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Solubility

Dissolving depends on the substance, the solvent, temperature and sometimes pressure.

What happens

A solution forms when interactions between solute and solvent make dispersed particles thermodynamically favourable under the conditions. Different substances can therefore have very different solubilities in the same solvent.

For many solid solutes in water, solubility increases with temperature, but this is not a universal rule. Each solute-solvent pair has its own behaviour.

What changes the process

Gases often become less soluble in liquids as temperature rises. Increasing the partial pressure of a gas above a liquid generally increases how much of that gas dissolves.

Why it matters

A saturated solution is at equilibrium with undissolved solute under the stated conditions. Adding more solute then does not simply force an unlimited amount into solution.

Go one step further

A useful way to understand this phenomenon is to separate the driving force from the visible result. Temperature, pressure, concentration, surface area and the nature of the materials can each change the rate or the final state. In real systems, several of these factors often act at the same time.

That is why the same phenomenon can look different in a laboratory, in the kitchen or outdoors. The underlying chemistry or physics stays the same, but the conditions change the balance.