EK1001 Q718: The autoionization of water (shown below) is an endothermic reaction. 2H2O --> H3O+ + OH- as the temperature of pure water increases the pH: A. decreases because [H+] increases B. increases because [OH-] increases C. increases because [H+] increases D. remains at 7 because [H+] equals [OH-] even after an equilibrium shift. I thought it would be D, but the answer is A. Why? It's endothermic, so adding heat should drive the equilibrium towards the products... but I don't see why pH would change with heat.