# In Ka (acid equilibrium constant) what do the concentrations on the other side represent?

## In Ksp solubility, they represent how many ions can be in a litre before a solution is saturated, but what about Ka?

Feb 10, 2017

We refer to the acid base equilibrium:

$H A \left(a q\right) + {H}_{2} O \left(l\right) r i g h t \le f t h a r p \infty n s {H}_{3} {O}^{+} + H {O}^{-}$

#### Explanation:

And ${K}_{a}$ is just your garden variety equilibrium expression:

${K}_{a} = \frac{\left[{H}_{3} {O}^{+}\right] \left[H {O}^{-}\right]}{\left[H A\right]}$

And thus ${K}_{a}$ is the ion product multiplied by the original concentration of the acid.