Worksheet: First-Order Integrated Rate Laws

In this worksheet, we will practice using the integrated rate law for a first-order reaction to calculate the rate constant and initial concentration.

Q1:

The decomposition of cyclobutane is a first-order reaction with a rate constant of 9.20×10 s−1 at 500C. Calculate, to 2 significant figures, the time taken for 80.0% of a sample of cyclobutane to decompose.

Q2:

Iodine-131 decays by 𝛽 emission with a rate constant of 0.138 d−1: 1315313154eIXe+e+̄𝜈. Calculate, to 2 significant figures, the time taken for 90.0% of a sample of iodine-131 to decay.

Q3:

Nitric oxide from aircraft exhaust reacts with atmospheric ozone, contributing to the depletion of the ozone layer, as shown in the equation. NO()+O()NO()+O()gggg322 This reaction is of the first order with respect to both reactants and has a rate constant of 2.20×10 L/mol⋅s. What is the instantaneous rate of reaction of NO if [NO] = 3.30×10 M and [O]3 = 5.90×10 M? Give your answer to two significant figures.

  • A 2 . 4 × 1 0 mol/L⋅s
  • B 2 . 5 × 1 0 mol/L⋅s
  • C 4 . 3 × 1 0 mol/L⋅s
  • D 7 . 7 × 1 0 mol/L⋅s
  • E 3 . 3 × 1 0 mol/L⋅s

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