Question

In the reaction :

M + (x+y)NH₃ ____{> [M(NH3)x]}+ _{+. [e(NH3)y]^-}

_{^{{Where M is alkali metal } what is the meaning of 'x' and 'y'?}}

Answer 1

Here the x, y are meaning that there are total of x+y molecules of ammonia out of which x molecules are associating with metal to form the compound.
M + x NH3 --> [M(NH3)x]^+
and the rest y molecules of ammonia is combining with electrons released by sodium to form ammoniated electrons
yNH3 +e --> [e(NH3)y]^-
This are approximate values for ammonia combining with metal and electron because there is no fixed ratio in this reaction.