Glacial acetic acid is obtained by

Options

A. chemically separaing acetic acid
B. treating vinegar with dehydrating agents
C. crystallising, separaing and melting acetic acid
D. distilling vinegar

Answer

A

Explanation

The glacial acetic acid is made by fractional distillation. The pyroligneous acid is neutralised with milk of lime, methyl alcohol and acetone are distilled off- the solution of calcium acetate is then evaporated to dryness. The dry calcium acetate is distilled with concentrated sulphuric acid-the distillate contain about 50% of acetic acid. `(CH_(3)CO O)_(2)Ca+H_(2)SO_(4)=CaSO_(4)+2CH_(3)CO OH`. This is neutralised with caustic soda, and the solution is evaporated to dryness. the dry sodium acetate thus formed on distillation with concentrated `H_(2)SO_(4)` gives a distillate of glacial acetic acid. `2CH_(3)COONa+H_(2)SO_(4)=2CH_(3)COOH+Na_(2)SO_(4)`. Any water still present is removed by cooling the acid in ice, when pure acetic acid alone solidifies as colourless ice like (glacial) mass, and hence the name glacial acetic acid.