Change in internal energy during vapourization of water

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SUMMARY

The change in internal energy during the vaporization of water at 100 degrees Celsius is not constant, despite the temperature remaining the same. The enthalpy of vaporization, quantified as x joules per mole, indicates that energy is required for the phase change from liquid to vapor. This energy, known as latent heat, is essential for understanding the thermodynamic processes involved in vaporization. The misconception that internal energy remains constant during this phase change has been clarified through the discussion.

PREREQUISITES
  • Understanding of thermodynamics and phase changes
  • Familiarity with the concept of latent heat
  • Knowledge of enthalpy and internal energy
  • Basic principles of ideal gas behavior
NEXT STEPS
  • Study the concept of latent heat in detail, focusing on latent heat of vaporization and fusion
  • Explore the thermodynamic equations related to phase changes, including the Clausius-Clapeyron equation
  • Investigate the properties of water as an ideal gas and its deviations from ideal behavior
  • Learn about the relationship between enthalpy, internal energy, and heat transfer in thermodynamic processes
USEFUL FOR

Students studying thermodynamics, physicists, chemists, and anyone interested in the principles of phase changes and energy transfer in water.

shivambehl
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Homework Statement


Assuming water to be an ideal gas, enthalpy of vaporization is x joules per mole. I have to find change in internal energy an 100 degree Celsius for one mole of water. also find heat absorbed.

Homework Equations

The Attempt at a Solution


I initially thought that during vaporization of water, temperature does not change and hence internal energy should remain constant (assuming ideal gas behaviour by water ).
but my assumption was found to be wrong.

I am totally confused...
 
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shivambehl said:

Homework Statement


Assuming water to be an ideal gas, enthalpy of vaporization is x joules per mole. I have to find change in internal energy an 100 degree Celsius for one mole of water. also find heat absorbed.

Homework Equations

The Attempt at a Solution


I initially thought that during vaporization of water, temperature does not change and hence internal energy should remain constant (assuming ideal gas behaviour by water ).
but my assumption was found to be wrong.

I am totally confused...
It takes energy to accomplish the phase change from liquid to vapor. The fact that this phase change occurs at constant temperature does not necessarily mean that the energy in the water is constant. Same deal when water changes phase from liquid to solid. Energy must be removed from the liquid water to turn it into ice. The energy which must be added/removed is known as latent heat. For freezing water, this is the latent heat of fusion. For making steam, this is the latent heat of vaporization.

https://en.wikipedia.org/wiki/Latent_heat
 

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