Temperature concerning pH, endothermic or exothermic?

Question

At 298 K, the K2 is 1 x 10^-14 M, while at 373 K, the Kw is 51 x 10^-14, Is the reaction exothermic or endothermic? Explain your answer.


I want to say endothermic because the concentration is higher, but I'm not sure.

Am I right or wrong?

Answer 1

The fact that K has got larger on heating, and the knowledge that equilibria go in the endothermic direction on heating, confirm that you're right.

Answer 2

Pure water is always neutral. Temperature increases the activity of H+ which gives an apparent rise in concentration and so the value of pH is less. It should be endothermic since heat has been added to the system