Energy and Chemical Change
Practice Test
1.
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.
2.83 kJ
c.
5.73 kJ
d.
0.170 kJ
2.
Based on the following equation, how many moles of hydrochloric acid are needed to react with 0.64 moles of potassium permanganate?
2KMnO
4
+ 8 HCl → 3 Cl
2
+ 2 MnO
2
+ 4 H
2
O + 2KCl
a.
0.21 mol HCl
b.
2.7 mol HCl
c.
5.1 mol HCl
d.
0.64 mol HCl
3.
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
4.
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.
269 J
b.
10.8 J
c.
22.4 J
d.
334 J
5.
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.
-263 kJ
b.
19 kJ
c.
neg. 50 kJ
d.
54 kJ
6.
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.
376 kJ
b.
-642 kJ
c.
-775 kJ
d.
b. -376 kJ
7.
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.
0.076 J/(g·°C)
d.
3.8 ´ 102 J/(g·°C)
8.
A gas occupies 2.0 L at STP. What volume will the gas occupy if the pressure is increased to 2.0 atm, and the temperature is kept constant?
a.
2.0 L
b.
0.50 L
c.
4.0 L
d.
1.0 L
9.
What is the mole fraction of ethanol (C
2
H
5
OH) in a solution of 47.5 g of ethanol in 850 g of water?
a.
0.032
b.
0.18
c.
0.021
d.
0.98
10.
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.
10.0 g
b.
9.67 g
c.
10.3 g
d.
9.82 g
11.
A sample of gas is held in a 10.0-L volume at 175 kPa. The temperature is kept constant while the volume is decreased until the pressure is 350 kPa. What is the new volume of the gas?
a.
1.0 L
b.
175 L
c.
5.0 L
d.
10.0 L
12.
At one atmosphere pressure and the melting point of a substance, which statement is true about this general equation? solid 3 liquid
a.
ΔH = 0 for the process
b.
ΔS = 0 for the process
c.
Both ΔH and ΔS = 0 for the process
d.
ΔG = 0 for the process
13.
The process of a solvent and a solute completely mixing and forming a solution is ________.
a.
ionization
b.
crystallization
c.
salvation
d.
solvation
14.
In the chemical reaction below, 3.27 grams of Zn are reacted with 3.30 grams of HCl. Which component will limit the reaction?
Zn + 2HCl → ZnCl
2
+ H
2
a.
H
2
b.
HCl
c.
Zn
d.
ZnCl
2
15.
In a glass of sugar water, which substance is the solute?
a.
glass
b.
sugar
c.
none of the above
d.
water
16.
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.
9.90 x 10
-3
mol
b.
2.48 x 10
-3
mol
c.
4.94 x 10
-3
mol
d.
1.24 x10
-3
mol
17.
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.
-2470 kJ
b.
-1409 kJ
c.
-2599 kJ
d.
-1643 kJ
18.
Calculate the molarity of 0.75 L of a solution containing 0.83 g of dissolved KCl.
a.
0.015 M
b.
1.1 M
c.
0.75 M
d.
6.2
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.
96.3 kJ
d.
192 kJ
20.
Which of the following substances has an enthalpy value of 0 at 298 K and 1 atmosphere of pressure?
a.
CO
2
(g)
b.
Na(s)
c.
HCl(aq)
d.
NaOH(s)
