The water reaction is even more extreme. The reaction is
(g) + (g)
= -109.3 kcal per 2 moles of
and the equilibrium-constant expression is
Even without putting pencil to paper we can see that there should
be infinitesimal amounts of hydrogen and oxygen gases at equilibrium.
The equilibrium mixture should be nearly pure water. As the large
indicates, the forward reaction will be very spontaneous.
This equilibrium-constant expression, unlike that for HCl, has different
powers of concentration in the numerator and denominator. If concentrations
are specified as partial pressures in atmospheres, then
will have units of atm