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Bonding and Gas Solubilities


Consider the following data concerning the solubility of two gaseous compounds, ammonia and hydrogen chloride, at various temperatures.

Molar Solubility of Gaseous Ammonia and Hydrogen Chloride as a Function of Temperature

Temperature, $^{\circ}$C NH$_{3(g)}$ HCl$_{(g)}$
0 52.9 M 22.5 M
20 14.8 M 12.3 M
60 3.5 M 15.3 M

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The molar solubility of ammonia gas is significantly greater than that of hydrogen chloride at 0ºC, but its solubility drops off dramatically with increasing temperature.

By comparison, raising the temperature causes the molar solubility of hydrogen chloride to decrease at first, but as the temperature gets even higher, the molar solubility of $HCl$ begins to increase.

Which of the following BEST explains the difference in solubilities at 0ºC?


Ammonia molecules are smaller than hydrogen chloride molecules, so they fit into the spaces between water molecules more readily.


Ammonia is able to hydrogen bond to water, but hydrogen chloride is not.


Ammonia ionizes less in water and so is able to dissolve better.


Hydrogen chloride gas is less dense than ammonia gas, so it tends to escape from solution more readily.