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Solving Problems: A Chemistry Handbook
Chemistry: Matter and Change
141
SOLVING PROBLEMS:
A CHEMISTRY HANDBOOK
CHAPTER 14
ϫ 300 g H 2 O ϭ 99 g KCl
According to the graph, the solubility of KCl at 40°C is 40 g KCl
per 100 g H 2 O. Find the amount of KCl that will dissolve in 300 g
of water at 40°C.
ϫ 300 g H 2 O ϭ 120 g KCl
The amount of additional KCl that dissolves at the higher temperature in 300 g of water is the difference between the two amounts.
120 g KCl Ϫ 99 g KCl ϭ 21 g KCl
Practice Problems
1. Use the graph on the previous page to determine each of the
following.
a. the solubility of CaCl 2 at 5°C
b. the solubility of CaCl 2 at 25°C
c. the mass of Ce 2 (SO 4 ) 3 that will dissolve in 50 g of water
at 10°C
d. the mass of Ce 2 (SO 4 ) 3 that will dissolve in 50 g of water
at 0°C
e. the mass of additional KClO 3 that will dissolve in 200 g of
water if the water temperature is raised from 30°C to 90°C
Pressure and solubility The solubility of a gas increases as its
external pressure (its pressure above the solution) increases. This
fact is expressed by Henry’s law, which states that at a given temperature, the solubility (S) of a gas in a liquid is directly proportional
to the pressure (P) of the gas above the liquid, or
ϭ
where S 1 is the solubility of a gas at pressure P 1 , and S 2 is the
solubility of the gas at P 2 .
S 2
ᎏ
P 2
S 1
ᎏ
P 1
▲
40 g KCl
ᎏᎏ
100 g H 2 O
33 g KCl
ᎏᎏ
100 g H 2 O