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ChemistryNumerical+3Question 35 of 54

JEE Advanced 2019 · Paper 1, Chemistry question 17

Consider the kinetic data given in the following table for the reaction A+B+C→Product\ce{A + B + C -> Product}.

The rate of the reaction for [A] = 0.15 mol dm⁻³, [B] = 0.25 mol dm⁻³ and [C] = 0.15 mol dm⁻³ is found to be Y×10−5Y\times10^{-5} mol dm⁻³ s⁻¹. The value of YY is ______

Initial-rate data for A + B + C → Product.
Answer and worked solution

Official answer: 6.7

Orders, from the initial rates.

  • Experiments 1 → 2: doubling [B] leaves the rate unchanged, so zero order in B.
  • Experiments 1 → 3: doubling [C] doubles the rate, so first order in C.
  • Experiments 1 → 4: multiplying [A] by 1.5 multiplies the rate by 1.5, so first order in A.

Rate constant.
k=6.0×10−50.2×0.1=3.0×10−3 dm3 mol−1s−1.k=\frac{6.0\times10^{-5}}{0.2\times0.1}=3.0\times10^{-3}\ \mathrm{dm^3\,mol^{-1}s^{-1}}.

New rate.
r=3.0×10−3×0.15×0.15=6.75×10−5.r=3.0\times10^{-3}\times0.15\times0.15=6.75\times10^{-5}.
Answer: 6.75 (key: 6.70 to 6.80)

Topics:Order and molecularityRate of reaction and rate law
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