6.1. A long circular cylinder 20 mm in diameter is fabricated from solid naphthalene, a common moth repellant, and is exposed to an airstream that provides for an average convection mass transfer coefficient of hm = 0.05 m/s. The molar concentration of naphthalene vapor at the cylinder surface is 5 x 106 kmol/m, and its molecular weight is 128 kg/kmol. What is the mass sublimation rate per unit length of cylinder? CA=0 h = 0.05 m/s Air D = 20 mm -CA, = 5 x 10-6 kmol/m