Question

Potash (potassium carbonate) is used as a fertilizer. It is also known as:
(a)- Azo compounds
(b)- Oil of vitriol
(c)- Pearl ash
(d)- Glauber’s salt

Answer 1

Hint: Azo compounds are those which are joined by two nitrogen atoms. Oil of vitriol is a mineral acid of the sulfur element. Pearl ash is the compound of potassium. Glauber’s salt is a salt of sodium element.

Complete step by step answer:
Potassium carbonate is an inorganic compound or it is a salt of potassium element. It has a formula ${{K}_{2}}C{{O}_{3}}$.
It is a white salt and it is soluble in water.
It is known as potash, as it is soluble in water it is used as a fertilizer.
Every year 90 million tonnes of potash are produced in which most of it is used as a fertilizer.
Soap and glasses are usually produced from potassium carbonate.
The molar mass of potassium carbonate is $138.205\text{ g mo}{{\text{l}}^{-1}}$

It is a hygroscopic solid. The solubility of potassium carbonate in water is $112\text{ g/ 100 g}$at${{20}^{\circ }}C$.
The refined form of potassium carbonate is called pearl ash or also called salts of tartar.
Early, pearl ash was produced from baking potash in a kiln to remove the impurities. When the impurities are removed, a fine white powder is left, called pearl ash.
There are 2 methods of production of potassium carbonate:

(i)- From potassium hydroxide: When potassium hydroxide is reacted with carbon dioxide, potash is formed. The reaction is:
$2KOH+C{{O}_{2}}\to {{K}_{2}}C{{O}_{3}}+{{H}_{2}}O$

(ii)-From potassium bicarbonate: When potassium bicarbonate is calcined i.e. heated in a limited supply of air, we get potassium carbonate. The reaction is:
$2KHC{{O}_{3}}\to {{K}_{2}}C{{O}_{3}}+{{H}_{2}}O+C{{O}_{2}}$

So, the correct answer is “Option C”.

Note: Potassium carbonate is also used in a mild drying agent, it is also an ingredient in the formation of grass jelly. It is used to balance the pH by reducing the acidity of the cocoa beans, which is used to make cocoa powder.