InterviewSolution
Saved Bookmarks
InterviewSolution
| 1. |
Calculate the standard free energy change for the formation of methane at `300K`: `C("graphite") +2H_(2) (g) rarr CH_(4)(g)` The following data are given: `Delta_(f)H^(Theta) (kJ mol^(-1)): CH_(4)(g) =- 74.81` `Delta_(f)S^(Theta)(kJ mol^(-1)): C("graphite") = 5.70, H_(2)(g) = 130.7 CH_(4)(g) = 186.3` |
|
Answer» `Delta_(r)G^(Theta)` can be calculated form the relation: `Delta_(r)G^(Theta) = Delta_(r)H^(Theta) - TDelta_(r)S^(Theta)` `C("graphite") +2H_(2)(g) rarr CH_(4)(g)` `Delta_(f)H^(Theta) = Delta_(f)H^(Theta) (CH_(4)) -[Delta_(f)H^(Theta)(C ) +2Delta_(f)H^(Theta)(H_(2))]` `=- 74.81 -0 -0 =- 74.81 kJ mol^(-1)` `Delta_(r)S^(Theta) S_(m)^(Theta) (CH_(4)) -[S_(m)^(Theta) (C )+2S_(m)^(Theta)(H_(2))]` `= 186.3 -[5.70 +2 xx 130.7]` `= 180.3 - 267.1` `=- 80.8 J K^(-1) mol^(-1)` `:. Delta_(r)G^(Theta) = Delta_(r)H^(Theta) -TDelta_(r)S^(Theta)` `=- 74.81 -300 xx (-80.0 xx 10^(-3))` `=- 74.81 +24.4 =- 50.57 kJ mol^(-1)` |
|