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Help calculating a diffusion rate using Fick's equation. 
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#1
Feb1912, 09:25 PM

P: 18

1. The problem statement, all variables and given/known data
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)((C1C2)/dX) 2. Relevant equations Fick's equation: (Dk)(A)((C1C2)/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)((500200)/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 


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