State which of the following species are amphiprotic and write chemical equations illustrating the amphiprotic character of these species

a) NH3
b)HPO4
c)Br
d)NH4
e)AsO4

1 answer

a) NH3 is amphiprotic because it can act as a proton donor (acid) or acceptor (base).

NH3 + H2O ↔ NH4+ + OH- (acting as a base)
NH3 + H+ ↔ NH4+ (acting as an acid)

b) HPO4 is amphiprotic because it can donate or accept two protons.

HPO42- + H2O ↔ H2PO4- + OH- (acting as a base)
H2PO4- + H+ ↔ H3PO4 (acting as an acid)

c) Br is not amphiprotic as it cannot donate or accept protons.

d) NH4 is not amphiprotic as it can only act as a proton donor (acid).

NH4+ + H2O ↔ H3O+ + NH3 (acting as an acid)

e) AsO4 is not amphiprotic as it can only act as a proton acceptor (base).

AsO43- + H+ ↔ H2AsO4- (acting as a base)