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Offline xstrae

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Simple question
« on: November 10, 2006, 02:18:32 PM »
Hi, This might sound really basic but my teacher and myself had a long discussion on this. So I thought I will get your opinion on it.

Why is Zn(OH)2 amphoteric while NaOH is basic?

thanks.

Offline DevaDevil

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Re: Simple question
« Reply #1 on: November 10, 2006, 04:05:37 PM »
Because Zn(OH)2 can either release the OH--ions and form Zn2+(aq) + OH-(aq), or take OH- from the solution forming a complex: Zn[(OH)4]2-

In acids, it will react following the first hence increasing the pH, in bases it will follow the 2nd, hence lowering the pH

NaOH will not form complexes, so can only react as a base.

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