Humber Admissions Practice Test

Which condition decreases the solubility of gases in a solution?

1. Increased temperature

2. Increased pressure

3. Decreased pressure

4. Decreased concentration of solutes

The correct answer is: Increased temperature

The solubility of gases in a solution is primarily influenced by temperature and pressure. When the temperature of a solution increases, the kinetic energy of gas molecules also increases, leading to more frequent collisions with the surface of the solution. This increased kinetic energy allows gas molecules to escape from the solution more readily, thereby reducing the overall solubility of gas in that solution. This phenomenon is a direct consequence of the relationship between temperature and solubility; as temperature rises, less gas can remain dissolved. In contrast, increasing pressure generally increases gas solubility because it pushes more gas molecules into the solution. Similarly, decreasing pressure leads to less gas being able to stay dissolved. The concentration of solutes in a solution generally pertains to the solubility of solutes themselves, which does not directly affect gas solubility in the same manner that temperature and pressure do. Thus, the understanding of solubility dynamics highlights why an increase in temperature leads to a decrease in gas solubility.