Question

A solution of calcium in liquid ammonia when evaporated to dryness gives a complex:
(A) Pure Ca
(B) ${{[Ca{{(N{{H}_{3}})}_{x}}]}^{2+}}$
(C) ${{[Ca{{(N{{H}_{3}})}_{6}}]}^{2+}}$
(D) $Ca{{(N{{H}_{3}})}_{6}}$

Answer 1

Hint: The group 2 elements are beryllium (Be), Magnesium (Mg), Calcium (Ca), strontium (Sr), Barium (Ba), and Radium (Ra) and these metals are known as alkaline earth metals (except Beryllium) which are followed by alkali metals in s-block elements. These metals exhibit various chemical properties with halogens, liquid ammonia, air, and water.

Complete step by step answer:
The alkaline earth metals are less reactive than the alkali metals which are Group IA elements in the periodic table. In groups, these alkaline earth metals reactivity increases on going down.
The chemical properties of alkali earth metals:
(i) Reactivity towards air and water
(ii) Reactivity towards the halogens
(iii) Reactivity towards acids
(iv) Reducing nature
(v) Solutions in liquid ammonia
The given element Calcium (Ca) belongs to alkali earth metals. This metal dissolves in liquid ammonia which gives deep blue-black solutions forming ammoniated ions like alkali metals.
The general equation for alkaline earth metals when dissolved in liquid ammonia solution,
$M+(x+y)N{{H}_{3}}\to {{[M{{(N{{H}_{3}})}_{x}}]}^{2+}}+2{{[e{{(N{{H}_{3}})}_{y}}]}^{-}}$

Where M = alkaline earth metals,
For a solution of calcium in liquid ammonia when evaporated to dryness gives a complex is:
$Ca{{(N{{H}_{3}})}_{6}}$
So, the correct answer is “Option D”.

Note: The complex which is formed when calcium dissolved in liquid ammonia obtained calcium with ammonia complex, which calcium has coordination number 6. The six ammonia acts as a ligand in this complex which is to donate electron pairs to Ca and form coordination covalent bonds with calcium. This compound is known as coordination complex compounds.