Temperature affects the dissociation of water into hydronium and hydroxide ions. At 5 °C, [H₃O⁺] = 4.32×10⁻⁸ mol/kg of water, at 25 °C, [H₃O⁺] = 1.00×10⁻⁷ mol/kg of water, and at 45 °C, [H₃O⁺] = 1.97×10⁻⁷ mol/kg of water. Determine if the dissociation of water into hydronium and hydroxide ions is endothermic or exothermic.

• A. Endothermic
• B. Exothermic

Answer: (A)