7 A spherical ball of solid, nonporous naphthalene, a "moth- ball," is suspended in still air. The naphthalene ball slowly sublimes, releasing the naphthalene vapor into the surrounding air by molecular diffusion-limited process. Estimate the time required to reduce the diameter from 2.0 to 0.50 cm when the surrounding air is at 347 K and 1.0 atm. Naphthalene has a molecular weight of 128 g/mol, a solid density of 1.145 g/cm³, and a diffusivity in air of 8.19 x 10-6 m²/s, and exerts a vapor pressure of 5.0 Torr (666 Pa) at 347 K.

A cylindrical tube connects two large gas tanks (Tank-1 and 2). Both tanks contain mixture of carbon dioxide (CO₂) and sulphur dioxide (SO₂). The partial pressure of carbon dioxide in Tank-1 is 80 kPa and in Tank-2 is 20kPa. Both tanks and connecting tube are at 100 kPa and 263 K. The tube is 100 mm long. The diffusion coefficient of carbon dioxide is 0.064 cm²/s at 100 kPa and 263 K, and molar mass of carbon dioxide is 44 kg/kmol. Calculate the steady-state flux of carbon dioxide through the tube, assuming ideal gas is applied. 11.755 x 10-3 mol/m².s O 7.755 x 10-3 mol/m².s 4.755 x 10-3 mol/m².s 1.755 x 10-3 mol/m².s

A cylindrical tube connects two large gas tanks (Tank-1 and 2). Both tanks contain mixture of carbon dioxide (CO₂) and sulphur dioxide (SO₂). The partial pressure of carbon dioxide in Tank-1 is 80 kPa and in Tank-2 is 20kPa. Both tanks and connecting tube are at 100 kPa and 263 K. The tube is 100 mm long. The diffusion coefficient of carbon dioxide is 0.064 cm²/s at 100 kPa and 263 K, and molar mass of carbon dioxide is 44 kg/kmol. Find the rate of flow of carbon dioxide in question 11 if the cross-sectional area of the tube is 4 mm². 47.02 x 10-⁹ mol/s 31.02 x 10-⁹ mol/s 19.02 x 10-⁹ mol/s 7.02 x 10-⁹ mol/s

A spherical mothball initially with radius, Ro, is shrinking in volume due to the sublimation of naphthalene through the air in a large room.  At room temperature (T) and pressure (PT), the naphthalene (with molecular weight as MWa) in the mothball exerts a vapor pressure (VPa).  It is of interest to investigate the rate at which the mothball is shrinking due to the diffusion of naphthalene in an air-rich environment. A. Illustrate the physical model/s that can describe the diffusion of naphthalene through the air-rich environment (room).  Indicate the control volume/s (differential volume/s) as an expression of the transfer area and distance.  Specify the components needed in establishing the shell balance.  Indicate the boundary conditions and illustrate the direction of transfer in each physical model.  Note:  Express the radial distance from the mothball surface as r, while the shrinking radius of the mothball is expressed as R.  Use and define subscripts, as necessary. B. For each…