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52. The correct answer is (D). Since the solution reaction is exothermic, lowering the temperature of
the water will increase the solubility of Na
2
SO
4
. This is an application of Le Chatlier’s principle.
53. The correct answer is (D). Solid Ag
2
CrO
4
dissociates into 2Ag
+
+ CrO
4
–2
ions. K
sp
is the equilib-
rium constant for this reaction after eliminating the [Ag
2
CrO
4
] solid term from the denominator.
54. The correct answer is (E). One liter of solution contains 300ml of H
2
SO
4
. 300ml of H
2
SO
4
weighs
540g. 540g of H
2
SO
4
equal 5.5 moles.
55. The correct answer is (D). A spontaneous oxidation-reduction reaction has a positive so the half-
reactions must be combined as:
Mn + Zn
+2
= Zn + Mn
+2
De
° = .40V
K
eq
= 10
n
ε°/.059
= 10
2 
× .4/.059
= 10
.8/.059
n = number of electrons transferred per atom
56. The correct answer is (C). Using PV = nRT, solve for n = PV/RT where T = 300
°K.
57. The correct answer is (C). Both Hg
+2
and Cu
+2
belong to the acid hydrogen group. HgS is less soluble
than CuS in 3M HNO
3
.
58. The correct answer is (E). Given the assumption, what the question is looking for is the amount of
compound that will dissolve to produce the most ions. One mole of CaCl
2
produces three moles of ions.
59. The correct answer is (D). The balanced equation is: 2Fe(OH)
3
+ 4(OH
–
) + 3ClO
–
= 2FeO
4
–2
+
5H
2
O + 3Cl
–
.
For every mole of Fe(OH)
3
consumed, 2.5 moles of H
2
O are produced.
2.5moles 
× 18g/mole = 45g.