Delta _(C) U^( Theta ) of formation of CH_(4(g)) at certain temperature is -393 "kJ mol"^(-1). The value of Delta_(f) H^( Theta ) is

Delta _(C) U^( Theta ) of formation of CH_(4(g)) at certain temperatur

1.	Delta _(C) U^( Theta ) of formation of CH_(4(g)) at certain temperature is -393 "kJ mol"^(-1). The value of Delta_(f) H^( Theta ) is
Answer» <P>zero `LT Delta_(f) U^( Theta )` `gt Delta_(f) U^( Theta )` equal to `Delta_(f) U^( Theta )` Solution :For the reaction, `CH_(4(g)) + 2O_(2(g)) to CO_(2(g)) + 2H_(2) O_((l))` `Deltan_(g) = (n_(p) - n_(r) )_(g) = 1-3 = -2` `Delta_(f) H^( - Theta )= Delta_(r) U^( Theta ) + Deltan_(g) "RT"` As `Deltan_(g) = -2` `therefore Delta_(f) H^( Theta ) lt Delta_(f) U^( Theta )`