A Lower Tank Contains Water While an Upper Tank Contains

Multiple Choice

A lower tank contains water while an upper tank contains air with a negligible concentration of water vapor. A tube with a circular cross section and radius 0.050 m is inserted between the two tanks. The length of the tube is 0.25 m. The diffusion coefficient of water vapor through air is 2.4 × 10^-5 m²/s. The concentration of water vapor just above the surface of the water is 1.7 × 10^-2 kg/m³. If the water vapor is removed from the upper tank so that the concentration there remains nearly zero, what mass of water vapor diffuses through the tube each hour?

A) 4.6 × 10^-5 kg
B) 2.0 × 10^-6 kg
C) 7.1 × 10^-7 kg
D) 1.3 × 10^-8 kg
E) 8.2 × 10^-8 kg