Calculate the diffusion coefficient for the diffusion of a haemoglobin molecule through water at a temperature of 25°C. The effective cross sectional area of a haemoglobin macromolecule is 3.6 *10^-9 m² and the viscosity of water is 8.90 *10^-4 kg m^-1 s^-1 at this temperature.

Question

Quizplus · Accepted Answer

The diffusion coefficient (D) can be calculated using the Stokes-Einstein equation: D = kT / (6πηr), where k is the Boltzmann constant (1.38×10^-23 J/K), T is the temperature in Kelvin (298K for 25°C), η is the viscosity of the solvent (8.90×10^-4 kg/m·s for water at 25°C), and r is the effective radius of the particle. Given the effective cross-sectional area (A = πr^2), we can solve for r and then for D. The correct calculation leads to a diffusion coefficient in the order of magnitude of 10^-10 m^2/s, which matches choice C.

Calculate the Diffusion Coefficient for the Diffusion of a Haemoglobin