Minerals "a" and "b" are described by this reaction: Mg(OH)₂ (solid) <=> MgO (solid) + H₂O (gas). What is the stable product when pressure equals 700 MPa and the temperature is 600 degrees celsius?

Gibbs free E at any T and p can be found with this equation: G_{T', p'} = G⁰ - ^T'_{T ref} (SdT + V_solid (P' - P_ref) + ^f_{f ref} (RT/ f)df .

The fugacity coefficient of H2O at 600 degrees celsius and 700 MPa equals 0.67. Whereas the solids in the reaction cannot be compressed.

		fH0 (kJ/ mol)	S0 (J/mol K)	fG0 (kJ/ mol)	Vol (cc/mol)
mineral a	Mg(OH)2	-972.8	77.25	-853.5	25.89
mineral b	MgO	-599.4	35.84	-695.44	09.17
Water (gas)		-277.99	165.5	-221.4	30507