Question

Zn2+ and Al3+ are amphoteric. Demonstrate

howAl(OH)3(s) and Zn(OH)2(S) react in
anamphoteric manner (show balanced chemical equations),

Write balanced chemical reactions for the following:
a. NH3 was added to Cu2+ and
toFe3+ and water.
b. NH3 was added to Zn2+ and
toAl3+ and water.

Answer 1

Step-by-step explanation:

1) Amphoteric substances can react both like an acid or a base depending if they are in presence of a base or an acid.

Zinc hydroxide (Zn(OH)2):

In acid:
`Zn(OH)_2 + 2 HCl \longrightarrow ZnCl_2 + 2 H_2O`

In base:
`Zn(OH)_2 + 2 NaOH \longrightarrow Na_2[Zn(OH)_4]`

Aluminium hydroxide (Al(OH)3)

In acid:
`Al(OH)_3 + 3 HCl \longrightarrow AlCl_3 + 3 H_2O`

In base:
`Al(OH)_3 + NaOH \longrightarrow Na[Al(OH)_4]`

2) Reactions

a)
`2 NH_3 + Cu^(2+) + 2 H_2O \longrightarrow 2 NH_4^+ + Cu(OH)_2`

`3 NH_3 + Fe^(3+) + 3 H_2O \longrightarrow 3 NH_4^+ + Fe(OH)_3`

b)
`2 NH_3 + Zn^(2+) + 2 H_2O \longrightarrow 2 NH_4^+ + Zn(OH)_2`

`3 NH_3 + Al^(3+) + 3 H_2O \longrightarrow 3 NH_4^+ + Al(OH)_3`