# Diffusion Practice Problems with Answers

1. The volume of compartment A = volume of B = 1 liter. The membrane between A and B allows the diffusion of drug Z. At the start of the experiment, the concentration of drug Z in compartment A is 500 nM (500 x 10-9 M) and is 100 nM (100 x 10-9 M) in compartment B.

a. At equilibrium, what will be the concentration of drug Z in A? in B?

b. Why?

2. The volume of compartment A = 4 liters; the volume of compartment B = 1 liter. At the start of the experiment, there are 240 nmoles (240 x 10-9 moles) of drug Z in A and 60 nmoles (60 x 10-9 moles) in compartment B.

a. At equilibrium, how many moles of drug Z will be in compartment A? in compartment B?

b. Why?

3. The volume of compartment A = 1 liter. In compartment B, fluid flows through at the rate of 10 liters per minute; this fluid flows through the compartment only once and is not re-circulated. At the start of the experiment, the concentration of drug Z in A is 100 x 10-9 M, and 0 in B. Under these conditions, 10% of the drug Z in A crosses to B each minute.

a. What is the concentration of drug Z in A after 5 minutes?

b. What is the concentration of drug Z in A at equilibrium?