Question

Ammonium chloride is separated from a mixture of sodium chloride and ammonium chloride by the process of:

Answer 1

Hint: If you have ever seen the balls of Naphthalene left in the open then you won’t find them in the place as it has converted into the vapours. Same happens with the Ethanol or Acetone, these chemicals disappear into the air by changing their states.

Complete answer:
- Sublimation is a process by which the solid changes into the vapour directly without undergoing the intermediated phase of liquid. This is possible by exposing the solid to a specific temperature and pressure. It is different for different molecules.
- When the mixture of Ammonium chloride and Sodium chloride is heated then, Ammonium chloride changes its state from solid to vapour while Sodium chloride cannot. The vapours of Ammonium chloride are then condensed on a cold surface and Sodium Chloride is left behind.
- The process of Sublimation is an endothermic process as when the solid is directly heated to a certain temperature then some of the molecules gain much kinetic energy which excites their electrons and hence, they break the intermolecular forces which were binding them and they directly get converted to vapours.

Note: The process of Sublimation takes place below the Triple point of the gases. The triple point is known as where the three states of matter i.e. solid, liquid and gas exist together.