General Chemistry Principles, Patterns, and Applications, 2011

2. The solubility of O 2 in 100 g of H 2 O at varying temperatures and a pressure of 1 atm is given in the following
table:
Solubility (g) Temperature (°C)
0.0069 0
0.0054 10
0.0043 20
a. What is the value of the Henry’s law constant at each temperature?
b. Does Henry’s law constant increase or decrease with increasing temperature?
c. At what partial pressure of O 2 would the concentration of O 2 in water at 0°C be the same
as the concentration in water at 20°C at a partial pressure of 1 atm?
d. Assuming that air is 20% O 2 by volume, at what atmospheric pressure would the
O 2 concentration be the same at 20°C as it is at atmospheric pressure and 0°C?
ANSWER
1.
a. 0.678 L CO 2
b. k 0 ° C = 7.61 × 10 −2 M/atm, k 20 ° C = 3.84 × 10 −2 M/atm
[1] The phenomenon is similar to that involved in the increase in vapor pressure of a pure liquid
with increasing temperature, as discussed in Chapter 11 "Liquids". In the case of vapor
pressure, however, it is attractive forces between solvent molecules that are being overcome
by the added thermal energy when the temperature is increased.
13.4 Effects of Temperature and Pressure on Solubility
L E A R N I N G O B JE C T I V E
1. To understand the relationship among temperature, pressure, and solubility.
Experimentally it is found that the solubility of most compounds depends strongly on temperature and, if a gas, on
pressure as well. As we shall see, the ability to manipulate the solubility by changing the temperature and pressure
has several important consequences.
Effect of Temperature on the Solubility of Solids
Figure 13.9 "Solubilities of Several Inorganic and Organic Solids in Water as a Function of
Temperature" shows plots of the solubilities of several organic and inorganic compounds in water as a
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