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Effectiveness factor (E) of a catalyst pellet is defined as, E = (actual rate within pore of catalyst/rate if notsnowed by pore diffusion) Effectiveness factor for a first order reaction is given by (where, T = Thiele modulus)
A spherical porous catalyst particle of radius R is subjected to reactant A which reacts to form B by a zero order surface reaction A → B. Film mass transfer resistance is negligible and pore diffusion of A is rate controlling. The effectiveness factor of the catalyst is reported as $$\frac{7}{8}$$. Which of the following statement is true?
Consider the following statements regarding the importance of diffusion and choose the correct answer:
1. The exchange of gases takes place by the principle of dependent diffusion
2. The process of diffusion is involved in transpiration of water vapours
3. The ions are absorbed by the simple diffusion during passive salt uptake
4. Diffusion is an effective means of transport of substances over a very short distance and helps in the translocation of food materials
Diffusion through grain boundaries is very fast and is called short-circuit diffusion. Assertion: Their contribution to overall diffusion is negligible.
Match List 1 with List 2 and choose the correct answer form the code given below: List 1 (Cultural diffusion) List 2 (Definition) (a) Relocative  1.Upward/downward movement of dispersal through a system of classes or centres (b) Hierarchical Diffusion  2. When acceptance of or information about an innovation spreads throughout the society (c) Expansion Diffusion  3. When expansion affects almost uniformly to all individuals and areas from a source region (d) Contagious Diffusion  4. Geographical transfer of culture traits by movements of people across space
In a gas mixture of hydrogen and oxygen, steady state equimolar counter diffusion is occurring at a total pressure of 100 kPa and temperature of 20°C. If the partial pressures of oxygen at two planes 0.01 m apart, and perpendicular to the direction of diffusion are 15 kPa and 5 kPa, respectively and the mass diffusion flux of oxygen in the mixture is 1.6 * 10–5 kmol/m2.sec, calculate the molecular diffusivity for the system. For equimolar counter current diffusion:
Thiele modulus is used for the solid catalyst.
Thiele modulus will increase with the decrease of the size of the catalyst.
For a first order chemical reaction in a porous catalyst, the Thiele modulus is 10. The effectiveness factor is approximately equal to
The effectiveness factor for large value of Thiele modulus $${\text{L}}\sqrt {{\text{K}}/{{\text{D}}_1}} $$   of a solid catalysed first order reaction is equal to (where, L = length of the reactor, cm, D1 = diffusion co-efficient, cm2/second)