One kilogram of a substance is contained in a piston cylinder device as a saturated liquid.
Heat is added at constant pressure until all the liquid in the device has turned into a saturated
vapour.
a) Demonstrate that the heat added to the substance in the piston cylinder device (on a
per kilogram basis) during this process is equal to $h_{fg}$ (specific enthalpy difference
between the saturated vapour and saturated liquid states). Ignore all changes in
potential and kinetic energy of the substance.
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b) During the above process, 2382 kJ of heat is added at a constant temperature of 50 °C
and a constant pressure of 12.352 kPa to the substance. The volume of the substance
increases by 12.025 m³/kg. Use the Clapeyron equation to estimate the saturated
pressure of the substance at a temperature of 60 °C.
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