Question
The metallic sodium disolves in liquid ammonia to form a deep blue coloured solution. The deep blue colour is due to formation of :
A.
solvated electron, $$e\left( {N{H_3}} \right)_x^ - $$
B.
solvated atomic sodium, $$Na{\left( {N{H_3}} \right)_y}$$
C.
$$\left( {N{a^ + } + N{a^ - }} \right)$$
D.
$$NaN{H_2} + {H_2}$$
Answer :
solvated electron, $$e\left( {N{H_3}} \right)_x^ - $$
Solution :
The alkali metals dissolve in liquid ammonia without evolution of hydrogen. The metal loses electrons and combine with ammonia molecule.
$$M \to {M^ + }\left( {{\text{in liquid ammonia}}} \right)$$ $$ + {e^ - }\left( {{\text{ammoniated}}} \right)$$
$$M + \left( {x + y} \right)N{H_3} \to $$ $${\left[ {M{{\left( {N{H_3}} \right)}_x}} \right]^ + } + \mathop {{e^ - }{{\left( {N{H_3}} \right)}_y}}\limits_{{\text{Solvated electron }}} $$