Topic: Thermodynamics
What is the change in entropy when water is vaporized at 100 °C. Latent heat of vaporization of water may be taken as 2238 kJ/kg.
- A. 22.38 kJ/kg K
- B. 2.238 kJ/kg K
- C. 6 kJ/kg K
- D. 100 kJ/kg K
Answer: C. 6 kJ/kg K
Explanation: The change in entropy dS during phase change at constant temperature is dQ / T. Temperature T = 100 + 273 = 373 K. Latent heat dQ = 2238 kJ/kg. Therefore, dS = 2238 / 373 = 6 kJ/kg K.