Question

1. A spherical ball of naphthalene (mothball) is suspended in still air at 347 K. Its vapor pressure at this temperature is 666 Pa. Determine the concetration of naphthalene in the air that is in contact with the mothball. Assuming that the mass transfer coefficient for still air is given by D/a Where D is the diffusion coefficient and a is the radius of the sphere, determine the rate mass loss from the mothball of radius 2 cm. Take . The molecular weight of naphthalene is 128 g/mol. How long will it take for the ball radius to decrease to 0.5 cm. The density of the mothball is 1.15 g/cm3.

Answer 1