sblock Elements 1 Question 17
13. Sodium metal on dissolution in liquid ammonia gives a deep blue solution due to the formation of (2019 Main, 10 Jan II)
(a) sodium ammonia complex
(b) sodium ion-ammonia complex
(c) sodamide
(d) ammoniated electrons
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Answer:
Correct Answer: 13. (d)
Solution:
- Sodium metal on dissolution in liquid ammonia gives a deep blue solution due to the formation of ammoniated electrons. The reaction is represented as follows:
$\mathrm{Na}(s)+(x+y) \mathrm{NH} _{3}(l) \longrightarrow \underset{\substack{\left[\mathrm{Ammoniated} \mathrm{Na}^{+} \ \text {or expanded Na}]\right.}}{\left[\mathrm{Na}(\mathrm{NH}) _{2}\right]^{+}}+\underset{\substack{[\mathrm{Ammoniated} \ \text { electrons }]}}{\left[e _{\left(\mathrm{NH} _{3}\right) _{y}}\right]}$
Ammoniated (solvated) electrons show electronic transition in visible region and the solution becomes deep blue coloured.
This deep blue solution also shows the following properties due to the presence of ammoniated electrons.
(i) It is strongly reducing in nature.
(ii) It is paramagnetic.
(iii) It is a good conductor of electricity.
