Energy and Chemical Change
Practice Test
1.
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.
-299 kJ
c.
114 kJ
d.
299 kJ
2.
How much heat is required to melt 200 grams of ice? The heat of fusion is 333 J/g.
a.
666 J
b.
66.6 kJ
c.
d. 6.66 kJ
d.
c. 1.66 J
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.
calcium 0.653 J/(g·°C)
b.
gold 0.129 J/(g·°C)
c.
beryllium 1.82 J/(g·°C)
d.
copper 0.385 J/(g·°C)
4.
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.
+878.2 kJ
b.
+270.6 kJ
c.
-270.6 kJ
d.
-878.2 kJ
5.
A body in motion possesses kinetic energy because of its __________.
a.
motion
b.
inertia
c.
position
d.
composition
6.
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
7.
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.
54 kJ
b.
19 kJ
c.
neg. 50 kJ
d.
-263 kJ
8.
The temperature of a 2.5 kg sample of silver was heated from 25°C to 45°C. How much energy was absorbed by the silver?
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.
118 J
b.
12 J
c.
2.6 x 10
4
J
d.
1.2 x 10
4
J
9.
One calorie is equal to 4.184J. How much energy in joules is supplied by a breakfast bar containing 170 nutritional calories?
a.
711 J
b.
7.11 x 10
5
J
c.
170 J
d.
1.7 x 10
5
J
10.
Calculate the ΔG° for the reaction:
2C
2
H
2
(g) + 5O
2
(g) → 4CO
2
(g) + 2H
2
O(l)ΔG° (kJ/mol)209.2, 0, -394.4, -237.2
a.
-1643 kJ
b.
-1409 kJ
c.
-2470 kJ
d.
-2599 kJ
11.
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 gained by the system
c.
endothermic reaction, heat is lost from the system
d.
exothermic reaction, heat is gained by the system
12.
How much heat is evolved when 27.0 g of glucose is burned according to this equation?
C
6
H
12
O
6
+ 6O
2
→ 6CO
2
+ 6H
2
O; Δ H comb. = -2808kJ
Specific Heats of Common Substances at 298 K (25°C)
Substance
Specific heat
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.
136 kJ
b.
421 kJ
c.
421 J
d.
280 kJ
13.
A process can never be spontaneous when it is _________.
a.
exothermic, and there is an increase in disorder
b.
endothermic, and there is an increase in disorder
c.
endothermic, and there is a decrease in disorder
d.
exothermic, and there is a decrease in disorder
14.
At one atmosphere pressure and the melting point of a substance, which statement is true about this general equation? solid 3 liquid
a.
Both ΔH and ΔS = 0 for the process
b.
ΔS = 0 for the process
c.
ΔG = 0 for the process
d.
ΔH = 0 for the process
15.
Which of the following processes occurs with a decrease in entropy?
a.
sublimation of dry ice
b.
freezing of water
c.
dissolving salt in water
d.
boiling water
16.
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.
0.170 kJ
b.
2.83 kJ
c.
5.73 kJ
d.
0.676 kJ
17.
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.
b. -376 kJ
b.
-642 kJ
c.
376 kJ
d.
-775 kJ
18.
How much heat is absorbed in the complete reaction of 3.00 grams of SiO2 with excess carbon in the reaction below? ΔH° for the reaction is +624.7 kJ.
SiO
2
(g) + 3C(s) → SiC(s) + 2CO(g)
a.
1.13 ´ 105 kJ
b.
366 kJ
c.
5.06 kJ
d.
31.2 kJ
19.
How much heat energy is liberated when 11.0 grams of manganese is used in the formation of Mn
2
O
3
?
ΔH
f
° for Mn
2
O
3
is -962.3 kJ/mol
a.
289 kJ
b.
460 kJ
c.
192 kJ
d.
96.3 kJ
20.
Which of the following substances has an enthalpy value of 0 at 298 K and 1 atmosphere of pressure?
a.
NaOH(s)
b.
CO
2
(g)
c.
HCl(aq)
d.
Na(s)
21.
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.
25°C
b.
40°C
c.
30°C
d.
35°C
