Exams › JEE Advanced › Chemistry

For the reaction A + B -> product, the following experimental data is observed: Exp 1: [A]0 = 0.02 mol/L, [B]0 = 0.03 mol/L, Rate = 4 * 10⁻³ mol/L/s Exp 2: [A]0 = 0.04 mol/L, [B]0 = 0.06 mol/L, Rate = 1.6 * 10⁻² mol/L/s Exp 3: [A]0 = 0.01 mol/L, [B]0 = 0.06 mol/L, Rate = 4 * 10⁻³ mol/L/s Which of the following statements is/are correct?

1. The given reaction may be an elementary reaction
2. The value of the rate constant is 6.67 mol⁻¹ L s⁻¹
3. The given reaction may be a complex (multi-step) reaction
4. If the volume of the container in experiment 1 is doubled, the rate becomes 10⁻³ mol/L/s

Correct answer: The value of the rate constant is 6.67 mol⁻¹ L s⁻¹

Solution

Comparing Exp 1 and Exp 3: [B] is doubled from 0.03 to 0.06 but [A] is halved from 0.02 to 0.01; rate stays the same at 4e-3. Comparing Exp 1 and Exp 2: both [A] and [B] are doubled; rate increases 4 times (from 4e-3 to 1.6e-2). If rate = k[A]^x[B]^y, then 4 = 2^x * 2^y. Separately, from Exp1 vs Exp3: doubling [B] and halving [A] gives rate ratio 1, so (1/2)^x * 2^y = 1 => y = x. Then 4 = 2^(2x) => x = 1, y = 1. Rate = k[A][B], second order overall. From Exp 1: k = 4e-3 / (0.02 * 0.03) = 6.67 mol⁻¹ L s⁻¹. An elementary A+B reaction would be second-order, consistent; it could also be a complex reaction with the same rate law. Doubling volume halves concentrations: new rate = 6.67 * 0.01 * 0.015 = 10⁻³ mol/L/s.

Related JEE Advanced Chemistry questions

• The given equation implies that:
• Given that C₁ represents the starting concentration of A, and C₁, C₂, and C₃ denote the concentrations of A, B, and C respectively at a specific time t, which equation can be used to calculate the values of k₁ and k₂?
• In the reaction M → N, the rate at which M is consumed becomes 8 times faster when the concentration of M is doubled. What is the reaction order with respect to M?
• For the reaction A(g) + B(g) ⇌ AB(g), the activation energy for the reverse reaction is greater than that for the forward reaction by 2RT (in J mol⁻¹). If the forward reaction's pre-exponential factor is four times that of the backward reaction, what is the magnitude of ΔG⁰ (in J mol⁻¹) at 300 K?
• A gaseous compound X decomposes into gaseous products Y and Z according to first-order kinetics (X -> Y + Z). Initially only X is present. Ten minutes after the reaction begins, the partial pressure of X is 200 mmHg and the total pressure of the mixture is 300 mmHg. What is the rate constant for this reaction?
• A catalyst is added to a first-order reaction at 500 K, causing its rate to become 2.718 times the original rate. The activation energy with the catalyst present is 4.15 kJ/mol. What was the activation energy before the catalyst was introduced? (Given: R = 8.3 J/K/mol, ln(2.718) = 1)

⚔️ Practice JEE Advanced Chemistry free + battle 1v1 →