Question

C. Complex Ion Equilibria
5.Explain the color change that occurred when water was added in Step 2 of the procedure. 



6.Explain the color change that occurred when the diluted solution was heated. i.How did increasing the temperature affect the value of Kc? 
ii.What is the sign of ΔH in Reaction 7? 
Co(H2O)6^2+ (aq) + 4Cl- (aq) <——> CoCl4^2+ (aq) + 6H2O

Answer 1

Reaction, [Colfo) 6 3 + 4ci (Pink) [Coclyt + 6H2O; Blue) BH=tve forward Reaction is Endothermic

5. Pink

According Le chatelier principle, when water is added, equilibrium will try to minimise the impact of addition of water. since water is already present in product side, so equilibrium will shift in reactant direction. so we will observe pink colour.

6. Blue

On increasing temperature, equilibrium tries to minimise the effect of increase in temperature. So, it shifts in endothermic direction. since forward direction is endothermic direction, so colour observed would be blue.

i) Since on increasing temperature equilibrium shifts in forward direction .so, Kc value also increases.

ii) delta H = +ve

If it is a endothermic reaction