Phase transitions are ubiquitous in nature. We are all familiar with the different phase of water (vapour, liquid and ice) and with the change from one to another, the change of phase are called phase transitions. There are six ways a substance can change between these three phase, melting, freezing, evaporating, condensing sublimation and decomposition.
At `1 atm` pressure vaporisation of `1` mole of water from liquid `(75^(@)C)` to vapour `(120^(@)C)`.
`C_(v)(H_(2)O,l)=75 J "mole"^(-1)K^(-1), C_(p)(H_(2)O,g)=33.3J"mole"^(-1)K^(_1)`
`Delta H_(vap)` at `100^(@)C=40.7KJ//"mole"`
Calculate change in internal energy when
Water liquid at `75^(@)C` to `100^(@)C` ?

Options

A. `1875 J`
B. `13125 J`
C. `-1875 J`
D. `-13125 J`

Answer

A