Integrated rate laws Knowledge-Based Practice

Questions

1. 1.

   A first-order reaction has a rate constant of $4.62 \times 10^{-3}\text{ s}^{-1}$ at a given temperature. What percentage of the reactant remains unreacted after 300 seconds?

   • A) 25%
   • B) 50%
   • C) 75%
   • D) 12.5%
2. 2.

   A plot of $1/[\text{A}]$ versus time for a chemical reaction yields a straight line with a slope of $0.20\text{ M}^{-1}\cdot\text{s}^{-1}$ and a y-intercept of $4.0\text{ M}^{-1}$. What is the initial half-life of this reaction?

   • A) 20 s
   • B) 10 s
   • C) 0.80 s
   • D) 0.050 s
3. 3.

   The decomposition of a substance on a solid catalyst follows zero-order kinetics with a rate constant of $2.5 \times 10^{-4}$ M·min$^{-1}$. If the initial concentration of the reactant is 0.120 M, how much time is required for its concentration to decrease to 0.045 M?

   • A) 180 min
   • B) 240 min
   • C) 480 min
   • D) 300 min
4. 4.

   The decomposition of cyclobutane is a first-order process with a rate constant of $2.0 \times 10^{-4}$ s-1 at a given temperature. How much time is required for the concentration of cyclobutane to decrease from 0.80 M to 0.20 M?

   • A) $1.7 \times 10^3$ s
   • B) $3.5 \times 10^3$ s
   • C) $6.9 \times 10^3$ s
   • D) $1.4 \times 10^4$ s
5. 5.

   A gaseous substance decomposes according to second-order kinetics with a rate constant of 0.025 M-1s-1. If the initial concentration of the reactant is 0.50 M, what is its concentration after 120 seconds?

   • A) 0.025 M
   • B) 0.10 M
   • C) 0.20 M
   • D) 0.33 M

Answers and step-by-step solutions appear after you finish the test.