Question

Discuss briefly two physical and three chemical properties of ethanol. [5 MARKS]

Answer 1

Physical properties: 2 Mark
Chemical properties: 3 Mark

1. Physical properties of ethanol-
Ethanol is a liquid at room temperature.
Ethanol is water soluble in all proportions.

2. Chemical properties of ethanol-

• Ethanol exhibits acidic behavior because it reacts with sodium evolving hydrogen gas and salt sodium ethoxide is also produced.
  $2\text{Na}+2{\text{CH}}_3{\text{CH}}_2\text{OH}\to 2{\text{CH}}_3\text{CHONa}+{\text{H}}_2$
  
• Heating ethanol at 443 K with excess concentrated sulphuric acid results in the dehydration of ethanol to give ethene.
  ${\text{CH}}_3{\text{CH}}_2\text{OH}+{\text{Conc.H}}_2{\text{SO}}_4\to {\text{CH}}_2={\text{CH}}_2+{\text{H}}_2\text{O}$
  
  Concentrated sulphuric acid can be regarded as a dehydrating agent which removes water from ethanol.
  
• Ethanol ${\text{CH}}_3{\text{CH}}_2\text{OH}$ when treated with acidified ${\text{K}}_2{\text{Cr}}_2{\text{O}}_7$ + Heat or alkaline ${\text{KMnO}}_4$ + heat, it gets oxidized to ethanoic acid ${\text{CH}}_3\text{COOH}$.