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# What is the value of latent heat of condensation of water?

Jul 22, 2017

The latent heat of condensation of a substance is the heat liberated by a unit mass of the substance's vapor at its boiling point as it condenses into liquid phase.

(It is essentially the "opposite" of the latent heat of vaporization).

This value depends on the temperature, and according to this Wikipedia page, if the temperature range is from $- 25$ $\text{^"o""C}$ to $40$ $\text{^"o""C}$, the value (for water) can be approximated by the cubic function

• ${L}_{\text{water}} \left(T\right) = 2500.8 - 2.36 T + 0.0016 {T}^{2} - 0.00006 {T}^{3}$ $\text{J/g}$

where $T$ is the temperature in degrees Celsius.

As an example, we can use this equation to find the latent heat of condensation at $25$ $\text{^"o""C}$:

${L}_{\text{water}} \left(T\right) = 2500.8 - 2.36 \left(25\right) + 0.0016 {\left(25\right)}^{2} - 0.00006 {\left(25\right)}^{3}$ $\text{J/g}$

= color(red)(2442 color(red)("J/g"