30.2 A 1.75-cm diameter naphthalene mothball is suspended in an air stream at 280 K, 1.0 atm, and constant velocity of 1

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30.2 A 1.75-cm diameter naphthalene mothball is suspended in anair stream at 280 K, 1.0 atm, and constant velocity of 1.4 m/s.Solid naphthalene exerts a vapor pressure of 2.8 Pa at 280 K.Consequently, the naphthalene very slowly sublimes into the passingair stream, with the rate limited by convective mass transfer. Thedensity of solid naphthalene is 1.14 g/cm3 , and the molecularweight is 128 g/mole. a. What is the initial evaporation rate ofnaphthalene mothball? NA = 1.32 x 10-8 kgmol/(m2 ∙ s) b. How longwill it take for the mothball to shrink to half of its originaldiameter? Remember: As the mothball shrinks, its diameter isdecreasing, which in turn affects the Reynolds and Sherwoodnumbers. t = 720 hr