For a chemical reaction $4 \mathrm{~A}+3 \mathrm{~B} \rightarrow 6 \mathrm{C}+9 \mathrm{D}$ rate of…

For a chemical reaction $4 \mathrm{~A}+3 \mathrm{~B} \rightarrow 6 \mathrm{C}+9 \mathrm{D}$ rate of formation of $\mathrm{C}$ is $6 \times 10^{-2} \mathrm{~mol} \mathrm{~L}^{-1} \mathrm{~s}^{-1}$ and rate of disappearance of $\mathrm{A}$ is $4 \times 10^{-2} \mathrm{~mol} \mathrm{~L}^{-1} \mathrm{~s}^{-1}$. The rate of reaction and amount of $B$ consumed in interval of 10 seconds, respectively will be:
  1. $1 \times 10^{-2} \mathrm{~mol} \mathrm{~L}^{-1} \mathrm{~s}^{-1}$ and $30 \times 10^{-2} \mathrm{~mol} \mathrm{~L}^{-1}$
  2. $10 \times 10^{-2} \mathrm{~mol} \mathrm{~L}^{-1} \mathrm{~s}^{-1}$ and $10 \times 10^{-2} \mathrm{~mol} \mathrm{~L}^{-1}$
  3. $1 \times 10^{-2} \mathrm{~mol} \mathrm{~L}^{-1} \mathrm{~s}^{-1}$ and $10 \times 10^{-2} \mathrm{~mol} \mathrm{~L}^{-1}$
  4. $10 \times 10^{-2} \mathrm{~mol} \mathrm{~L}^{-1} \mathrm{~s}^{-1}$ and $30 \times 10^{-2} \mathrm{~mol} \mathrm{~L}^{-1}$

Solution

$\begin{aligned} & \text { Explanation: } 4 \mathrm{~A}+3 \mathrm{~B} \longrightarrow 6 \mathrm{C}+9 \mathrm{D} \\ & \qquad \begin{aligned} \text { Rate of reaction } & =-\frac{1}{4} \frac{d[\mathrm{~A}]}{d t}=-\frac{1}{3} \frac{d[\mathrm{~B}]}{d t} \\ & =\frac{1}{6} \frac{d[\mathrm{C}]}{d t}=\frac{1}{9} \frac{d[\mathrm{D}]}{d t} \end{aligned} \end{aligned}$ Rate of reaction $=$ Rate of formation of $\mathrm{C}$. $\begin{aligned} \therefore \quad r & =\frac{1}{6} \frac{d[\mathrm{C}]}{d t}=\frac{1}{6} \times 6 \times 10^{-2} \\ & =1 \times 10^{-2} \mathrm{~mol} \mathrm{~L}^{-1} \mathrm{~s}^{-1} \end{aligned}$ Also, rate of reaction $=$ Rate of disappearance of $B$ $\begin{aligned} r & =-\frac{1}{3} \frac{d[\mathrm{~B}]}{d t}=\frac{d[\mathrm{~B}]}{d t}=3 \times r \\ & =3 \times 10^{-2} \mathrm{~mol} \mathrm{~L}^{-1} \mathrm{~s}^{-1} \end{aligned}$ Consumption of $B$ in 10 seconds $=3 \times 10^{-2} \times 10$ $=30 \times 10^{-2} \mathrm{~mol} \mathrm{~L}^{-1}$

Asked in: NEET 2022 (Phase 2)

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