Question

How does $K_w$ vary with temperature and why ?

Answer 1

Ionic products are temperature dependent because the ionic product is directly proportional to the temperature.

By Le-chatelier's principle as the temperature increases, the position of equilibrium shifts to the right of the equation to minimize the effect of increased temperature.

This means with the increase in temperative the concentration $\left[H^{+}\right]$ and $\left[O{H}^{-}\right]$ ions will increase which will result in increased value af Kw as formed reaction is favoured. This means that the ionic product is only dependent on temperature and is unaffected by any other changes.