Question

The alkali metals dissolve in liquid $N{H}_3$, it is found that:

• A. the dilute solution is blue but the color changes to bronze with increasing concentration.
• B. the blue color is due to presence of solvated electrons.
• C. the blue solutions are paramagnetic but the bronze colored solutions are diamagnetic.
• D. all the facts given above are found.

Answer 1

The correct option is D all the facts given above are found.

All alkali metals dissolve in anhydrous liquid ammonia to give blue colour solution.

It is the ammoniated electron which is responsible for the blue colour of the solution, and the electrical conductivity is due to ammoniated cation, $\left[M\right(N{H}_3{)}_x{]}^{+}$ as well as the ammoniated electron, $\left[e\right(N{H}_3{)}_y{]}^{-}$, values of x and y depend on the extent of solvation by $N{H}_3$.

Dilute solutions are paramagnetic due to free ammoniated electrons.

As we increase concentration, association of solvated electrons get started and paramagnetism decreases and colour changes to bronze.

Hence, the correct option is $\text{D}$