Hydrides are rare earth metals, M, that have the ability to react with hydrogen to form a different substance MH x with a release of energy. The hydrogen can then be released, the reaction reversed, by heat addition to the MH x. In this reaction only the hydrogen is a gas so the formula developed for the chemical equilibrium is inappropriate. Show that the proper expression to be used instead of Eq. 15.34 is in (PH2/Po) = G0/RT when the reaction is scaled to 1 kmol of H2.