Simple Distillation

Principle: Separates volatile liquids from non-volatile impurities, or liquids with a large difference in boiling points ($$> 30\text{ K}$$ or $$30^\circ\text{C}$$).

Examples: Ether ($$\text{b.p. } 308\text{ K}$$) and Toluene ($$\text{b.p. } 384\text{ K}$$); Chloroform ($$\text{b.p. } 334\text{ K}$$) and Aniline ($$\text{b.p. } 457\text{ K}$$).

Key Points:

Used to purify substances that are steam volatile and immiscible with water. The mixture boils when the sum of individual vapor pressures equals atmospheric pressure:

$$P_{\text{total}} = P_{\text{water}} + P_{\text{organic compound}} = P_{\text{atm}}$$

Condition: Because $$P_{\text{total}} = P_{\text{atm}}$$, the mixture boils at a temperature lower than the boiling point of pure water ($$< 373\text{ K}$$).

Examples: Aniline, Nitrobenzene, Essential oils, O-nitrophenol.