When cobalt chloride is added to pure water, the Co 2+ ions hydrate. The hydrate

Question

When cobalt chloride is added to pure water, the Co2+ ions hydrate. The hydrated form then reacts with the Cl- ions to set up the equilibrium shown here:

Co(H2O)62+ + 4Cl- CoCl42- + 6H2O

(pink) (blue)

Which statement accurately describes the change that the system will undergo if water is added?

A. The color will become more blue.

B. The equilibrium will shift to the right.

C. More water will be produced.

D. More chloride ions will be produced.

E. There will be less of the hydrated cobalt ion at the new equilibrium position.

THe answer is A but I don't know why because i thought its D. can anyone explain why the answer is (A) ?

Explanation / Answer

It quite very simple. If you see the properties of cobalt, you would come to see that when cobalt is hydrated ( cobalt + water), it is pink in color whereas when hydrated cobalt is reacted, it gets converted into anhydrous form and thus its color changes from pink to blue. For clarity, http://simple.wikipedia.org/wiki/Cobalt(II)_chloride

Its answer wont be D because if more chloride ions will yeild, they will react to water molecules to to form HCl in order to get stable oxidation state. But in reality, chloride ions with cobalt has much more stable oxidation state. Try to find out the oxidation state of cl ions in both states. I guess it's clear now.

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