Question

Instantaneous rate of reaction for the reaction $3A+2B$ $\to 5C$ is ______ .

• A. $+\frac{1}{3}\frac{d[A]}{dt}=-\frac{1}{2}\frac{d[B]}{dt}=+\frac{1}{5}\frac{d[C]}{dt}$
• B. $-\frac{1}{3}\frac{d[A]}{dt}=-\frac{1}{2}\frac{d[B]}{dt}=+\frac{1}{5}\frac{d[C]}{dt}$
• C. $-\frac{1}{3}\frac{d[A]}{dt}=+\frac{1}{2}\frac{d[B]}{dt}=-\frac{1}{5}\frac{d[C]}{dt}$
• D. $+\frac{1}{3}\frac{d[A]}{dt}=-\frac{1}{2}\frac{d[B]}{dt}=-\frac{1}{5}\frac{d[C]}{dt}$

Answer 1

Answer: (B)

Rate of disappearance of the reactant is equal to the rate of appearance of the product by relation shown below:
For example,
$aA+bB\to cC$
For this the Instantaneous rate of the reaction will be given as:
$-\frac{1}{a}\frac{d[A]}{dt}=-\frac{1}{b}\frac{d[B]}{dt}=+\frac{1}{c}\frac{d[C]}{dt}$
Thus for the reaction: $3A+2B\to 5C$ the instantaneous rate of the reaction will be given as:
$-\frac{1}{3}\frac{d[A]}{dt}=-\frac{1}{2}\frac{d[B]}{dt}=+\frac{1}{5}\frac{d[C]}{dt}$