Project ForgeThermodynamics
First Law of Thermodynamics
GATE 2016
Hard
For water at 25°C, dps/dTs = 0.189 kPa/K and the specific volume of dry saturated vapor is 43.38 m³/kg (liquid specific volume negligible). Using the Clausius-Clapeyron equation, the enthalpy of evaporation of water at 25°C (in kJ/kg) is __________.
2450 kJ/kg(± 50 accepted)
Explanation
hfg = T·vfg·(dp/dT) = 298 K × 43.38 m³/kg × 189 Pa/K ≈ 2,443,000 J/kg ≈ 2443 kJ/kg.
Source: GATE ME 2016 Set-1 (2016)
This question is part of a 15-day revision cycle — sign in and Project Forge will bring it back the day before you'd forget it.