Question

In Epsom salt, the number of molecules of water directly coordinated with $M{{g}^{2+}}$ ion are:
(a) 2
(b) 4
(c) 6
(d) 7

Answer 1

Hint: Epsom salt is a compound of an element that belongs to group 2 of the s-block. Epsom salt is a heptahydrate salt. The atomic number of the element is 12.

Complete step by step solution:
Magnesium sulfate is the chemical name of Epsom salt. The formula of magnesium sulfate is $MgS{{O}_{4}}$. The oxidation number of magnesium in magnesium sulfate is $+2$.
More specifically we can say that Epsom salt is the heptahydrate form of magnesium sulfate. So the formula of heptahydrate magnesium sulfate is $MgS{{O}_{4}}.7{{H}_{2}}O$. It is used as a household chemical. It has many traditional uses, which include bath salt. The bath salt is used to enhance the cleaning purpose.
But actually, the Epsom salt is written as $[Mg{{({{H}_{2}}O)}_{6}}]({{H}_{2}}O)(S{{O}_{4}})$ which means that 6 molecules of water are directly coordinated to a magnesium ion.
The molecular mass of Epsom salt is $246.47\text{ g/mol}$. It is a white crystalline solid. It is an odourless compound. The density of Epsom salt is $1.68\text{ g/c}{{\text{m}}^{3}}$.
The melting point of Epsom salt is ${{150}^{\circ }}C$, it means that the Epsom salt decomposes at ${{150}^{\circ }}C$.
The solubility of Epsom salt in water is 113g / 100 mL at ${{20}^{\circ }}C$.
The name of Epsom salt originated from the town Epsom in Surrey, England because it was discovered there.
Epsom salt is used for the treatment of many diseases like constipation, insomnia, and fibromyalgia.
The formation of magnesium and sulfate ions occurs when Epsom salt is dissolved in water. This water can be directly applied to the skin for direct absorption of these ions, which is used for body functioning.

Therefore, the correct answer is an option (C) 6.

Note: Don't get confused between 7 and 6 because the chemical formula of Epsom salt has 7 molecules of water. Since the Epsom salt can be applied to the skin directly, therefore, it is available as cosmetics. The Epsom salt is also taken as a magnesium supplement or as a laxative.