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General Chemistry Principles, Patterns, and Applications, 2011

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NUMERICAL P ROBLEMS<br />

1. The solubility of CO 2 in water at 0°C <strong>and</strong> 1 atm is 0.335 g/100 g of H 2 O. At 20°C <strong>and</strong> 1 atm, the solubility of<br />

CO 2 in water is 0.169 g/100 g of H 2 O.<br />

a. What volume of CO 2 would be released by warming 750 g of water saturated with<br />

CO 2 from 0°C to 20°C?<br />

b. What is the value of the Henry’s law constant for CO 2 under each set of conditions?<br />

2. The solubility of O 2 in 100 g of H 2 O at varying temperatures <strong>and</strong> a pressure of 1 atm is given in the following<br />

table:<br />

Solubility (g) Temperature (°C)<br />

0.0069 0<br />

0.0054 10<br />

0.0043 20<br />

a. What is the value of the Henry’s law constant at each temperature?<br />

b. Does Henry’s law constant increase or decrease with increasing temperature?<br />

c. At what partial pressure of O 2 would the concentration of O 2 in water at 0°C be the same<br />

as the concentration in water at 20°C at a partial pressure of 1 atm?<br />

d. Assuming that air is 20% O 2 by volume, at what atmospheric pressure would the<br />

O 2 concentration be the same at 20°C as it is at atmospheric pressure <strong>and</strong> 0°C?<br />

ANSWER<br />

1.<br />

a. 0.678 L CO 2<br />

b. k 0 ° C = 7.61 × 10 −2 M/atm, k 20 ° C = 3.84 × 10 −2 M/atm<br />

[1] The phenomenon is similar to that involved in the increase in vapor pressure of a pure liquid<br />

with increasing temperature, as discussed in Chapter 11 "Liquids". In the case of vapor<br />

pressure, however, it is attractive forces between solvent molecules that are being overcome<br />

by the added thermal energy when the temperature is increased.<br />

13.6 Aggregate Particles in Aqueous Solution<br />

Saylor URL: http://www.saylor.org/books<br />

Saylor.org<br />

1245

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