Q. What is the unit of diffusion coefficient?

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Q. What is the molecular weight of ammonia?

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Q. What is the molecular volume of air at normal boiling point?

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Q. What is the value of Schmidt number for hydrogen?

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Q. Estimate the diffusion coefficient for ammonia in air t 25 degree Celsius temperature and one atmospheric pressure.

For ammonia,

Molecular weight = 17
Molecular volume = 25.81 cm³/gm mole

For air,
Molecular weight = 29

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Q. Estimate the diffusion coefficient of carbon monoxide through air in which the mole fractions of each constituents are
O₂ = 0.18

N₂ = 0.72

CO = 0.10

The gas mixture is at 300 K and 2 atmosphere total pressure. The diffusivity values are

D CO = 18.5 * 10⁻⁶ m²/s at 273 K, 1 atm

D CN = 19.2 * 10⁻⁶ m²/s at 288 K, 1 atm

The C is carbon monoxide, O is oxygen and N is nitrogen.

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Q. What is the molecular weight of Sulphur-dioxide?

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Q. The dimension of diffusion coefficient is given by

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Q. For what kind of mixtures Dᴀв=Dвᴀ holds?

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Q. In the expression for molar flux Nᴀ=(Nᴀ+Nв)Cᴀ/C – DᴀвdCᴀ/dz, the terms representing bulk flow and molecular diffusion are, respectively

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Q. Consider loss of ethanol vapor by diffusion from a half-filled open test tube. At what point in the diffusion path will the contribution of the bulk flow term to the molar flux be maximum?

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Q. A reaction 3A+2B+C=1.5D+E occurs in a reactor at steady state. What will be the value of the flux ratio Nᴀ/Nᴅ

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Q. For a component A of a mixture, concentration as a function of x is given:

Cᴀ=5e⁻¹⁰ˣ (x is in cm and Cᴀ in mol/liter)

Calculate the value of diffusion velocity (m/s) of the component A at the point x=0, if diffusivity of A in the mixture is 2.567*10⁻⁵m²/s.

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Q. A sheet of Fe 1.0 mm thick is exposed to an oxidizing gas on one side and a deoxidizing gas on the other at 725°C. After reaching steady state, the Fe membrane is exposed to room temperature, and the C concentrations at each side of the membrane are 0.012 and 0.075 wt%. Calculate the diffusion coefficient (m²/sec) if the diffusion flux is 1.4×10⁻⁸kg/m²-sec.

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Q. At which condition molar flux with respect to a stationary observer and with respect to an observer moving with molar average velocity?

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Q. Which among the following is the statement of the ‘Fick’s Law’?

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Q. The gas A diffuses through non-diffusing B from point 1 to point 2. The total pressure is 2atm and yᴀ₁=0.1 and yᴀ₂=0.Then the ratio (dPᴀ/dz)1/(dPᴀ/dz)2 is

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Q. In industries titanium is hardened through diffusion of carbon. The concentration of carbon at 1mm into the surface of the titanium slab is 0.25kg/m³ and at 3mm the concentration is 0.68kg/m³. The rate at which the carbon is entering into its surface is 1.27*10⁻⁹kg/m².s. Calculate the value of diffusion coefficient of carbon.

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Q. The mass transfer by convection can take place under how many conditions?

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Q. Lewis number is given by

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