freezing-point depression and boiling-point
elevation?
26. What is the relationship between the attractive
forces between ions in aqueous solutions and
the apparent degree of ionization of those ions?
8.
Problems
1. Write the equation for the dissolving of each of
the following ionic compounds in water:
(a) KI (b) NaN03 (c) MgCl2 (d) Na2S04
(e) AI2(S04h.
2. For the compounds listed in the previous
problem, determine the number of moles of
each ion produced, as well as the total number
of moles produced when 1 mol of each
compound dissolves in water.
3. Write the equation for dissolving each of the
following in water and then indicate the total
number of moles of solute ions formed:
(a) 0.50 mol strontium nitrate
(b) 0.50 mol
sodium phosphate
(c) 0.275 mol potassium
sulfide (d) 0.15 mol aluminum sulfate.
4. For each of the following slightly soluble
compounds, write the equations for the
solubility equilibria:
(a) C02S3(S)
(b) PbS(s) (c) PbCr04(s)
5. Using Thble 15-1, write the balanced chemical
equation (term used in Chapters 8 and 9) that
represents each of the following possible doublereplacement reactions occurring in aqueous
solutions. Indicate likely precipitates with the
(s) designation: (a) iron(II) nitrate(aq) +
potassium sulfide(aq) ~ (b) mercury(II)
bromide(aq) + sodium sulfide(aq) ~
(c) sodium hydroxide(aq) + magnesium
chloride(aq) ~ (d) sodium chloride(aq) +
magnesium nitrate(aq) ~
6. Use Thble 15-1 to write the balanced chemical
equation, to write the overall ionic equation, to
identify the spectator ions and possible
precipitates, and to write the '1et ionic equation
(a) silver
for each of the following reactions:
nitrate(aq) + sodium iodide(aq) ~
(b) mercury(II) chloride(aq) + potassium
sulfide(aq) ~ (c) aluminum nitrate(aq) +
barium hydroxide(aq) ~ (d) copper(II)
chloride(aq) + ammonium phosphate(aq) ~
(e) iron(III) iodide(aq) + calcium
chromate(aq) ~
7. Given 1.00 m aqueous solutions of each of the
9.
10.
11.
12.
following substances, what is the expected
change in the freezing point of the
solvent? (a) KI (b) CaCl2 (c) Ba(N03b
(d) C12H22011 (e) AI2(S04h
What is the anticipated change in the freezing
point of an aqueous solution that is 0.015 m
AICI3?
What is the fn~ezing point of a solution
containing 85.0 g of NaCI dissolved in 450. g of
water?
Determine the boiling point of a solution made
by dissolving 25.0 g of barium chloride in
0.150 kg of water.
The change in the boiling point of an aqueous
solution of potassium iodide is 0.65Co.
Determine the apparent molal concentration of
potassium iodide.
The freezing point of an aqueous solution of
barium nitrate is - 2.65°C. Determine the
apparent molal concentration of barium nitrate.
Application Questions
1. Explain the basis for the H20 molecules in the
formulas of such compounds as CuS04,5H20
and Na2C03,lOH20.
2. An ionic solid dissolves in water. The
thermometer in the solution indicates a
temperature drop of lOCO.Is the dissolving
process for this substance endothermic or
exothermic? Explain.
3. Discuss one function of electrolytes in the
human body.
4. Explain why hydrogen chloride as a pure liquid,
or in solution in a nonpolar solvent, does not
conduct an electric current but, when dissolved
in water, the resulting hydrogen chloride
solution does conduct.
5. Explain how the test solution in a conductivity
apparatus serves as a switch in the circuit and
how such an apparatus can be used as a measure
of conductivity.
6. Explain the difference between a concentrated
solution of a weak electrolyte and a dilute
solution of a strong electrolyte,
7. Generally speaking, water is a nonconductor and
a nonelectrolyte; yet we are constantly concerned
about dropping hair dryers or other electrical
appliances into the bathtub. Explain the seeming
inconsistency in this appropriate warning.
8. Explain the Debye-Huckel theory.