At what critical pressure value does the latent heat of vaporization drop to zero________________?
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Answer: A. 225.65 kgf/cm2
Explanation
At the critical point of water, corresponding to a pressure of 225.65 kgf/cm2, the latent heat of vaporization drops entirely to zero. At this specific pressure and temperature threshold, saturated liquid and saturated vapor states become completely indistinguishable. No phase change energy is required because boiling ceases and water transitions directly into a supercritical fluid. Latent heat of vaporization is the thermal energy required to convert a liquid into gas without changing its temperature. The critical pressure of water equals approximately 22.1 megapascals, which converts to 225.65 kgf/cm2. Beyond the critical point, distinct liquid and vapor phases no longer exist within the thermodynamic property tables.
A pressure of 273 kgf/cm2 exceeds the critical point, meaning vaporization enthalpy has already reached zero at lower pressures. At 100 kgf/cm2, water still requires a substantial positive latent heat of vaporization to undergo phase change. Standard atmospheric pressure of 1 kgf/cm2 features the maximum latent heat of vaporization for water during boiling.
- Subject
- Engineering
- Category
- Mechanical Engineering
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- —
- Difficulty
- medium
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