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.