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.

Question

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. (A) Only (i) and (ii) (B) Only (i), (ii) and (iii) (C) Only (ii) and (iii) (D) Only (i)

Tardigrade Admin · Accepted Answer

All the observations are correct. M arrow M3+ +2e- 2NH3+2e- arrow 2NH-2 +H2 M2++2NH-2 arrow M(NH2)2 xrightarrow texteyporation [M(NH3)6]2+ [M(NH3)6]2+ → M(NH2)2 + 4NH3 + H2

Only (i) and (ii)

Only (i), (ii) and (iii)

Only (ii) and (iii)

Only (i)

All the observations are correct. M→M3++2e− 2NH3​+2e−→2NH2−​+H2​ M2++2NH2−​→M(NH2​)2​eyporation​[M(NH3​)6​]2+ [M(NH3​)6​]2+→M(NH2​)2​+4NH3​+H2​

All the observations are correct.
$M \to M^{3 +} + 2 e^{-}$
$2 N H_{3} + 2 e^{-} \to 2 N H_{2}^{-} + H_{2}$
$M^{2 +} + 2 N H_{2}^{-} \to M (N H_{2})_{2} eyporation [M (N H_{3})_{6}]^{2 +}$
$[M (N H_{3})_{6}]^{2 +} \to M (N H_{2})_{2} + 4 N H_{3} + H_{2}$