Question

The alkali metals dissolve in ammonia to give a deep blue solution which is conducting in nature.

$M + (x + y)NH_{3} \rightarrow \lbrack M(NH_{3})_{x}\rbrack^{2 +} + 2\lbrack e\left( NH_{3} \right)_{y}\rbrack^{-}$

Which of the following is not true about the solutions of alkali metals in liquid ammonia?

• A. The blue colour is due to ammoniated electron.
• B. The solution is paramagnetic.
• C. The blue colour changes to brown on standing.
• D. In concentrated solution blue colour changes to bronze and becomes diamagnetic.

Answer 1

Answer: (C)

The blue colour changes to brown on standing.

Answer 2

: On standing it slowly liberates hydrogen resulting in formation of amide.

$M_{(am)}^{+} + e_{(am)}^{-} + NH_{3(l)} \rightarrow MNH_{2(am)} + \frac{1}{2}H_{2(g)}$

Where ‘am’ denotes solution in ammonia.