Learning Objectives:

• Understand how to calculate the conversion of a reactant in a chemical reaction, which represents the extent to which the reactant is transformed into products.

• Conversion (X) measures the extent to which a reactant is transformed into products during a chemical reaction.
• It is calculated as the ratio of the change in the moles of reactant to the initial moles of reactant.
• X = (Initial moles of reactant - Moles of reactant at any time) / Initial moles of reactant.

Solved Example: 9292-01

If $\tau$ = 5 s, first order rate constant, k = 0.25 sec$^{-1}$ and the number of tanks, N is 5, then the conversion is?

A. 87.45%

B. 33%

C. 75%

D. 67.2%

Correct Answer: D

Solved Example: 9292-02

If the conversion of a first-order liquid phase reaction occurring in a CSTR is 75%, molar feed rate is 5 mol/min, the rate of the reaction is 5 𝑚𝑜𝑙/𝑙𝑖𝑡𝑟𝑒.𝑚𝑖𝑛 then the volume of the reactor (in litre) is?

A. 0.33

B. 0.4

C. 0.75

D. 0.5

Correct Answer: C

Solved Example: 9292-03

A reaction of first order takes 10 minutes to achieve 50% conversion. The conversion achieved after 20 minutes is:

A. 0.5

B. 0.75

C. 0.87

D. 0.9

Correct Answer: B

Learning Objectives:

• Learn to calculate the yield of a chemical reaction, which quantifies the amount of desired product produced in a reaction.

• Yield represents the actual amount of the desired product formed in a reaction.
• Yield can be calculated by determining the moles or mass of the desired product produced.
• Yield (%) = (Actual yield / Theoretical yield) x 100%.

Solved Example: 9290-01

A reaction is known to have a percent yield of 80%. It the actual yield is 25 grams, what was the expected yield?

A. 3.2 gram

B. 19 gram

C. 31.25 gram

D. 190 gram

Correct Answer: C

Solved Example: 9290-02

The final concentration of product is related to the yield as:

A. Final concentration = Yield × Reactant fed

B. Final concentration = Yield / Reactant fed

C. Final concentration = Yield × Reactant converted

D. Final concentration = Yield / Reactant fed

Correct Answer: C

Solved Example: 9290-03

The reaction yield is defined as the ratio of:

A. Moles of reactant reacted to the moles of product formed

B. Moles of product formed to the moles of reactant reacted

C. Moles of desired product formed to the moles of undesired material formed

D. Moles of product formed to the moles of reactant fed

Correct Answer: B

Learning Objectives:

• Define selectivity and learn to calculate it, representing the ratio of the yield of a specific desired product to the total yield of all products.

• Selectivity is the ratio of the yield of a specific product to the total yield of all products in a reaction.
• It measures how efficient a reaction is in producing the desired product.
• Selectivity (%) = (Yield of desired product / Total yield of all products) x 100%.

Solved Example: 9291-01

Selectivity in parallel reactions is defined as the ratio of:

A. Moles of desired product formed to the moles of undesired material formed

B. Moles of undesired product formed to the moles of desired material formed

C. Moles of product formed to the moles of reactant consumed

D. Moles of reactant consumed to the moles of product formed

Correct Answer: A