Why we use enthelpy when we calculate latent heat?

Thread starter seungwoo Park
Start date May 11, 2017
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Heat Latent heat

In summary, entropy is used when calculating latent heat because it accounts for the disorder or randomness in a system during a phase change. Entropy and latent heat are closely related as both involve energy and changes in state. However, there are other factors such as specific heat and temperature that also play a role in calculating latent heat. Entropy is not directly measurable, but can be calculated using thermodynamic principles and is determined by measuring the change in temperature and heat in a system. Entropy can be negative in a system, typically when energy is removed and disorder decreases, such as during a phase change from gas to liquid.

May 11, 2017

seungwoo Park

Why we use enthalpy(h) instead of internal energy(u) when we consider latent heat?

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May 11, 2017

BvU

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Because a phase change is generally accompanied by a volume change and therefore involves pV work as well.

[edit] I notive you haven't had the customary

Hello seungwoo, :welcome:

So here it is, albeit belated !

Last edited: May 11, 2017

Related to Why we use enthelpy when we calculate latent heat?

1. Why do we use entropy when calculating latent heat?

Entropy is a measure of the disorder or randomness in a system. When calculating latent heat, we are dealing with a phase change from solid to liquid or liquid to gas. This change in state involves a significant change in the arrangement of molecules, leading to an increase in disorder. Entropy helps us account for this change and better understand the energy required for the phase transition.

2. How is entropy related to latent heat?

Entropy and latent heat are closely related because both concepts involve energy and changes in the state of a substance. Entropy is a factor in determining the amount of latent heat required for a phase change, as it represents the amount of energy that is dispersed or "lost" during the transition.

3. Is entropy the only factor in calculating latent heat?

No, entropy is not the only factor in calculating latent heat. Other factors such as specific heat and temperature also play a role. However, entropy is an important factor to consider as it helps us understand the energy required for a phase change and how it relates to the disorder of the system.

4. How do we measure entropy in a system?

Entropy is not directly measurable, but it can be calculated using thermodynamic principles. There are various equations and methods for calculating entropy, depending on the specific system and conditions. In general, the change in entropy can be determined by measuring the change in temperature and heat in a system.

5. Can entropy be negative in a system?

Yes, entropy can be negative in a system. This typically occurs when energy is being removed from a system, leading to a decrease in disorder and therefore a decrease in entropy. An example of this is when a substance goes through a phase change from gas to liquid, where the molecules become more organized and the entropy decreases.