If water vapour is assumed to be a perfect gas, molar enthalpy change for vapourisation of 1 mol of water at 1 bar and 100°C is 41kJ mol–1. The internal energy change, when 1 mol of water is vapourised at 1 bar pressure and 100°C is:
1. 35.5 kJ mol–1
2. 37.9 kJ mol–1
3. 41 kJ mol–1
4. 44.2 kJ mol–1
A swimmer coming out from a pool is covered with a film of water weighing about 18g. The internal energy of vaporization at 298K. is-
∆vap H⊖ for water at 298K= 44.01kJ mol–1
1. 38.63 kJ
2. 43.82 J
3. 41.53 kJ
4. 40.33 J
Assertion (A): | The increase in internal energy \((\Delta E ) \) for the vapourisation of one mole of water at 1 atm and 373 K is zero. |
Reason (R): | For all isothermal processes, \(\Delta E = 0 \). |
1. | Both (A) and (R) are True and (R) is the correct explanation of (A). |
2. | Both (A) and (R) are True but (R) is not the correct explanation of (A). |
3. | (A) is True and (R) is False. |
4. | (A) and (R) both are False. |
The enthalpy of fusion of water is 1.435 kcal/mol. The molar entropy change for the melting of ice at 0 °C is:
1. 10.52 cal/(mol K)
2. 21.04 cal/(mol K)
3. 5.260 cal/(mol K)
4. 0.526 cal/(mol K)