At what specific pressure condition does the latent heat of vaporization of water drop to zero_________________?
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Answer: E. 225.6 kg/cm2
Explanation
At the critical pressure of 225.6 kg/cm2 (approximately 22.1 MPa), the latent heat of vaporization of water drops to zero. At this unique thermodynamic endpoint, the properties of liquid water and steam merge into a single uniform phase. No phase change energy is consumed because boiling no longer occurs when transitioning into a supercritical fluid. The critical point defines the maximum temperature and pressure at which liquid and vapor can coexist in equilibrium. Latent heat of vaporization represents the energy needed to transform liquid water into steam at constant pressure. Standard thermodynamic tables verify that vaporization enthalpy decreases continuously with pressure until reaching zero at the critical point.
Operating below atmospheric pressure increases latent heat requirements rather than reducing them to zero. At 1 kg/cm2, water requires its maximum latent heat of vaporization for standard atmospheric boiling conditions. Lower pressure values like 100 or 170 kg/cm2 still require positive latent heat values for phase transformation.
- Subject
- Engineering
- Category
- Mechanical Engineering
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- —
- Difficulty
- medium
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