Separation methods explained

Choose an appropriate method and track where each substance ends up.

Start with the desired product

A filter retains undissolved solid particles. Dissolved salt passes through an ordinary filter with the water. During evaporation the solvent leaves as vapour; it is not automatically collected.

Properties make the difference

Distillation uses differences in volatility and collects vapour after cooling. Extraction uses differences in solubility. Adsorption binds substances to a surface. Settling uses particles sinking under suitable conditions.

Worked example

You have sand, dissolved salt and water. You want to recover dry salt.

Filter: sand remains as residue, while salt solution passes through as filtrate.
Evaporate the filtrate to recover the salt.

Want to collect water as well? Choose distillation after filtration.