Question

The conjugate acid and conjugate base of bicarbonate ion, HPO 4 2 –, are, respectively:

a.

H3O+ and OH–

b.

PO43– and OH–

c.

H2PO4- and PO43–

d.

H3O+ and PO42–

e.

H3PO4 and OH–

Answer 1

First of all ,the options you have given are not matching with the question. The answer for the conjugate acid and conjugate base of bicarbonate ion is not here in any one of options.

Coming to the question, the bicarbonate ion is a base have -1 charge i.e; HCO₃^- and this is an amphiprotic ion which can act as both acid and base by losing or gaining proton respectively.

The addition of proton to a base yields conjugate acid. so, here

HCO₃^-   + H⁺ ----------> H₂CO₃

(conjugate acid of bicarbonate ion)

The removal of a proton form a acid gives conjugate base. so, for bicarbonate ion here acting like an acid

HCO₃^- ----------> CO₃^2- + H⁺

(conjugate base of bicarbonate ion)

And also remember that these all are equilibrium reactions , and not one way reactions.

Now coming to the HPO₄^2- ion, this also acts like amphiprotic as i stated above for bicarbonate ion.

The conjugate base of this species is given by the removal of proton ,

HPO₄^2- ---------->    PO₄^3- +    H⁺

(conjugate base of HPO₄^2-)

The conjugate acid is given by addition of a proton,

HPO₄^2- + H⁺ ----------> H₂PO₄^-

(conjugate acid of HPO₄^2-)