Question

With the help of a labelled diagram, describe the method of separating ammonium chloride from a mixture of ammonium chloride and common salt. Mention the difference in the properties of ammonium chloride and sodium chloride which has made this separation possible.

Answer 1

• There are many substances that are converted into a gas from a solid when heated and converted from gas to solid when cooled without converting into liquid. Such substances are known as sublime.
• For example – ammonium chloride, naphthalene balls, camphor, etc. Therefore, the mixture of one sublime and another substance can be separated using the method of sublimation.
• The mixture of ammonium chloride and common salt can be separated out using the process of sublimation.
• For this, the mixture is heated in a China dish. The China dish is covered by an inverted funnel. Cotton is used for plugging the opening of the funnel.
• After heating, ammonium chloride is converted into vapor and gets deposited over the inner surface of a funnel; due to cooling. This leaves the common salt in China dishes.
• Ammonium chloride can be taken out by scratching from the inner wall of the funnel.
  

Separation of ammonium chloride and salt by sublimation

• The process of sublimation is used to separate that component of a solid-solid mixture that sublimes on heating. Hence the property of ammonium chloride to sublime has made this separation possible.