Questions 1 Mtaq in dilute solution is light blue When NHs i

Questions 1. Mt(aq) in dilute solution is light blue. When NHs is added the solution becomes tan because of the presence of M(NH3)63 (aq). The equilibrium may be represented as M3+(aq) 6NH3(aq) M(NH3)63t(aq) + Describe what you would expect to SEE if a solution of concentrated KOH were added dropwise and then in excess to the equilibrium system. M(OH)3 is insoluble. Explairn your expected observations in terms of LeChatelier\'s principle.

Solution

When KOH is added dropwise M(OH)3 precipitates out slowly and M3+ is used up in the alternative reaction:

M³⁺(aq) +3OH^- (aq)---->M(OH)3(s)

Thus one of the reactant of the given equilibrium decreases .This shifts the equilibrium to the left (in the reverse direction ) producing more reactant M3+ to compensate for the change.(Le chatlier\'s principle).

M3+(aq) +6NH3(aq) <--->[M(NH3)6 ]³⁺(aq)

This reverse directed reaction takes place until no more OH- is added and a new equilibrium is established .

If KOH is added in excess,then the reaction goes to completion in the reverse direction and all the complex [M(NH3)6 ]³⁺(aq) converts to M3+to precipitate M(OH)3.The color changes from tan to light blue and then precipitate with clear solution.