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

💡 Solution & Explanation

The self-ionization of water ($H_2O$ ⇌ H+ + OH-) is an endothermic process (ΔH > 0). According to Le Chatelier's principle, an increase in temperature shifts the equilibrium to the right, increasing both [H+] and [OH-] simultaneously. Since pH = -log[H+] and pOH = -log[OH-], an increase in both concentrations results in a decrease in both pH and pOH values.