What is the ion-product constant, K_w?

Jun 11, 2017

For water, this is the measure of the $\text{autoprotolysis reaction}$....

Explanation:

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

And ${K}_{w} = \left[H {O}^{-}\right] \left[{H}_{3} {O}^{+}\right] = {10}^{-} 14$ at $298 \cdot K$.

And when we take $- {\log}_{10}$ of both sides we get the useful expression...........

$p H + p O H = 14$, where $p H = - {\log}_{10} \left[{H}_{3} {O}^{+}\right]$ etc.

How do you think ${K}_{w}$ would develop if non-standard conditions pertained; e.g. if temperature was say $373 \cdot K$. Would ${K}_{w}$ remain constant, decrease, increase? Remember that the autoprotolysis reaction as shown is a $\text{bond-breaking reaction}$.