CHE 31301 MASS TRANSFER ________________________ LAST NAME, FIRST QUIZ #1I. A coal particle burns in air at 1145oK, 1 atm. The process is limited by diffusion of the oxygencounterflow to the CO2 and CO that are formed at the particle surface where 3C + 2.5O2 --> CO + 2CO2Assume that the coal is pure carbon with a density of 1280 kg/m3 and that the particle is sphericalwith an initial diameter of 0.015 cm. Air (21 mol% oxygen, 79 mol% nitrogen) exists severaldiameters away from the sphere.1. NCO = ___NOxyen 2. The mole fraction of oxygen at the particle surface in the gas phase is ___3. The mole fraction of carbon at the particle surface in the solid phase is ___II.1 ftz3 ft2 ft1. The molar concentration of H2O at the top of the tank(z = 0) is ____________2. The molar concentration of H2O at the air-water interfacein the gas phase is ___________A tank containing water has its top open to air. The tank is cylindricalwith a diamter of 2 ft. The liquid level is maintained at a level of 3 ftbelow the top of the tank as shown in sketch. The surrounding air is at310oK, 1 bar, and 40 percent relative humidity.Note: Gas constant = 8314 Pa.m3/kmol.K, at 40 % relative humidity, partial pressure of water = 0.4*watervapor pressureMolecular weight of air = 28.9Molecular weight of water = 18.0 , density of water at 310oK = 997 kg/m3Vapor pressure of water at 310oK = 0.06221 bar, 1 bar = 105 Pa.III. (10 pts) In a hot combustion chamber, oxygen diffuses through air to the carbon surface where it reacts to make CO and CO2. The mole fraction of oxygen at z = L is 0.21. The reaction may be assumed to be instantaneous. No reaction occurs in the gas film. The chamber is at 1 atm, 1000oK, and L = 0.1 m. The diffusivity of oxygen at these conditions is 0.35 cm2/sec. Determine the molar flux of oxygen if the following reaction occurs at the carbon surface:4C + 3O2 --> 2CO + 2CO2Data: Gas constant = 0.08205 atm.m3/kmol.KCHE31301 MASS TRANSFER QUIZ #21 ftz3 ft2 ftA tank containing water has its top open to air. Thetank is cylindrical with a diameter of 2 ft. The liquidsurface is maintained at a level 3 ft below the top ofthe tank as shown in the sketch. The surrounding air isat 310oK, 1bar, and 40 percent relative humidity. 1. If R is the radius of the tank in the range 0  z  3 ft, then an expression for R as a function of z is ___________2. A. The molar flux of water vapor is independent of z.B. If air is insoluble in water the molar flux of air is independent of z.I. A and B are true II. Only A is true III. Only B is true IV. A and B are false3. A. The molar concentration of water vapor is independent of z.B. The total molar concentration is independent of z.I. A and B are true II. Only A is true III. Only B is true IV. A and B are false4. A. If the surrounding air is saturated with water vapor then the molar flux of H2O is zero.B. If air is insoluble in water then the molar flux of air is zero.I. A and B are true II. Only A is true III. Only B is true IV. A and B are false5. If the mole fraction of H2O is 0.1 then the mass fraction of H2O is ____________Data: Gas constant = 8314 Pa.m3/kmol.KMolecular weight of air = 28.9Molecular weight of water = 18.0 , density of water at 310oK = 997 kg/m3Vapor pressure of water at 310oK = 0.06221 bar, 1 bar = 105 Pa.2. (10 pts) In the high-temperature combustion of coal in a power plant (1145oK), the average size(diameter) of the coal particle is 0.02 cm. For complete combustion, the reaction at the surface ofthe coal particle is 3C + 2O2 --> 2CO + CO2. Assuming that the combustion reaction is controlledby the diffusion of oxygen to the coal particle surface, estimate the instantaneous consumption rateof oxygen (mol/s) by the average size coal particle. Do not neglect the convection term. Assume thediffusion coefficient of O2 at this temperature is 1.4 cm2/s and that far away from the particle thepartial pressure of O2 is 0.21 atm. Gas constant R = 82.06 atm.cm3/mol.oK.CHE31301 MASS TRANSFER QUIZ #3 I. Consider a spherical porous catalyst in which species A diffuses into the catalyst and undergoesan irreversible reaction A --> B. The reaction is distributed homogeneously throughout the particleand the conversion of A to B can be expressed by first-order kinetics. The system is steady atconstant T and P.1. A. The rate of A diffuses into the catalyst will be the rate of A reacted within the catalyst only if the reaction is very fast compared to the rate of diffusion.B. The concentration of B is highest at the surface of the spherical catalyst. a. A and B are true b. Only A is true c. Only B is true d. A and B are false2. A. The concentration of A is a constant at r = 0.5R where R is the radius of the catalyst.B. The concentration of B is a minimum at the center.a. A and B are true b. Only A is true c. Only B is true d. A and B are false 3. A. Concentration of species A must be known at time t = 0 to solve for the amount of A reacted within the catalyst.B. The concentration profile can not be solved if the concentration of A is given at some other positon and not at the surface.a. A and B are true b. Only A is true c. Only B is true d. A and B are false4. A. NA = NBB. The total concentration within the catalyst is a constant.a. A and B are true b. Only A is true c. Only B is true d. A and B are false5. The catalyst is 8.010-3 m in diameter and the first order reaction rate constant is 1.510-7m/s. Concentration of A at the catalyst surface (r = R) is 18 kgmol/m3. If the diffusion rate is muchfaster than the reaction rate, determine the consumption rate of species A within the catalystparticle.II. (10 pts) Species A diffuses into a spherical particle where it is consumed by zero order reactionrA = - ko where ko = 1.5x10-5 mol/cm3.s. The particle diameter is 0.1 cm and the diffusivity of A inthe particle is 1.26x10-5 cm2/s. Determine the concentration of A at the center of the particle if theconcentration of A at the particle surface is 0.025 mol/cm3.CHE31301 MASS TRANSFER