Chapter 16:
Energy and Chemical Change
Practice Test
1.
Chemical reactions and physical changes that absorb energy from their surroundings are __________.
a.
mesothermic
b.
endothermic
c.
exothermic
d.
isothermic
Hint
2.
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.
35°C
b.
40°C
c.
25°C
d.
30°C
Hint
3.
Which of the following processes occurs with a decrease in entropy?
a.
dissolving salt in water
b.
boiling water
c.
freezing of water
d.
sublimation of dry ice
Hint
4.
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.
-951.1 kJ
b.
-704.2 kJ
c.
-835 kJ
d.
-922.6 kJ
Hint
5.
How much heat energy is liberated when 11.0 grams of manganese is used in the formation of Mn
2
O
3
?
Δ
H
f
° for Mn
2
O
3
is -962.3 kJ/mol
a.
460 kJ
b.
289 kJ
c.
192 kJ
d.
96.3 kJ
Hint
6.
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.
0.38 J/(g•°C)
b.
0.62 J/(g•°C)
c.
3.8 × 10
2
J/(g•°C)
d.
0.076 J/(g•°C)
Hint
7.
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.
beryllium 1.82 J/(g•°C)
b.
gold 0.129 J/(g•°C)
c.
calcium 0.653 J/(g•°C)
d.
copper 0.385 J/(g•°C)
Hint
8.
How much heat is absorbed in the complete reaction of 3.00 grams of SiO
2
with excess carbon in the reaction below?
Δ
H
° for the reaction is +624.7 kJ.
SiO
2
(g) + 3C(s) → SiC(s) + 2CO(g)
a.
31.2 kJ
b.
1.13 × 10
5
kJv
c.
5.06 kJ
d.
366 kJ
Hint
9.
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.
0.676 kJ
d.
0.170 kJ
Hint
10.
Which of the following occurs with an increase in entropy?
a.
the reaction PCl
3
(g) + Cl
2
(g) → PCl
5
(g)
b.
twenty nickels taken from a box and arranged tails up on a table
c.
evaporation of carbon tetrachloride
d.
precipitation of silver chloride from a solution of silver ions and chloride ions
Hint
11.
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
12.
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.
exothermic reaction, heat is lost from the system
c.
exothermic reaction, heat is gained by the system
d.
endothermic reaction, heat is gained by the system
Hint
13.
Calculate the enthalpy for the reaction below
2ZnS(s) + 3O
2
(g) → 2ZnO(s) + 2SO
2
(g)
Δ
H
f
° (kJ/mol) -206.0 0 -348.3 -296.8
a.
-270.6 kJ
b.
+270.6 kJ
c.
+878.2 kJ
d.
-878.2 kJ
Hint
14.
A process can never be spontaneous when it is _________.
a.
exothermic, and there is an increase in disorder
b.
exothermic, and there is an increase in disorder
c.
endothermic, and there is an increase in disorder
d.
endothermic, and there is a decrease in disorder
Hint
15.
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.
HCl + NaOH → NaCl + H
2
O
c.
NaOH and water
d.
aqueous HCl and NaOH
Hint
16.
How much heat is required to melt 200 grams of ice? The heat of fusion is 333 J/g.
a.
6.66 kJ
b.
66.6 kJ
c.
1.66 J
d.
666 J
Hint
17.
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.
-1643 kJ
b.
-2470 kJ
c.
-1409 kJ
d.
-2599 kJ
Hint
18.
Which of the following substances has an enthalpy value of 0 at 298 K and 1 atmosphere of pressure?
a.
HCl(aq)
b.
CO
2
(g)
c.
Na(s)
d.
NaOH(s)
Hint
19.
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.
540 J
c.
1.14 × 10
4
J
d.
270 J
Hint
20.
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
