Reaction Rates
Practice Test
1.
How much heat is required to melt 200 grams of ice? The heat of fusion is 333 J/g.
a.
c. 1.66 J
b.
d. 6.66 kJ
c.
666 J
d.
66.6 kJ
2.
Calculate ΔH° for the following reaction.
Fe
3
O
4
(s) + CO(g) → 3FeO(s) + CO
2
(g) ΔH
f
°(kJ/mol) -1118 -110.5 -272 -393.5
a.
19 kJ
b.
neg. 50 kJ
c.
-263 kJ
d.
54 kJ
3.
What is the density of a sample with a mass of 24.47 g and a volume of 13.2 mL?
a.
1.8537 g/mL
b.
1.9 g.mL
c.
1.854 g/mL
d.
1.85 g/mL
4.
A process can never be spontaneous when it is _________.
a.
endothermic, and there is a decrease in disorder
b.
exothermic, and there is an increase in disorder
c.
endothermic, and there is an increase in disorder
d.
exothermic, and there is a decrease in disorder
5.
How are the rate law and the order for a complex reaction determined?
a.
by calculation
b.
by estimation
c.
by trial and error
d.
by experimentation
6.
What is the name given to a catalyst that exists in the same physical state as the reaction being catalyzed?
a.
heterogeneous catalyst
b.
ephemiral catalyst
c.
homogeneous catalyst
d.
solid-state catalyst
7.
Which of the following processes occurs with a decrease in entropy?
a.
dissolving salt in water
b.
sublimation of dry ice
c.
boiling water
d.
freezing of water
8.
A unit that is defined by a combination of base units is a(n) ________________.
a.
metric unit
b.
English unit
c.
SI unit
d.
derived unit
9.
What is the reaction order for each reactant in the following rate-law expression? Rate = k[A][B]
2
[C]
3
a.
first order for A, first order for B, first order for C
b.
first order for A, second order for B, second order for C
c.
first order for A, second order for B, third order for C
d.
first order for A, second order for B, first order for C
10.
For the reaction below, the enthalpy change is +624.7 kJ. How would you classify this reaction?
SiO
2
(g) + 3C(s) → SiC(s) + 2CO(g)
a.
endothermic reaction, heat is lost from the system
b.
endothermic reaction, heat is gained by the system
c.
exothermic reaction, heat is lost from the system
d.
exothermic reaction, heat is gained by the system
11.
Calculate the enthalpy for the reaction:
2ZnS(s) + 3O
2
(g) → 2ZnO (s) + 2SO
2
(g) ΔH
f
° (kJ/mol) -206.0 0 -348.3 –296.8
a.
+270.6 kJ
b.
-878.2 kJ
c.
-270.6 kJ
d.
+878.2 kJ
12.
Use the data in the table to calculate the average reaction rate expressed in moles Cl
2
consumed per liter per second.
Time (s)
[H
2
] (M)
[Cl
2
] (M)
[HCl] (M)
0
0.03
0.05
0.55
10
0.005
0.025
0.05
a.
0.003 mol/(L s)
b.
0.030 mol/(L s)
c.
0.002 mol/(L s)
d.
0.0025 mol/(L s)
13.
When you increase the temperature of a chemical reaction, the ____________.
a.
reaction rate does not change
b.
reaction speeds up
c.
reaction slows down
d.
reaction stops
14.
What is the slowest of the elementary steps in a complex reaction called?
a.
fast step
b.
propagating step
c.
rate-limiting step
d.
mechanism
15.
What Greek symbol is used to represent change?
a.
Σ
b.
Δ
c.
→
d.
∈
16.
The temperature of a 25.0 g sample of aluminum changed from 25°C to37°C when heated. How much energy was absorbed by the aluminum?
Specific Heats of Common Substances at 298 K (25°C)
Specific heat
Substance J/(g·°C)
Water(l)
(liquid)
4.184
Water(s)
(ice)
2.03
Water(g)
(steam)
2.01
Ethanol(l)
(grain alcohol)
2.44
Aluminum(s)
0.897
Granite(s)
0.803
Iron(s)
0.449
Lead(s)
0.129
Silver(s)
0.235
Gold(s)
0.129
a.
10.8 J
b.
269 J
c.
22.4 J
d.
334 J
17.
A body in motion possesses kinetic energy because of its __________.
a.
motion
b.
inertia
c.
position
d.
composition
18.
From the following data,
H
2
(g) + Cl
2
(g) → 2HCl(g) Δ
H
°v = -185 kJ
2H
2
(g) + O
2
(g) → 2H
2
O(g) Δ
H
° = -483.7 kJ
calculate Δ
H
° for the following reaction.
4HCl(g) + O
2
(g) → 2Cl
2
(g) + 2H
2
O(g)
a.
-114 kJ
b.
114 kJ
c.
299 kJ
d.
-299 kJ
19.
If 500 g of water at 100°C loses 27,000 J of heat, what is the final temperature of the water?
Specific Heats of Common Substances at 298 K (25°C)
Specific heat
Substance J/(g·°C)
Water(l)
(liquid)
4.184
Water(s)
(ice)
2.03
Water(g)
(steam)
2.01
Ethanol(l)
(grain alcohol)
2.44
Aluminum(s)
0.897
Granite(s)
0.803
Iron(s)
0.449
Lead(s)
0.129
Silver(s)
0.235
Gold(s)
0.129
a.
93.5°C
b.
6.5°C
c.
12.9°C
d.
87.1°C
20.
What are the individual steps in a complex reaction known as?
a.
elementary steps
b.
complex steps
c.
intermediate steps
d.
rate-determining steps
