Section 16.3
Thermochemical Equations
Practice Test
1.
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.
280 kJ
c.
421 kJ
d.
421 J
Hint
2.
How much heat is required to melt 200 grams of ice? The heat of fusion is 333 J/g.
a.
66.6 kJ
b.
666 J
c.
c. 1.66 J
d.
d. 6.66 kJ
Hint
3.
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.
0.676 kJ
c.
0.170 kJ
d.
2.83 kJ
Hint
4.
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
5.
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.
b. -376 kJ
c.
-642 kJ
d.
-775 kJ
Hint
