# Applying Henry's Law

Please help with the following problems:

We are asked to estimate the evaporation from a static body of water such as a lake or pond.

The dimension of the pond is 76.22m x 60.98m x 1.07m and contains ~ 4921 cubic meters of water.

The mean atmospheric air temp above the pond is 10 degrees C with a relative humidity of 68%.

The mean temperature of the water in the pond is 15 degrees C.

It is suggested that we can estimate or calculate the evaporation rate of water using Henry's Law ----- can someone show me how and please explain?

Thank you very much!

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#### Solution Preview

This question is kind of tricky, I must say! The following reference has wealth of information in it:

http://www.wpi.edu/Academics/Depts/Chemistry/Courses/General/concep10.html

I am quoting a portion from it, which is relevant for you:

"Evaporation rate is proportional to the number of molecules at the surface -- i.e., to the exposed liquid surface area. In equation form,

RE = kE(T)*A

RE = evaporation rate, with units of amount per time

A = liquid surface area

kE(T) = rate constant for evaporation, with units of amount per unit area per unit time.

(The constant, kE, is called a rate constant. It is a proportionality constant relating the evaporation rate to macroscopic variables on which rate depends. In this case, surface area is the only variable of importance, as long as temperature is constant. The size of the ...

#### Solution Summary

This solution helps with problems involving the application of Henry's law.