What kind of equilibrium constant can be calculated from ∆ G ∘ value for a reaction involving only gases?

For reaction involving gases only. ∆ G ∘ = - 2 . 303 RT log K p ∴ K p can be calculated if ∆ G ∘ is known. Where, ∆ G ∘ = Change in standard Gibbs free energy. R = 0 . 0820575 atm mol - 1 K - 1 or 8 . 31447 J mol - 1 K - 1 T = Temperature in kelvin K p = Equilibrium constant with respect to pressure

H 2 O + H 2 O ⇌ H 3 O + + OH - .The ionic product of water is 1 × 10 - 14 at 25 ∘ C and 3 . 0 × 10 - 14 at 40 ∘ C . Is the above process endothermic or exothermic?

The ionic product of water increases with increase in the temperature.The formation of hydrogen ions (hydroxonium ions) and hydroxide ions from water is an endothermic process. According to Le Chatelier principle, the increase in temperature of the water will move the equilibrium to lower the temperature again. It will do that by absorbing the extra heat(endothermic). That means that the forward reaction will be favoured, and more hydrogen ions and hydroxide ions will be formed.