Question

For the reaction aA+ bB → rR, which of the following is true?

(a) \(\frac{-r_A}{a}\)=\(\frac{-r_B}{b}\) ≤ \(\frac{r_R}{r} \)

(b) \(\frac{-r_A}{a}\) ≥\(\frac{-r_B}{b}\) ≤ \(\frac{r_R}{r} \)

(c) \(\frac{-r_A}{a}\)=\(\frac{-r_B}{b}\) ≤ \(\frac{r_R}{r} \)

(d) \(\frac{-r_A}{a}\)≤\(\frac{-r_B}{b}\) ≤ \(\frac{r_R}{r} \)

I had been asked this question in an interview.

My enquiry is from Reaction Rates in portion Basic Concepts of Chemical Reaction Engineering

Answer 1

Correct answer is (c) \(\frac{-r_A}{a}\)=\(\frac{-r_B}{b}\) ≤ \(\frac{r_R}{r} \)

The explanation is: The rates of degradation of reactants and formation of product are related to each other as \(\frac{-r_A}{a} = \frac{-r_B}{b} = \frac{r_R}{r} \), where a, b and c denote the stoichiometry. The rate of disappearance of any reactant in turn is the rate of formation of products.