Which statement correctly describes solubility changes with temperature for solids and gases?

• A. Solubility of solids increases with temperature; solubility of gases decreases with temperature.
• B. Solubility of solids decreases with temperature; solubility of gases increases with temperature.
• C. Both solids and gases solubility increase with temperature.
• D. Temperature has no effect on solubility.

Answer: (A)

Temperature affects dissolution differently for solids and gases. For most solids, dissolving requires breaking the solid’s lattice and forming interactions with the solvent, a process that is often endothermic. Adding heat helps overcome the lattice energy and promotes solvation, so the solid becomes more soluble as temperature rises (and entropy increase with dissolution also favors the process at higher temperatures). For gases, dissolving in a liquid is usually exothermic: gas molecules interact with the solvent and release heat as they are solvated. Increasing temperature supplies energy to push the system back toward the gas phase, so the amount of gas that can stay dissolved decreases. This combination—solids more soluble with higher temperature and gases less soluble with higher temperature—matches the described statement.