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**1. Homework Statement**

Assuming:

Organism weight = 25 g

Organism lenght = 30 cm

[Na+ (ECF)] = 200 mM

[Na+ (water)] = 500 mM

ΔX(gill) = 6 μm

ΔX(skin) = 25 μm

A(gill) = 5.0 cm^2/gm

A(skin) = 10 cm^2/gm

Dk(gill) = 2 X 10^4 cm^2/s

Dk(skin) = 1 X 10^4 cm^2/s

Calculate the Na+ rate of diffusion through the skin using Fick's equation: (Dk)(A)((C1-C2)/dX)

**2. Homework Equations**

Fick's equation: (Dk)(A)((C1-C2)/dX)

**3. The Attempt at a Solution**

I'm not sure too sure if the answer that I'm getting is right. It seems to be too high and the units seem confusing.

Rate = (1 X 10^4)(10)((500-200)/25*10000) = 120 cm^3*mM/s*gm.

I am not sure if I should also use the weight and the length of the organism.

Thanks