A pistion exerting a pressure of `1.0atm` rests on the surface of water at `100^(@)C`. The pressure is reduced to smaller extent and as a result `10g` of `H_(2)O` eveportes and abosrb `20 kJ` fo heat. Determine

Options

A. a) `DeltaH`
B. b) `Latent` `heat` `of` `vapourisation`
C. c) `W`
D. d) `DeltaU`

Explanation

i. `DeltaH =+20 kJ`
ii. Moles `= (10)/(18) = 0.56`
`rArr` Latent heat of vapourisation
`= (DeltaH)/(n) = (20)/(0.56) = 35.71 kJ mol^(-1)`
iii. `w =- nRT =- 0.56 xx 8.31 xx 10^(-3) xx 373 =- 1.735 kJ`
iv. `DeltaU = DeltaH +w = 20 - 1.735 = 18.265 kJ`