This video explains how evaporation and crystallisation work together to recover a dissolved solid from a solution, and why evaporation happens at the surface of a liquid even below its boiling point. You'll see the practical setup, understand the particle-level explanation, and learn when to stop heating to produce crystals rather than a dry powder.

What You Will Learn

01:10What evaporation is at a particle level and why it occurs below a liquid's boiling point.

02:12How the distribution of particle energies determines the rate of evaporation.

03:18What the key differences between boiling and evaporation are.

05:02How increasing surface area affects the rate of evaporation.

06:20What an evaporating basin is and how it is used in a standard evaporation practical.

07:07Why a water bath is sometimes used instead of direct heating with a Bunsen burner.

08:03What crystallisation is and when to stop evaporating to produce well-formed crystals.

10:11How a rotary evaporator works and why it is used when the solute is heat-sensitive.