# Equilibrium of zinc ion with ammonia

In my chemistry lab, we are testing the amphoteric properties of this metal. I understand zink can react with an acid or a base to form different compounds in solution based on pH. In one part of the experiment we are testing when ammonia in added gradually to $$\ce{Zn(OH)2(s)}$$ if it redissolves as $$\ce{Zn(OH4)^2-}$$ or if it redissolves as $$\ce{Zn(NH3)4^2+}$$. We are also testing the solution with indicators. So I’m assuming we are using the indicators to determine if there is a pH change because if there wasn’t, the complex ion $$\ce{Zn(NH3)4^2+}$$ would be using up all the weak base for this formation and none of it (or very little of it) would be able to act in solution and deprotonate water and generate $$\ce{OH-}$$?

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• HINT - To figure out which reaction would cause the most pH change edit the question to include the two chemical reactions that can occur when the zinc hydroxide dissolves. – MaxW Apr 7 at 21:58