T H E M E T H A N E EQUILIBRIUM IV BY R. C . CANTELO
The data given in the third paper' of this series permits the calculation of the free energy decrease attending the synthesis of methane from arnorphou. carbon and hydrogen. The free energy expression for the Second Law of Thermodynamics i. given by (1
(T)$.
(IT and A H ,
=
the increase in heat content may be expressed in terms of the heat capacities of the substances involved. If A C represents the difference in the heat capacities of the products antl the reactant,s, the equation becomes - -A_ F - J J A C . ~ T + A H , , ~ ~ + ~ T T2 where AHc and I are constants of integration. AH, may he calculated from the fact that for the reaction 2H? ;--t C H I ; - AH?,, = 2 1 , 7 3 0 calories C (aniorph) If AC be expressed in series form, AC' = AC, cuT + PT' --and the free energj- expression simplifies to -.IF - -AH" __ A C in ~ T + E T +;TZ I T T
+ +
+
+
or
- AF
=
-AHo
+-
+ .I(:,T In T + E T2 + P6 T3 + I T -
Dixon,
