Chapter 16:
Energy and Chemical Change
Practice Test
1.
Calculate the free energy for the following reaction at 25°C.
2ZnS(s) + 3O
2
(g) → 2ZnO(s) + 2SO
2
(g)
Δ
H
° (kJ/mol) -205.6 0 -348.3 -296.8
Δ
S
° v(J/mol•K) 57.5 205.0 43.64 248.1
a.
-704.2 kJ
b.
-922.6 kJ
c.
-951.1 kJ
d.
-835 kJ
Hint
2.
Calculate the Δ
G
° for the reaction below.
2C
2
H
2
(g) + 5O
2
(g) → 4CO
2
(g) + 2H
2
O(l)
Δ
G
° (kJ/mol) 209.2 0 -394.4 -237.2
a.
-2599 kJ
b.
-2470 kJ
c.
-1643 kJ
d.
-1409 kJ
Hint
3.
The same amount of heat is added to a 10-g sample of each of the following metals. If each metal is initially at 20.0°C, which metal will reach the highest temperature?
a.
copper 0.385 J/(g•°C)
b.
beryllium 1.82 J/(g•°C)
c.
calcium 0.653 J/(g•°C)
d.
gold 0.129 J/(g•°C)
Hint
4.
The heat content of a system at constant pressure is defined as the ___________.
a.
work
b.
entropy
c.
heat
d.
enthalpy
Hint
5.
Which of the following occurs with an increase in entropy?
a.
evaporation of carbon tetrachloride
b.
the reaction PCl
3
(g) + Cl
2
(g) → PCl
5
(g)
c.
twenty nickels taken from a box and arranged tails up on a table
d.
precipitation of silver chloride from a solution of silver ions and chloride ions
Hint
6.
Which of the following processes occurs with a decrease in entropy?
a.
sublimation of dry ice
b.
freezing of water
c.
boiling water
d.
dissolving salt in water
Hint
7.
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.
-299 kJ
b.
+114 kJ
c.
+299 kJ
d.
-114 kJ
Hint
8.
A body in motion possesses kinetic energy because of its __________.
a.
position
b.
motion
c.
composition
d.
inertia
Hint
9.
Chemical reactions and physical changes that absorb energy from their surroundings are __________.
a.
exothermic
b.
endothermic
c.
mesothermic
d.
isothermic
Hint
10.
Calculate the entropy change for the reaction below.
N
2
(g) + 3H
2
(g) → 2NH
3
(g)
S
° (J/mol•K) 191.5 130.6 192.3
a.
-129.7 J/K
b.
-198.7 J/K
c.
76.32 J/K
d.
303.2 J/K
Hint
11.
Given the following information,
SO
3
(g) + H
2
O(l) → H
2
SO
4
(l) Δ
H
° = -133 kJ
Pb(s) + PbO
2
(s) + 2H
2
SO
4
(l) → 2PbSO
4
(s) + 2H
2
O(l) Δ
H
° = -509 kJ
calculate the Δ
H
° for the reaction below.
Pb(s) + PbO
2
(s) + 2SO
3
(g) → 2PbSO
4
(s)
a.
-642 kJ
b.
-376 kJ
c.
-775 kJ
d.
+376 kJ
Hint
12.
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 an increase in disorder
Hint
13.
At one atmosphere pressure and the melting point of a substance, which statement is true about this general equation?
solid 3 liquid
a.
Δ
S
= 0 for the process
b.
Δ
H
= 0 for the process
c.
Both Δ
H
and Δ
S
= 0 for the process
d.
Δ
G
= 0 for the process
Hint
14.
If 5.0 grams of copper cools from 35.0°C to 22.6°C and loses 23.6 joules of heat, what is the specific heat of copper?
a.
3.8 × 10
2
J/(g•°C)
b.
0.076 J/(g•°C)
c.
0.38 J/(g•°C)
d.
0.62 J/(g•°C)
Hint
15.
Calculate the amount of heat absorbed by 10.0 grams of ice at -15.0°C as it is converted to liquid water at 50.0°C. The specific heat of H
2
O(s) = 2.09 J/(g•°C). The specific heat of H
2
O(l) = 4.18 J/(g•°C). The heat of fusion is 333 J/g.
a.
5.73 kJ
b.
2.83 kJ
c.
0.170 kJ
d.
0.676 kJ
Hint
16.
The specific heat of aluminum is 0.900 J/(g•°C). How many joules of heat are absorbed by 30.0 g of aluminum if it is heated from 20.0°C to 40.0°C?
a.
812 J
b.
270 J
c.
540 J
d.
1.14 × 10
4
J
Hint
17.
What is the final temperature of a mixture of chromium metal and water when 50.0 grams of chromium at 15°C (specific heat = 0.448 J/(g•°C)) is added to 25 mL of water (specific heat = 4.18 J/(g•°C)) at 45°C? The density of water is 1 g/mL.
a.
40°C
b.
30°C
c.
25°C
d.
35°C
Hint
18.
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.
exothermic reaction, heat is lost from the system
b.
endothermic reaction, heat is lost from the system
c.
endothermic reaction, heat is gained by the system
d.
exothermic reaction, heat is gained by the system
Hint
19.
How much heat is required to melt 200 grams of ice? The heat of fusion is 333 J/g.
a.
666 J
b.
6.66 kJ
c.
1.66 J
d.
66.6 kJ
Hint
20.
In the chemical reaction between aqueous solutions of hydrochloric acid (HCl) and sodium hydroxide (NaOH), what is the chemical system?
a.
HCl and water
b.
NaOH and water
c.
aqueous HCl and NaOH
d.
HCl + NaOH → NaCl + H
2
O
Hint
