CSSA Multiple choice (1 Viewer)

[kaz1]

CSSA 2002

7. Swimming pools are sterilised by adding calcium hypochlorite, Ca(OCl)₂, or sodium hypochlorite, NaOCl.

The equilibrium involved is:

OCl^-(aq) + H₂O(l) <---> HOCl(aq) + OH^-(aq)

The species that is best at destroying bacteria and at resisting decompisition by sunlight is HOCl.

Identify the reation conditions that will favour the formation of HOCl.

(A) adding NaOH
(B) adding HCl
(C) adding water
(D) both (B) and (C)

The answer is B but I said D. Can someone explain why adding water will not move the equilibrium to the right?

 

[kaz1]

Bump.

 

[rufous]

Because the reaction is taking place in an aqueous system (water is the solvent) its concentration is very high and changes very little by adding any more water and so its effect is quite negligible. Any changes in the other components is quite significant as ther is not much of them present in the first place. Hope this helps .......Cheers