When a metal of group-1 was dissolved in liquid ammonia, the following observations were obtained: (a) Blue solution was obtained initially. (b) On concentrating the solution, blue colour changed to bronze colour. How do you account for the blue colour of the solution ? Give the name of the product formed on keeping the solution for some time.

When a metal of group-1 was dissolved in liquid ammonia, the following

1.	When a metal of group-1 was dissolved in liquid ammonia, the following observations were obtained: (a) Blue solution was obtained initially. (b) On concentrating the solution, blue colour changed to bronze colour. How do you account for the blue colour of the solution ? Give the name of the product formed on keeping the solution for some time.
Answer» Solution :(a) Alkali metals dissolve in liquid AMMONIA and give BLUE solution because of ammoniated electrons. These electrons ABSORB energy in the visible region of light and IMPART blue colour to the solution. `M+(x+y) NH_(3) to [M(NH_(3))_(x)]^(+) +[(NH_(3))_(y)]^(-)e` (b) In concentrated solution, the blue colour changes to bronze colour due to the formation of clusters of metal ion, on standing, blue solution liberate H, gas with the formation of amide. `M^(+)+e^(-) +NH_(3) to underset("(amide)")(MNH_(2))+(1)/(2) H_(2)`