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
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)