The diffusion coefficient for calcium ions crossing a biological membrane 10nm thick is 300 micrometers squared/second and the concentration difference of calcium ions across the membrane is 400 mol/m^2 (Molar mass of calcium is 40 kg/mol)

Question

Determine the number of moles of calcium ions that move through a 1 micrometer*1 micrometer cross sectional area of the membrane in 1 second

Answer 1

Diffusion rate (moles/area*sec) =
(Concentration gradient)*(Diff. coefficient)

Shouldn't the concentration difference have units of mole/m^3 ? Or are you providing the value of
(Diff. coefficient)/(thickness) ?