The intrinsic auto-ionization of water is fundamentally represented by , with the equilibrium consta — Ionic Equilibrium Chemistry Question

💡 Solution & Explanation

The ionic product $K_w$ applies universally to any aqueous solution at a given temperature. Because the cleavage of the covalent O-H bond is endothermic, Le Chatelier's principle strongly dictates that heating shifts the equilibrium forward, substantially increasing $K_w$. Since $pK_w = -\log K_w$, an increase in $K_w$ mathematically leads to a decrease in $pK_w$. Therefore, at $90^\circ C$, $K_w > 10^{-14}$ (making statement C entirely incorrect). At standard $25^\circ C$, $K_w = 10^{-14}$, meaning $[H^+] = 10^{-7} \text{ M}$.