For the reaction A + B → P.If [B] is doubled at constant [A], the rate of reaction doubled. If [A] is triple and [B] is doubled, the rate of reaction increases by a factor of 6. Calculate the rate law equation.

Q.19 For the reaction A + B → P.
If [B] is doubled at constant [A], the rate of reaction doubled. If [A] is triple and [B] is doubled, the rate of reaction increases by a factor of 6. Calculate the rate law equation.

Doubtly Asked 29 Oct 2026 Board exam · March 2024 hsc 12th Save WhatsApp Report

1 answer

Best answer

Answer: Rate = k[A][B]

Let rate \(R_1 = k[\mathrm{A}]^x[\mathrm{B}]^y\).

Case 1: [B] doubled at constant [A]: \(\dfrac{R_2}{R_1} = \dfrac{k[\mathrm{A}]^x(2[\mathrm{B}])^y}{k[\mathrm{A}]^x[\mathrm{B}]^y} = 2^y = 2\ \Rightarrow\ y = 1\)

Case 2: [A] tripled and [B] doubled: \(\dfrac{R_3}{R_1} = 3^x \times 2^y = 6\)

With y = 1: \(3^x \times 2 = 6 \Rightarrow 3^x = 3 \Rightarrow x = 1\)

Rate law: \(\text{Rate} = k[\mathrm{A}]^1[\mathrm{B}]^1\); the reaction is first order in A, first order in B and second order overall.

Doubtly AI · 29 Oct 2026 AI-generated · not yet verified Report

Was this answer helpful?

For the reaction A + B → P.If [B] is doubled at constant [A], the rate of reaction doubled. If [A] is triple and [B] is doubled, the rate of reaction increases by a factor of 6. Calculate the rate law equation.

1 answer

Your answer