For a sample of pure water, — Ionic Equilibrium Chemistry Question

💡 Solution & Explanation

The dissociation of water ($H_2O \rightleftharpoons H^+ + OH^-$) is an endothermic process. As temperature increases, the equilibrium shifts forward, increasing both $[H^+]$ and $[OH^-]$. Since $pH = -\log[H^+]$ and $pOH = -\log[OH^-]$, an increase in ion concentrations leads to a decrease in both pH and pOH. Therefore, correct answer is D.