If water vapour is assumed to be a perfect gas, molar enthalpy change for vaporisation of 1 mol of water at 1 bar and 100°C is 41kJ mol–1. Calculate the internal energy change, when 1 mol of water is vapourised at 1 bar pressure and 100°C.
393.66 L atm
37.904 kJ mol–1
q = – w = Pex (10 – 2) = -8 litre-atm
∆H =UA– UB
Two litres of an ideal gas at a pressure of 10 atm expands isothermally at 25 °C into a vacuum until its total volume is 10 litres. How much heat is absorbed and how much work is done in the expansion ?
q = – w = Pex (10 – 2) = 0(8) = 0
q = – w = Pex (87 – 28) = 2(59) = 118
q = – w = Pex (10 – 2) = 2(8) = 16
q = – w = Pex (10 – 2) = -8
External pressure is ______ which is greater than p, piston is moved inward till the pressure inside becomes equal to Pex.
A molar property ______ is the value of an extensive property χ of the system for 1 mol of the substance.
