3. Air at 10C is flowing through a circular pipe ( coating naphthalene with inner diameter 0.02664 m, length 2 m ), and the bulk velocity of water is 15 m/sec. The diffusivity of benzoic acid in water is 5.1613*10-6 m/sec. Calculate the average naphthalene concentration at the outlet and the total mole of naphthalene dissolved per second, (the vapor pressure and molecular weight of solid benzoic acid being 0.0209 mmHg, 128.2. density and viscosity of air being 1.249 kg/m, 0.000017858kg/m/sec)