What are some common mistakes students make with saturated solutions?

1 Answer
Aug 8, 2015

Answer:

The 1 fatal error is to state that " a saturated solution holds a maximum amount of solute ". This is would be gleefully/regretfully (?) pounced upon by any examiner and marked wrong.

Explanation:

Saturation describes an equilibrium condition, namely "that the solution holds the same amount of solute that would be in equilibrium with undissolved solute" . As with any equilibrium, a temperature is usually specified, because a hot solution can normally hold more than solute than can a cold one.

Supersaturated solutions hold a greater amount of solute than would be in equilibrium with undissolved solute. You have probably seen some spectacular demonstrations of supersaturation after such a solution has had a seed crystal deposited, and masses of solute deposit (of course, after such an event the solution is once again saturated inasmuch as the solution has returned to equilibrium).

Why am I stressing this? Because questions regarding saturation are routinely poorly done at A levels, whereas a little care with definitions would give easy marks.