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Rate laws

Chemistry • Reaction Rates • Knowledge-Based • 5 questions

Rate laws Knowledge-Based Download PDF

Chemistry · Chemical Kinetics · Chemistry · Reaction Rates

5 Chemistry practice questions on Rate laws. Questions that assess core concepts and understanding.

Questions

  1. 1.

    A chemical reaction is experimentally determined to follow the rate law Rate=k[A]2[B]1/2[C]−1/2\text{Rate} = k [\text{A}]^2 [\text{B}]^{1/2} [\text{C}]^{-1/2}. What is the overall reaction order for this process?

    • A) 1
    • B) 2
    • C) 2.5
    • D) 3
  2. 2.

    For the reaction 2A+B→C2\text{A} + \text{B} \rightarrow \text{C}, doubling the concentration of A\text{A} at constant [B][\text{B}] has no effect on the reaction rate, whereas doubling [B][\text{B}] at constant [A][\text{A}] increases the rate by a factor of four. What is the rate law for this reaction?

    • A) Rate=k[B]2\text{Rate} = k[\text{B}]^2
    • B) Rate=k[A]2[B]\text{Rate} = k[\text{A}]^2[\text{B}]
    • C) Rate=k[A][B]2\text{Rate} = k[\text{A}][\text{B}]^2
    • D) Rate=k[B]\text{Rate} = k[\text{B}]
  3. 3.

    Which of the following statements is correct regarding the rate law for an overall chemical reaction?

    • A) The reaction orders are always equal to the stoichiometric coefficients in the overall balanced chemical equation.
    • B) The reaction orders must always be positive integers such as 1, 2, or 3.
    • C) The rate constant is an invariant value that remains unchanged when the temperature changes.
    • D) The reaction orders must be determined experimentally and cannot generally be deduced from the stoichiometric coefficients of the overall equation.
  4. 4.

    A reaction obeys the rate law Rate=k[X][Y]2\text{Rate} = k [\text{X}][\text{Y}]^2. If the concentration of X\text{X} is tripled and the concentration of Y\text{Y} is doubled at constant temperature, by what factor does the reaction rate increase?

    • A) By a factor of 6
    • B) By a factor of 12
    • C) By a factor of 18
    • D) By a factor of 24
  5. 5.

    For a chemical reaction described by the rate law Rate=k[A]2[B]\text{Rate} = k [\text{A}]^2 [\text{B}], what are the units of the rate constant kk when concentration is measured in mol⋅L−1\text{mol}\cdot\text{L}^{-1} and time in s\text{s}?

    • A) L2⋅mol−2⋅s−1\text{L}^2\cdot\text{mol}^{-2}\cdot\text{s}^{-1}
    • B) L⋅mol−1⋅s−1\text{L}\cdot\text{mol}^{-1}\cdot\text{s}^{-1}
    • C) mol2⋅L−2⋅s−1\text{mol}^2\cdot\text{L}^{-2}\cdot\text{s}^{-1}
    • D) s−1\text{s}^{-1}