The effect of temperature on solubility depends on the type of solute:
1. Solid solutes in liquids
- Usually, solubility increases with temperature.
- When a solid dissolves, heat is often absorbed (endothermic process). Adding more heat allows more solute particles to break free and dissolve.
- Example: More sugar dissolves in hot tea than in cold tea.
- Exception: Some salts (like calcium sulfate or cerium sulfate) show decreased solubility at higher temperatures if the dissolution is exothermic.
2. Gaseous solutes in liquids
- Solubility decreases with increasing temperature.
- Dissolving a gas in a liquid is usually exothermic. Adding heat gives gas molecules more energy to escape from the liquid into the air.
- Example: Cold soda holds more carbon dioxide and fizzes less, while warm soda loses gas quickly when opened.
Summary:
- Solids in liquids → Solubility generally increases with temperature (except some salts).
- Gases in liquids → Solubility decreases with temperature.