1. Tardigrade
  2. Question
  3. Chemistry
  4. When alkaline earth metals dissolve in ammonia, they form coloured solution like alkali metals. Which of the following observations regarding the reaction are correct ? (i) Dilute solutions are bright blue in colour due to solvated electrons. (ii) These solutions decompose to form amides and hydrogen. (iii) From this solution the ammoniates [M(NH3)6]2+ can be recovered by evaporation.

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Q. When alkaline earth metals dissolve in ammonia, they form coloured solution like alkali metals. Which of the following observations regarding the reaction are correct ?
(i) Dilute solutions are bright blue in colour due to solvated electrons.
(ii) These solutions decompose to form amides and hydrogen.
(iii) From this solution the ammoniates $[M(NH_3)_6]^{2+}$ can be recovered by evaporation.

The s-Block Elements

Solution:

All the observations are correct.
$M \rightarrow M^{3+} +2e^-$
$2NH_3+2e^- \rightarrow 2NH^-_2 +H_2$
$M^{2+}+2NH^-_2 \rightarrow M(NH_2)_2 \xrightarrow{\text{eyporation}} [M(NH_3)_6]^{2+}$
$[M(NH_3)_6]^{2+} \to M(NH_2)_2 + 4NH_3 + H_2$