# What is the conjugate acid for H2O (water)?

Nov 10, 2015

$h y \mathrm{dr} o n i u m$ $i o n , {H}_{3} O$

#### Explanation:

As a general rule "rough method" , add a proton (H) to make conjugate acid. Remove a proton to make a conjugate base.
In water ${H}_{2} O$ adding a proton gives you the $h y \mathrm{dr} o n i u m$ $i o n {H}_{3} O$

Nov 26, 2015

The conjugate acid is simply the original species PLUS a proton, ${H}^{+}$. The conjugate base is simply the original species LESS a proton, ${H}^{+}$.

#### Explanation:

In both instances, mass and charge are conserved. If we add a proton to water we get ${H}_{3} {O}^{+}$, the hydronium ion, which is an hypothetical species but is nevertheless useful for acid/base calculations.

Given this, you know that the conjugate base for water is $O {H}^{-}$, the hydroxide ion, and its conjugate acid is the hydronium ion, ${H}_{3} {O}^{+}$. Can you tell me the conjugate base for sulfuric acid, bisulfate ion, and hydroxide ion? Please give the answers in this thread.