584 CHAPTER 14: Solutions
Solid emulsion A colloidal dispersion of a liquid in a solid.
Solid foam A colloidal dispersion of a gas in a solid.
Solid sol A colloidal dispersion of a solid in a solid.
Solvation The process by which solvent molecules surround and
interact with solute ions or molecules.
Supersaturated solution A (metastable) solution that contains
a higher-than-saturation concentration of solute; slight distur-
bance or seeding causes crystallization of excess solute.
Surfactant A “surface-active agent”; a substance that has the abil-
ity to emulsify and wash away oil and grease in an aqueous sus-
pension.
Thermal pollution Introduction of heated waste water into nat-
ural waters.
Tyndall effect The scattering of light by colloidal particles.
van’t Hoff factor, i A number that indicates the extent of dis-
sociation or ionization of a solute; equal to the actual colligative
property divided by the colligative property calculated assum-
ing no ionization or dissociation.Exercises
General Concepts: The Dissolving Process
*001.Support or criticize the statement “Solutions and mix-
tures are the same thing.”
*002.Give an example of a solution that contains each of the
following: (a) a solid dissolved in a liquid; (b) a gas dis-
solved in a gas; (c) a gas dissolved in a liquid; (d) a liquid
dissolved in a liquid; (e) a solid dissolved in a solid. Iden-
tify the solvent and the solute in each case.
*003.There are no truesolutions in which the solvent is gaseous
and the solute is either liquid or solid. Why?
*004.Explain why (a) solute–solute, (b) solvent–solvent, and
(c) solute–solvent interactions are important in deter-
mining the extent to which a solute dissolves in a solvent.
*005.Define and distinguish between dissolution, solvation,
and hydration.
*006.The amount of heat released or absorbed in the dissolu-
tion process is important in determining whether the
dissolution process is spontaneous, meaning, whether it
can occur. What is the other important factor? How does
it influence solubility?
*007.An old saying is that “oil and water don’t mix.” Explain,
on a molecular basis, why this saying is true.
*008.Two liquids, A and B, do not react chemically and are
completely miscible. What would be observed as one is
poured into the other? What would be observed in the
case of two completely immiscible liquids and in the case
of two partially miscible liquids?
*009.Consider the following solutions. In each case, predict
whether the solubility of the solute should be high or low.
Justify your answers. (a) KCl in hexane, C 6 H 14 ; (b) CaCl 2
in H 2 O; (c) C 6 H 14 in H 2 O; (d) CCl 4 in C 6 H 14 ; (e) C 6 H 14
in CCl 4.
*010.Consider the following solutions. In each case predict
whether the solubility of the solute should be high or low.
Justify your answers. (a) HCl in H 2 O; (b) HF in H 2 O;
(c) Al 2 O 3 in H 2 O; (d) S 8 in H 2 O; (e) NaNO 3 in hexane,
C 6 H 14.
*011.For those solutions in Exercise 9 that can be prepared in
“reasonable” concentrations, classify the solutes as non-
electrolytes, weak electrolytes, or strong electrolytes.
*012.For those solutions in Exercise 10 that can be preparedin “reasonable” concentrations, classify the solutes as non-
electrolytes, weak electrolytes, or strong electrolytes.
*013.Both methanol, CH 3 OH, and ethanol, CH 3 CH 2 OH,
are completely miscible with water at room tem-
perature because of strong solvent–solute intermo-
lecular attractions. Predict the trend in solubility
in water for 1-propanol, CH 3 CH 2 CH 2 OH;
1-butanol, CH 3 CH 2 CH 2 CH 2 OH; and 1-pentanol,
CH 3 CH 2 CH 2 CH 2 CH 2 OH.
*014.(a) Does the solubility of a solid in a liquid exhibit an
appreciable dependence on pressure? (b) Is the same true
for the solubility of a liquid in a liquid? Why?
*015.Describe a technique for determining whether or not a
solution contains an electrolyte.
*016.A reagent bottle in the storeroom is labeled as contain-
ing a saturated sodium chloride solution. How can one
determine whether or not the solution is saturated?
0 *17.A handbook lists the value of the Henry’s Law constant
as 3.02 104 atm for ethane, C 2 H 6 , dissolved in water at
25°C. The absence of concentration units on kmeans that
the constant is meant to be used with concentration
expressed as a mole fraction. Calculate the mole fraction
of ethane in water at an ethane pressure of 0.15 atm.
0 *18.The mole fraction of methane, CH 4 , dissolved in water
can be calculated from the Henry’s Law constants of 4.13
104 atm at 25°C and 5.77 104 atm at 50.°C. Calcu-
late the solubility of methane at these temperatures for a
methane pressure of 10. atm above the solution. Does the
solubility increase or decrease with increasing tempera-
ture? (See Exercise 17 for interpretation of units.)
*019.Choose the ionic compound from each pair for which the
crystal lattice energy should be the most negative. Justify
your choice. (a) LiF or LiBr; (b) KF or CaF 2 ; (c) FeF 2 or
FeF 3 ; (d) NaF or KF.
*020.Choose the ion from each pair that should be more
strongly hydrated in aqueous solution. Justify your
choice. (a) Naor Rb; (b) Clor Br; (c) Fe^3 or Fe^2 ;
(d) Naor Mg^2 .
0 *21.The crystal lattice energy for LiBr(s) is 818.6 kJ/mol
at 25°C. The hydration energy of the ions of LiBr is
867.4 kJ/mol at 25°C (for infinite dilution). (a) What is
the heat of solution of LiBr(s) at 25°C (for infinite