Question

What is the conjugate acid of each of the following bases? Write the equilibrium reactions in aqueous solution for each base.
1) Se^2-.
2) HPO₄^2-.
3) ClO3^-.
4) [Co(NH₃)₅(OH)]²⁺.
5) SeO₄^-.

Answer 1

The acid-base pair which differs by a single proton is called conjugate acid-base pair.

For a given base, conjugate acid is written by the addition of a proton.

Se​​​​​2- + H+ --------> HSe​-

HSe​​​​- is the conjugate acid of Se​​​2-

HPO42- + H+ ----------> H2PO​​​4 -

H2PO​​​4 - is the conjugate acid of HPO​​​​4​​​2-

HPO​​​​4​​​2- + H+ ----------> H2PO​​​4 -

3)

ClO​​​​3​​​- + H+ --------> HClO​​​3

HClO​​​3 is the conjugate acid of ClO​​​​3​​​-

4)

SeO​​​​4 - + H+ -------> HSeO​​​4

HSeO​​​4 is the conjugate acid of SeO​​​​4​​​-

5)

[Co(NH3)5(OH)]2+ + H+ ------> [Co(NH3)5(OH​​​​​2)]+

[Co(NH3)5(OH​​​​​2)]+ is the conjugate acid of [Co(NH3)5(OH)]2+