Which expression represents the concentration of OH– in solution? a. 10–14 / [H3O+]
b. [OH–] / 10–14
c. 10–14 – [H3O+]
d. 10–14 x [H3O+]

10^-14 / [H3O+]
Explanation:
Hydronium (H3O+) and hydroxide ions (OH-) are both present in pure water and in all aqueous solutions.
Their respective concentrations in water are 10^-7 M each and are inversely proportional to each other as given by the ion product of water, Kw.
Kw = [H3O+][OH−]
Where Kw = 1.0 * 10^-14,
[H3O+] = concentration of hydronium ions
[OH-] = concentration of hydroxide ions
Therefore, [OH-] = Kw / [H3O+]
[OH-] = 10^-14/[H3O+]

Spontaneity tell us the direction of the reaction, but not how fast it goes. gibbs free energy brings together enthalpy, entropy and temperature in one easy formula. g = h - ts. and, finally the sign of delta g is always negative for a spontaneous reaction.

1. o2(g)as a product