The entropy change associated with the conversion of 1 kg of ice at 273 K to water vapours at 383 K is :
(Specific heat of water liquid and water vapour are `4.2kjK^(-1)kg^(-1)` and `2.0kjK^(-1)kg^(-1)` , heat of liquid fusion and vapourisation of water are `334kj kg^(-1)` and `2491kj kg^(-1)`, respectively ). (`log 273=2.436,log373=2.572, log 383=2.583`)

Options

A. `7.90 kJ kg^(-1)K^(-1)`
B. `2.64 kJ kg^(-1)K^(-1)`
C. `8.49 kJ kg^(-1)K^(-1)`
D. `9.26 kJ kg^(-1)K^(-1)`

Answer

D

Explanation

`DeltaS_(1) = (DeltaH_(fusion))/(273) = (344)/(273) = 1.22 kJ kg^(-1)K^(-1)`
`DeltaS_(2) = 4.2 In ((373)/(273)) = 1.31 kJ kg^(-1)K^(-1)`
`DeltaS_(3) = (DeltaH_(vap))/(T) = (2491)/(373) = 6.68 kJ kg^(-1)K^(-1)`
`DeltaS_(4) = 2.0((383)/(273)) = 0.05 kJ kg^(-1)K^(-1)`
`therefore DeltaS_(4) = 9.26 kJ kg^(-1)K^(-1)`.