Evaporation to Dryness v.s Simple Distillation
(Concepts of Boiling Point) 

Separation of Solutions using Differences in Boiling Points

Both evaporation to dryness and simple distillation are separation techniques that are used to separate solutions (mixture of soluble solid and liquid) by the differences in boiling points between the solute and solvent

• The solvent has a lower boiling point than the solute will vapourise and turn into a gas. 

• The solute has a higher boiling point than the solvent and will be left behind as a residue (solid). 

• E.g., water has a boiling point of 100 °C, while sodium chloride salt has a boiling point of 1465°C. Water is boiled away, while sodium chloride is left behind as a residue 

For evaporation to dryness (only the soluble solid is collected): 

• The soluble solid is left behind as residue when the solvent has boiled away by strong heating. 

• The solvent is lost and is unable to be collected. 

For simple distillation (both the soluble solid and liquid is collected): 

• The soluble solid is left behind in the distillation flask as the residue 

• The solvent is boiled in the distillation, where the vapour of the solvent is condensed in the condenser, and is collected as distillate