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If I raise the temperature of a solution of a gas in a liquid solvent, why won't the solubility increase?
Increasing the pressure will increase the solubility, but increasing the pressure doesn't mean increasing the temperature? What is wrong with this argument?
A gas has bigger entropy when it's free, than in a solution. By increasing the temperature the molecules have bigger energy and they tend to be in a state with more freedom. Therefore, the solubility would decrease.
When a gas dissolves in a liquid, bonds are formed between the gas particles and the liquid particles. The formation of these bonds liberates energy. Increasing the temperature of the solution will shift the equilbrium backwards. Hence less gas can dissolve and solubility decreases.
In reference to Henry's Law,
"At a constant temperature, the amount of a given gas that dissolves in a given type and volume of liquid is directly proportional to the partial pressure of that gas in equilibrium with that liquid."
Thus, increasing partial pressure of gas above the liquid increases solubility of gas, which does NOT mean that temperature of the solution is increasing. There is a distinction to be made between the dynamics of the solution and the gas above the solution.
