Ap Solubility Set I Worksheet
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2
3AP Solubility Set I
1. (80-8) Account for the difference in solubility described in each of the following experimental observations (write
reactions!):
(a) BaCO
, BaSO
, and BaSO
are only slightly soluble in water, but the first two dissolve in HCl solution
3
3
4
whereas BaSO
does not.
4
(b) AgCl, Hg
Cl
, and PbCl
are only slightly soluble in water, but AgCl does dissolve in ammonia solution
2
2
2
whereas the other two do not.
(c) Fe(OH)
and Al(OH)
are only slightly soluble in water, but Al(OH)
dissolves in concentrated NaOH
3
3
3
whereas Fe(OH)
does not.
3
2. (84-6) Given solid samples of KI and of (NH
)
CO
. Briefly describe four simple laboratory tests by which these
4
2
3
two compounds can be distinguished. For each test, report the expected result for each compound.
-7
3. (85-1) At 25 °C the solubility product constant, K
, for strontium sulfate, SrSO
, is 7.6 x 10
. The solubility
sp
4
-10
product constant for strontium fluoride, SrF
, is 7.9 x 10
2
(a) What is the molar solubility of SrSO
in pure water at 25 °C?
4
(b) What is the molar solubility of SrF
in pure water at 25 °C?
2
(c) An aqueous solution of Sr(NO
)
is added slowly to 1.0 liter of a well-stirred solution containing 0.020
3
2
-
-2
mole F
and 0.10 mole SO4
at 25 °C. (You may assume that the added Sr(NO
)
solution does not
3
2
materially affect the total volume of the system.) Which salt precipitates first? What is the concentration of
2+
strontium ion, Sr
, in the solution when the first precipitate begins to form?
(d) As more Sr(NO
)
is added to the mixture in (c) a second precipitate begins to form. At that stage, what
3
2
percent of the anion of the first precipitate remains in solution?
-3
4. (90-1) The solubility of iron(II) hydroxide, Fe(OH)
, is 1.43 x 10
gram per liter at 25 °C.
2
(a) Write a balanced equation for the solubility equilibrium.
(b) Write the expression for the solubility product constant, K
, and calculate its value.
sp
(c) Calculate the pH of the saturated solution of Fe(OH)
at 25 °C.
2
-3
-6
(d) A 50.0-milliliter sample of 3.00 x 10
molar FeSO
solution is added to 50.0 milliliters of 4.00 x 10
4
molar NaOH solution. Does a precipitate of Fe(OH)
form? Explain and show calculations to support your
2
answer.
Ý Mg
2+
-
5. (94-1)
MgF
+ 2 F
2(s)
(aq)
(aq)
2+
-3
In a saturated solution of MgF
at 18° C, the concentration of Mg
is 1.21 x 10
molar. The equilibrium is
2
represented by the equation above.
(a) Write the expression for the solubility-product constant, K
, and calculate its value at 18° C.
sp
2+
(b) Calculate the equilibrium concentration of Mg
in 1.000 liter of saturated MgF
solution at 18°C to
2
which 0.100 mole of solid KF has been added. The KF dissolves completely. Assume the volume change is
negligible.
-3
(c) Predict whether a precipitate of MgF
will form when 100.0 milliliters of a 3.00 x 10
molar Mg(NO
)
2
3
2
-3
solution is mixed with 200.0 milliliters of a 2.00 x 10
molar NaF solution at 18°C. Calculations to support
your prediction must be shown.
2+
-3
(d) At 27°C the concentration of Mg
in a saturated solution of MgF
is 1.17 x 10
molar. Is the dissolving
2
of MgF
in water an endothermic or an exothermic process? Give an explanation to support your
2
conclusion.
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