solubility

Solubility is the maximum amount of solute that a fixed quantity of solvent can dissolve at a particular temperature.

• Solubility isn't fixed for all conditions — for most solids, it increases as temperature rises, which is why hot water can dissolve more baking soda than cold water can.
• Gases behave in the opposite way: their solubility in water generally decreases as temperature rises, which is exactly why cold water holds more life-sustaining dissolved oxygen than warm water does.
• Once a solvent has dissolved its maximum possible amount of solute, the solution is saturated — solubility is really just the specific number that marks where "unsaturated" turns into "saturated."
• Knowing a substance's solubility at different temperatures is exactly the kind of information that lets scientists and cooks alike predict, rather than just observe, how much of something will dissolve.