MathBench > Cellular Processes

Diffusion through a Membrane

And what you've all been waiting for

Using the equation governing the flow of sugar across a membrane:

and given that

The area of the membrane between the two solutions is 2 cm2

The concentration of the solution on the left side of the membrane = 0.4 M

The concentration of the solution on the right side of the membrane = 0.1 M

P= 0.02 cm/sec

What is the rate of diffusion (flow rate) across the membrane for the following concentrations? This kind of problem requires straightforward substitution...

0.02cm/sec x 2 cm2 x (0.4 M sugar - 0.1 M sugar)

= 0.012 moles/second

The flux (flow rate divided by the area) would therefore be 0.012 / 2 = 0.006 mol cm -2 s -1

What would happen if we doubled the permeability constant?

What if we doubled the area of the membrane?

What if we doubled the concentration on the left?