Question

Compute the standard free enegry of the reaction at `27^(@)C` for the combustion for methane using the give data:
`CH_(4)(g) +2O_(2)(g) rarr CO_(2)(g) +2H_(2)O(l)`
`{:(Species,CH_(4),O_(2),CO_(2),2H_(2)O(l)),(Delta_(f)H^(Theta)(kJmol^(-1)),-74.8,-,-393.5,-285.8),(S^(Theta)(JK^(-1)mol^(-1)),186,205,214,70):}`

Answer 1

`DeltaH^(@)=DeltaH_(f(CO_(2)))^(@)+2DeltaH_(f(H_(2)O))^(@)-DeltaH_(f(CH_(4)))^(@)`
`=393.5+2xx(-285.8)-(-74.8)`
`=-890kJ" "mol^(-1)`
`DeltaS^(@)=S_((CO_(2)))^(@)+2S_((H_(2)O))^(@)-S_((CH_(4)))^(@)-2S_((O_(2)))^(@)`
`=214+2xx70-186-2xx205`
`=-242JK^(-1)mol^(-1)`
`DeltaG^(@)=DeltaH^(@)-TDeltaS^(@)`
`=890-300xx(-242xx10^(-3))`
`=890+72.6=-817.4kJ" "mol^(-1)`