If `Delta _(f) G ^(@) (H_(2)O, l) = - 237 . 19 kJ mol ^(-1)` and `Delta _(f) G ^(@) (H _(2)O. g) =- 228.59 kJ mol ^(-1),` the vapour pressure of water at 298 K would be about

Options

A. `0.01 atm`
B. `0.02 atm `
C. `0.03 atm`
D. `0.05 atm `

Answer

C

Explanation

`Delta _(f) G ^(@) (H _(2) O , g ) - Delta _(f) G ^(@) ( H _(2) O, l ) =(- 228 . 59 + 237. 19) kJ mol ^(-1) = 8.6 kJ mol ^(-1)`
`P _(H_(2)O (g))//atm = K ^(@)=` antilog `( - Delta G ^(@) // 2. 30 RT)`
= antilog `{ 8. 6 xx 10 ^(3) // ( 2. 303 xx 8. 314 xx 298) }=` antilog `( - 1. 507) = 0.03`