Question

What is the formula of Potash alum?
a.$KAl{ ({ SO }_{ 4 }) }_{ 2 }.12{ H }_{ 2 }O$
b.$KAl{ ({ SO }_{ 4 }) }_{ 3 }.12{ H }_{ 2 }O$
c.$KAl{ ({ SO }_{ 4 }) }_{ 3 }.15{ H }_{ 2 }O$
d.$KAl{ ({ SO }_{ 4 }) }_{ 3 }.2{ H }_{ 2 }O$

Answer 1

Hint: Just check which formula satisfies all the valencies for each atom and try to recall chemical formulas related to Alums.

Complete step by step answer:
Potassium alum, potash alum, or potassium aluminium sulfate is a chemical compound. Potash Alum is also known as potassium aluminium sulphate dodecahydrate.
Potassium aluminium sulfate is a metal sulfate composed of potassium, aluminium and sulfate ions in the ratio 1:1:2.
The compound is the most important member of the generic class of compounds called alums, and is often called simply alum. It is also commonly referred to as ‘fitkari.’
The chemical formula of Potash alum is $KAl{ ({ SO }_{ 4 }) }_{ 2 }.12{ H }_{ 2 }O$
Correct option is A.

Additional information: Potassium alum is commonly used in water purification, leather tanning, dyeing, fireproof textiles, and baking powder. It also has cosmetic uses as a deodorant, as an aftershave treatment and as a styptic for minor bleeding from shaving. Potassium alum is formed by large, transparent crystals that are used in different products like food or drugs as a buffer, neutralizing or forming agent.

Note: IUPAC Name of Potash Alum - Aluminium potassium sulfate dodecahydrate