# How would you identify the acid, base, conjugate acid and conjugate base in the following reaction: HCN + SO4^(2-) --> HSO4^(-) + CN^(-)?

Nov 22, 2015

Acid, hydrogen cyanide, "Prussic" acid; base, sulfate ion. The conjugate species is idenitified by proton addition OR removal.

#### Explanation:

Acid, $H - C \equiv N$; conjugate base, $N \equiv {C}^{-}$, cyanide anion.

Base, $S {O}_{4}^{2 -}$, sulfate ion; conjugate acid. $H S {O}_{4}^{-}$.

The conjugate acid is simply the starting material PLUS a proton; the conjugate base is simply the starting material MINUS a proton. Both mass and charge are conserved. SO the conjugate base of sulfuric acid, ${H}_{2} S {O}_{4}$, is $H S {O}_{4}^{-}$, and the conjugate base of this anion is $S {O}_{4}^{2 -}$.

What is the conjugate acid of sulfuric acid, ${H}_{2} S {O}_{4}$? I assure you that it exists.