Question

Molecular formula of Glauber’s salt is:
$
  {\text{A}}{\text{. MgS}}{{\text{O}}_4}.{\text{7}}{{\text{H}}_2}{\text{O}} \\
  {\text{B}}{\text{. CuS}}{{\text{O}}_4}.5{{\text{H}}_2}{\text{O}} \\
  {\text{C}}{\text{. N}}{{\text{a}}_2}{\text{S}}{{\text{O}}_4}.10{{\text{H}}_2}{\text{O}} \\
  {\text{D}}{\text{. FeS}}{{\text{O}}_4}.7{{\text{H}}_2}{\text{O}} \\
$

Answer 1

Hint: To determine the molecular formula of Glauber's salt, we refer to its common name and its chemical name. We figure out its components.

Complete step by step answer:
We know, the common name of Glauber's salt is sodium sulfate deca-hydrate and its formula is given by ${\text{N}}{{\text{a}}_2}{\text{S}}{{\text{O}}_4}.10{{\text{H}}_2}{\text{O}}$, it is generally white or colorless and occurs as monoclinic crystals.
From its common name we can say that it is the deca-hydrate form of sodium sulphate, i.e. ten water molecules are attached to the sodium sulphate molecule resulting in this salt.
When this is exposed to dry air it effloresces (ignites with a glow), forming powdery anhydrous sodium sulfate.
Johann Glauber was the first to produce the salt (from Hungarian spring waters), it was named after him.
So, the correct answer is “Option C”.

Note: In order to answer this type of question the key is to look at the chemical name of the compound, it more or less gives away the molecular formula.
Glauber's salt, the decahydrate, is used as a medicine or laxative. It is used for the removal of certain drugs such as paracetamol (acetaminophen) from the body, for example, after an overdose. In 1953, sodium sulfate was proposed for heat storage in passive solar heating systems as it is anhydrous, its water molecules absorb heat.