Question

The Alkali metals dissolve in liquid $N{H}_3$. It is observed that

• A. The dilute solutions are blue and the colour changes to bronze with increasing concentration.
• B. The blue colour is due to solvated electrons
• C. The blue solutions are paramagnetic & reducing agents
• D. All the above facts are correct

Answer 1

The correct option is D

All the above facts are correct

Alkali metals easily dissolve in liquid ammonia to form blue coloured solution in dilution due to the ionisation of alkali metal atom into ammoniated metal ion and ammoniated electron.

$M\left(s\right)+(x+y)N{H}_3\to \left[M\right(N{H}_3{)}_x{]}^{+}+\left[e^{-}\right(N{H}_3{)}_y{]}^{-}$

Ammoniated metal ion Ammoniated electron

The blue colour is due to the ammoniated electrons which absorb energy corresponding to the red region of the visible light and this blue colour turns to bronze on increasing the concentration as the pairing process (Pairing of species available in the solution) takes place. These solutions are paramagnetic due to the presence of unpaired electrons and are reducing in nature.