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Chemistry · 2025 · 3 marks
CBSE 2025 · Region 5 · Set 1 · Q23
For the reaction A + B → Products, the following initial rates were obtained at various initial concentrations of reactants: Determine the order of…
For the reaction $\displaystyle \mathrm{A}+\mathrm{B} \rightarrow$ Products, the following initial rates were obtained at various initial concentrations of reactants :
Determine the order of the reaction with respect to A and B and overall order of the reaction.
| Sl. No. | $\displaystyle [\mathrm{A}] / \mathrm{mol} \mathrm{L}^{-1}$ | $\displaystyle [\mathrm{B}] / m o l ~ \mathrm{L}^{-1}$ | Initial rate $\displaystyle / \mathrm{mol} \mathrm{L}^{-1} s^{-1}$ |
| $\displaystyle 1$ | $\displaystyle 0 \cdot 1$ | $\displaystyle 0 \cdot 1$ | $\displaystyle 0.05$ |
| $\displaystyle 2$ | $\displaystyle 0 \cdot 2$ | $\displaystyle 0 \cdot 1$ | $\displaystyle 0 \cdot 10$ |
| $\displaystyle 3$ | $\displaystyle 0 \cdot 1$ | $\displaystyle 0 \cdot 2$ | $\displaystyle 0.05$ |
Marking-scheme solution
Rate=k[A]x[B]y
Eq.1 Rate1=k($\displaystyle 0.1$)x($\displaystyle 0.1$)y=$\displaystyle 5.0$ x $\displaystyle 10$-$\displaystyle 2$
Eq.2 Rate2=k($\displaystyle 0.2$)x($\displaystyle 0.1$)y=$\displaystyle 1.0$ x $\displaystyle 10$-$\displaystyle 1$
Eq.3 Rate3=k($\displaystyle 0.1$)x($\displaystyle 0.2$)y=$\displaystyle 5.0$ x $\displaystyle 10$-$\displaystyle 2$
𝑘 × $\displaystyle 0.2$𝑥 × $\displaystyle 0.1$𝑦
𝑘 × $\displaystyle 0.1$𝑥 × $\displaystyle 0.1$𝑦
Hence x=$\displaystyle 1$
𝑘 × $\displaystyle 0.1$𝑥 × $\displaystyle 0.2$𝑦
𝑘 × $\displaystyle 0.1$𝑥 × $\displaystyle 0.1$𝑦
Hence y= $\displaystyle 0$
Rate=k[A]$\displaystyle 1$[B]$\displaystyle 0$
Overall order=$\displaystyle 1$
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