Mass Transfer Mock Test 1

1. A binary mixture of oxygen and nitrogen with partial pressures in the ratio 0.21 and 0.79 is contained in a vessel at 300 K. If the total pressure of the mixture is 1 * 10 ⁵ N/m², find mass fraction of oxygen

2. For a component A of a mixture, concentration as a function of x is given:
C_A=5e^-10x (x is in cm and C_A 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.

3. Which number forms the connecting link between the velocity and temperature profiles?

4. Which number forms the connecting link between the velocity and concentration profiles?

5. For what kind of mixtures D_AB=D_BA holds?

6. Sherwood number is given by

7. 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.

8. 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

9. In which of the following conditions mass transfer will occur spontaneously? C and z is concentration and distance respectively.

10. 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?