is that equal volumes of gases under the same conditions of pressure and temperature will contain equal numbers of ________.

   26.   The ideal gas law can be modified to correct for the errors arising from nonideality. The modified equation is known as the ________ equation of state for a real gas.

   27.   What are two ways in which real gases differ from ideal gases?