Energy and Chemical Change
Practice Test
1.
How many moles of sulfur are present in 5 moles of H
2
SO
4
?
a.
5 mol
b.
2 mol
c.
10 mol
d.
1 mol
2.
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.
0.676 kJ
b.
0.170 kJ
c.
5.73 kJ
d.
2.83 kJ
3.
One calorie is equal to 4.184J. How much energy in joules is supplied by a breakfast bar containing 170 nutritional calories?
a.
170 J
b.
1.7 x 10
5
J
c.
7.11 x 10
5
J
d.
711 J
4.
The substance that limits the extent of a chemical reaction has a special name. What is this substance called?
a.
limiting product
b.
excess product
c.
limiting reactant
d.
excess reactant
5.
In a glass of sugar water, which substance is the solute?
a.
glass
b.
water
c.
none of the above
d.
sugar
6.
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.
-1409 kJ
b.
-1643 kJ
c.
-2470 kJ
d.
-2599 kJ
7.
How many moles of HCl will just react with 0.424 g Ba(OH)
2
?
2HCl + Ba(OH)
2
→ BaCl
2
+ 2H
2
O
a.
2.48 x 10
-3
mol
b.
9.90 x 10
-3
mol
c.
4.94 x 10
-3
mol
d.
1.24 x10
-3
mol
8.
What mass of SrF
2
can be prepared from the reaction of 10.0 g Sr(OH)
2
with excess HF?
Sr(OH)
2
+ 2HF → SrF
2
+ 2H
2
O
a.
9.67 g
b.
9.82 g
c.
10.0 g
d.
10.3 g
9.
A solution that contains less solute per volume of solvent than another solution made from the same components is said to be more ________.
a.
dissolved
b.
concentrated
c.
solvated
d.
dilute
10.
The process of a solvent and a solute completely mixing and forming a solution is ________.
a.
salvation
b.
solvation
c.
ionization
d.
crystallization
11.
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.
neg. 50 kJ
b.
54 kJ
c.
-263 kJ
d.
19 kJ
12.
How many grams of NaCl are dissolved in 500.0 mL of a 0.05M solution of NaCl?
a.
1.46 g
b.
0.05 g
c.
2.92 g
d.
0.29 g
13.
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
14.
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.
12 J
b.
118 J
c.
1.2 x 10
4
J
d.
2.6 x 10
4
J
15.
What is the name given to the relationship that shows that an increase in pressure leads to a decrease in the volume of a gas?
a.
Charles’s law
b.
Avogadro’s number
c.
Gay-Lussac’s law
d.
Boyle’s law
16.
A 0.5-L container of nitrogen gas is heated under constant pressure to the boiling point of water. What is its new volume?
a.
0.86 L
b.
0.79 L
c.
0.5 L
d.
0.64 L
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.
-642 kJ
b.
b. -376 kJ
c.
-775 kJ
d.
376 kJ
18.
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.
12.9°C
b.
6.5°C
c.
87.1°C
d.
93.5°C
19.
At one atmosphere pressure and the melting point of a substance, which statement is true about this general equation? solid 3 liquid
a.
ΔS = 0 for the process
b.
ΔG = 0 for the process
c.
Both ΔH and ΔS = 0 for the process
d.
ΔH = 0 for the process
20.
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 gained by the system
b.
exothermic reaction, heat is lost from the system
c.
endothermic reaction, heat is lost from the system
d.
exothermic reaction, heat is gained by the system
