[Professor]

Hi there!

Today I came across a question which says:

'Which salt can be prepared by an acid-alkali titration?'

a) ammonium nitrate
b) copper(II) nitrate
c) iron(II) nitrate
d) zinc nitrate


I chose (d) zinc nitrate but the answer is (a) ammonium nitrate. I don't understand why it is so. I know that both (a) and (d) are amphoteric products but I just don't understand why the answer is (a). Could someone explain to me? Thanks a lot. 

[xiankai]

nitrate can come from nitric acid, but zinc...? zinc oxide and zinc hydroxide are both insoluble and count as bases but not alkalis. same goes for copper and iron oxide/hydroxides. the ammonium ion however, comes from aqueous ammonia.

by the way, what do you mean by amphoteric products?

[Professor]

nitrate can come from nitric acid, but zinc...? zinc oxide and zinc hydroxide are both insoluble and count as bases but not alkalis. same goes for copper and iron oxide/hydroxides. the ammonium ion however, comes from aqueous ammonia.

by the way, what do you mean by amphoteric products?

Amphoteric products mean that the products have the characteristics of an acid and a base and capable of reacting chemically either as an acid or a base.


How you know that zinc oxide and zinc hydroxide are insoluble?