Multiple Choice
Identify the
letter of the choice that best completes the statement or answers the question.
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1.
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Which
of the following best describes temperature? a. | heat absorbed or released in a chemical or physical
change | b. | a measure of the average kinetic energy of the particles in a
sample of matter | c. | heat energy | d. | energy of
change | | |
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2.
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What
is the heat required to raise the temperature of 1 g of a substance by 1 ºC or 1
K? a. | specific
heat | c. | heat
capacity | b. | heat energy | d. | heat of formation | | | | |
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3.
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A 4.0
g sample of iron was heated from 0ºC to 20.ºC. It absorbed 35.2 J of energy as heat. What
is the specific heat of this piece of iron? a. | 2816 J/g·ºC | c. | 2.27 J/g | b. | 2.27
J/g·ºC | d. | 0.44
J/g·ºC | | | | |
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4.
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Enthalpy change is the a. | pressure change of a system at constant
temperature. | b. | entropy change of a system at constant
pressure. | c. | temperature change of a system at constant
pressure. | d. | amount of energy absorbed or lost by a system as heat during a
process at constant pressure. | | |
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Heats of
Formation (kJ/mol) | | Heats of Combustion (kJ/mol) | Substance | Formula | DH0f | | Substance | Formula | DH0c | ammonia(s) | NH3 |
–45.9 | | hydrogen(g) | H2 |
–285.8 | barium
nitrate(s) | Ba(NO3)2 |
–992.1 | | carbon
(graphite)(s) | C | –393.5 | benzene(l) | C6H6 | +49.1 | | carbon monoxide
(g) | CO | –283.0 | calcium chloride(s) | CaCl2 |
–795.4 | | methane (g) | CH4 |
–890.8 | carbon (diamond)
(s) | C | +1.9 | | ethane(g) | C2H6 | –1560.7 | carbon (graphite)(s) | C |
0.0 | | propane(g) | C3H8 | –2219.2 | carbon dioxide(g) | CO2 |
–393.5 | | butane(g) | C4H10 | –2877.6 | copper(II) sulfate(s) | CuSO4 |
–771.4 | | pentane(g) | C5H12 | –3535.6 | ethyne (acetylene)(g) | C2H2 | +228.2 | | hexane(l) | C6H14 | –4163.2 | hydrogen chloride(g) | HCl |
–92.3 | | heptane(l) | C7H16 | –4817.0 | water(l) | H2O |
–285.8 | | octane(l) | C8H18 | –5470.5 | nitrogen dioxide(g) | NO2 |
+33.2 | | ethene (ethylene)(g) | C2H4 | –1411.2 | ozone(g) | O3 | +142.7 | | propene
(propylene)(g) | C3H6 | –2058.0 | sodium chloride(s) | NaCl |
–385.9 | | ethyne
(acetylene)(g) | C2H2 | –1301.1 | sulfur dioxide(g) | SO2 |
–296.8 | | benzene(l) | C6H6 | –3267.6 | zinc sulfate(s) | ZnSO4 |
–980.1 | | toluene(l) | C7H8 | –3910.3 | | | | | | | |
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5.
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What
is the heat of combustion of 1 mol of sulfur to form SO2? a. | –593.6
kJ/mol | c. | 0
kJ/mol | b. | –296.8 kJ/mol | d. | +296.8 kJ/mol | | | | |
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6.
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What
is the heat of formation of ethane, C2H6? a. | –870.7
kJ/mol | c. | +83.7
kJ/mol | b. | –83.7 kJ/mol | d. | +870.7 kJ/mol | | | | |
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7.
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Spontaneous reactions are driven by a. | decreasing
enthalpy and decreasing entropy. | b. | decreasing enthalpy and increasing
entropy. | c. | increasing enthalpy and decreasing
entropy. | d. | increasing enthalpy and increasing
entropy. | | |
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8.
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Which
of the following is a measure of the disorder in a system? a. | entropy | c. | free
energy | b. | enthalpy | d. | temperature | | | | |
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9.
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Which
of the following substances has the highest entropy? a. | steam | c. | liquid
water | b. | ice water | d. | crushed ice | | | | |
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10.
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What
is the sequence of steps in a reaction called? a. | heterogeneous reaction | c. | overall reaction | b. | rate
law | d. | reaction
mechanism | | | | |
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11.
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To be
effective, a collision requires a. | sufficient energy. | b. | a favorable
orientation. | c. | sufficient energy and a favorable
orientation. | d. | a reaction mechanism. | | |
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12.
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Raising the temperature of reactants in a system a. | increases the
average molecular motion. | b. | decreases the average molecular
motion. | c. | has no effect on the average molecular
motion. | d. | disturbs the system so that the collision theory no longer
applies. | | |
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13.
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The
minimum energy required for an effective collision is called a. | energy of
enthalpy. | c. | free
energy. | b. | activation energy. | d. | kinetic energy. | | | | |
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14.
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A
short-lived structure formed during a collision is a(n) a. | reagent. | c. | activated
complex. | b. | catalyst. | d. | inhibitor. | | | | |
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15.
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How
does the energy of the activated complex compare with the energies of reactants and
products? a. | It is lower than
the energy of both reactants and products. | b. | It is lower than the energy of reactants but higher than the
energy of products. | c. | It is higher than the energy of reactants but lower than the
energy of products. | d. | It is higher than the energy of both reactants and
products. | | |
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16.
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Activation energy is a. | the energy required to form the activated
complex. | b. | the net energy required to turn reactants into
products. | c. | the heat of reaction. | d. | free
energy. | | |
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17.
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Which
statement correctly describes the energy changes that occur when bonds form and when bonds
break? a. | Breaking bonds
is endothermic, and forming bonds is exothermic. | b. | Breaking bonds
is exothermic, and forming bonds is endothermic. | c. | Both are
exothermic. | d. | Both are endothermic. | | |
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18.
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If
the surface area of reactants is larger, a. | the reaction rate is generally
higher. | c. | the reaction
rate is not affected. | b. | the reaction rate is generally
lower. | d. | the
rate-determining step is eliminated. | | | | |
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19.
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Catalysts generally affect chemical reactions by a. | increasing the
temperature of the system. | b. | increasing the surface area of the
reactants. | c. | providing an alternate pathway with a lower activation
energy. | d. | providing an alternate pathway with a higher activation
energy. | | |
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20.
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If
doubling the concentration of a reactant doubles the rate of the reaction, the concentration of the
reactant appears in the rate law with a(n) a. | exponent of 1. | c. | exponent of 4. | b. | exponent of
2. | d. | coefficient of
2. | | | | |
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21.
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The
rate for a reaction between reactants X, Y, and Z is directly proportional to [X] and to [Y], and
proportional to the square of [Z]. What is the rate law for this reaction? a. | R =
k[X][Y][Z]2 | c. | R =
k[X][Y][2Z]2 | b. | R = k[X][Y][2Z] | d. | | | | | |
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22.
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Which
of the following reactions would be expected to be the slowest?
a. | Ag+(aq) + Cl-(aq) à AgCl(s)
| c. | CH4(g) + 2O2(g) à
CO2(g) + 2H2O(g)
| b. | H2(aq) + CN-(aq) à
HCN(aq)
| d. | Pb2+(aq) + CrO42-(aq) à
PbCrO4(s) | | | | |
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Short Answer
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23.
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reaction has an activation energy of 40 kJ and an overall energy change of reaction of -100 kJ. In
each of the following potential energy diagrams, the horizontal axis is the reaction coordinate and
the vertical axis is potential energy in kJ. Which potential energy diagram best describes this
reaction?___________________________________
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24.
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From the following data at
25øC,
H2(g) +
Cl2(g) à
2HCl(g) ?Ho = -185
kJ
2H2(g) +
O2(g) à
2H2O(g)
?Ho = -483.7 kJ
Calculate ?Ho at
25øC for the reaction below.
4HCl(g) + O2(g) à
2Cl2(g) + 2H2O(g)
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25.
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determine the rate expression for the following:
(C2H5)2(NH2)2
+ I2 ®
(C2H5)2N2 +
2HI
Expt.
(C2H5)2(NH2)2(M)
I2(M)
Initial Rate of Formation of
(C2H5)2N2
(M/s)
1
0.010
0.010
2.0
2
0.010
0.020
4.0
3
0.030
0.020
12
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