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IMU CET Kinetics — practice questions — page 2

Explore 71 free Kinetics questions in IMU CET Chemistry. Open each question or exercise to read its content, reference answers and available explanation.

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Kinetics questions and exercises with answers

Showing questions 31–60 of 71.

What is characteristic of the rate of a zero order reaction?Read the answer and worked solution →Which expression gives the half-life of a first order reaction?Read the answer and worked solution →Which expression gives the half-life of a simple second order reaction?Read the answer and worked solution →Which expression gives the half-life of a zero order reaction?Read the answer and worked solution →For which reaction order is the half-life independent of the starting concentration?Read the answer and worked solution →Hydrogen peroxide decomposes by a first order path with a half-life of 2.16 x 10^4 s. What is the rate constant?Read the answer and worked solution →Iodine-131 decays by a first order process with a rate constant of 0.138 per day. What is its half-life?Read the answer and worked solution →Cyclobutane decomposes by a first order path with k = 9.2 x 10^-3 per second. How long does it take for 80.0 percent of a sample to decompose?Read the answer and worked solution →Butadiene dimerises by a second order path with k = 5.76 x 10^-2 L/mol/min. Starting at 0.200 M, what concentration remains after 10.0 min?Read the answer and worked solution →Ammonia decomposes on a hot tungsten wire and also on hot quartz. Which pair of orders applies?Read the answer and worked solution →A reaction is second order in A with k = 2.42 L/mol/s. If the initial concentration of A is 0.500 mol/L, what is the half-life?Read the answer and worked solution →A steroid with a first order half-life of 42 days is taken once. How long until only one sixty-fourth of the dose remains?Read the answer and worked solution →According to collision theory, which two conditions must a collision meet to give products?Read the answer and worked solution →What is formed when reactants collide with the right orientation and enough energy?Read the answer and worked solution →How easy is it to isolate or identify a transition state during a reaction?Read the answer and worked solution →How does collision theory account for faster rates at higher concentration?Read the answer and worked solution →In the Arrhenius equation, what value does the gas constant R take?Read the answer and worked solution →What does the frequency factor A in the Arrhenius equation describe?Read the answer and worked solution →A plot of ln k against 1/T is drawn for a reaction. What does its slope equal?Read the answer and worked solution →For the decomposition of HI, k is 3.52 x 10^-7 L/mol/s at 555 K and 3.95 x 10^-2 L/mol/s at 781 K. What is the activation energy?Read the answer and worked solution →For a gas phase decomposition, k is 1.66 L/mol/s at 650 K and 7.39 L/mol/s at 700 K. What is the activation energy?Read the answer and worked solution →The rate of a reaction doubles for every 10 degree Celsius rise. How much faster does it run at 95 degrees than at 25 degrees?Read the answer and worked solution →What is a reaction mechanism?Read the answer and worked solution →What distinguishes an elementary reaction from an overall reaction?Read the answer and worked solution →What is an intermediate in a reaction mechanism?Read the answer and worked solution →What does the molecularity of an elementary reaction count?Read the answer and worked solution →What rate law does a unimolecular elementary step obey?Read the answer and worked solution →Why are termolecular elementary steps uncommon?Read the answer and worked solution →Which step in a multistep mechanism sets the rate of the overall reaction?Read the answer and worked solution →For 2NO plus 2H2, doubling [H2] doubles the rate while doubling [NO] quadruples it. What is the overall order?Read the answer and worked solution →

Worked practice questions

What is characteristic of the rate of a zero order reaction?

  1. It rises steadily as products build up
  2. It halves each time concentration halves
  3. It stays constant whatever the concentration
  4. It depends on the square of concentration
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Correct answer: C. It stays constant whatever the concentration

1. For zero order the differential rate law is rate = k[A]^0, which is simply rate = k. 2. There is no concentration term left in the expression. 3. So the rate holds the same value however much or little reactant is present. 4. Halving the rate when concentration halves is first order behaviour instead. _Source: OpenStax Chemistry (CC BY 4.0), Ch 12 "Kinetics", section 12.4 Integrated Rate Laws_

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Which expression gives the half-life of a first order reaction?

  1. t(1/2) = 1/(k[A]0)
  2. t(1/2) = [A]0/(2k)
  3. t(1/2) = 2k/[A]0
  4. t(1/2) = 0.693/k
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Correct answer: D. t(1/2) = 0.693/k

1. Start from ln([A]0/[A]) = kt and set [A] equal to half of [A]0. 2. The ratio inside the logarithm becomes 2, and ln 2 is 0.693. 3. So t(1/2) = 0.693/k for a first order reaction. 4. Note that [A]0 has cancelled out, which is why this half-life does not depend on the starting concentration. 5. The forms 1/(k[A]0) and [A]0/(2k) belong to second order and zero order respectively. _Source: OpenStax Chemistry (CC BY 4.0), Ch 12 "Kinetics", section 12.4 Integrated Rate Laws_

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Which expression gives the half-life of a simple second order reaction?

  1. t(1/2) = 1/(k[A]0)
  2. t(1/2) = 0.693/k
  3. t(1/2) = [A]0/(2k)
  4. t(1/2) = k/[A]0
Show answer and solution

Correct answer: A. t(1/2) = 1/(k[A]0)

1. Start from 1/[A] minus 1/[A]0 equal to kt and set [A] equal to half of [A]0. 2. Then 2/[A]0 minus 1/[A]0 equals k times t(1/2), so 1/[A]0 equals k times t(1/2). 3. Rearranged, t(1/2) = 1/(k[A]0). 4. The starting concentration survives here, so this half-life does depend on how much reactant you began with. 5. The form 0.693/k is the first order result and cannot be used for a second order reaction. _Source: OpenStax Chemistry (CC BY 4.0), Ch 12 "Kinetics", section 12.4 Integrated Rate Laws_

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