Question #56cc5

1 Answer
Bio
Feb 8, 2016

ZnCl2

Explanation:

In water (or solutions), ZnCl2 dissolves.

ZnCl2(s)→Zn2+(aq)+2Cl−(aq)

The chloride ions do not participate in the following reactions.

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For the sodium hydroxide reaction, the Zn2+ will react with the OH− ions (from NaOH) in the solution.

Zn2+(aq)+2OH−(aq)→Zn(OH)2(s)

Zn(OH)2 is amphoteric, so it can reacts with the excess NaOH.

Zn(OH)2(s)+2OH−(aq)→Zn(OH)2−4(aq)

Zinc hydroxide will dissolve because the ion is normally surrounded by water ligands; when there is excess sodium hydroxide, the hydroxide ions displace the water ligands and the complex will acquire a −2 charge, making it soluble.

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For the ammonia reaction, the NH3 first dissociates in water.

NH3(aq)+H2O(l)⇌NH+4(aq)+OH−(aq)

The Zn2+ will then react with the OH− ions in the solution.

Zn2+(aq)+2OH−(aq)→Zn(OH)2(s)

Zinc hydroxide also dissolves in excess aqueous ammonia to form a colorless, water-soluble ammine complex.

Zn(OH)2(s)+4NH3(aq)→Zn(NH3)2+4(aq)+2OH−(aq)

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The rest of the compounds provided will also dissolve in the solutions, but their hydroxides will precipitate out, rendering them "insoluble".

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