Asked in PMC Practice Test 8 (2021) 2021Moderate

Half-life period for a first-order reaction is independent of which of the following?

Correct answer: B. Initial Concentration of the compound

  • A. Conditions of temperature
  • B. Initial Concentration of the compound
  • C. Presence of Catalyst
  • D. All of these

Explanation

Half-life ( t1/2t1/2 ) is a timescale on which the initial population is decreased by half of its original value notice that, for first-order reactions, the half-life is independent of the initial concentration of reactant, which is a unique aspect to first-order reactions. The practical implication of this is that it takes as much time for [A] to decrease from 1 M to 0.5 M as it takes for [A] to decrease from 0.1 M to 0.05 M.

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About Order of Reaction

Reaction order shows how the rate depends on the concentration of each reactant, as expressed in the rate law. Coverage includes zero, first and second-order reactions, integrated rate equations, half-life, units of rate constants and the distinction between overall order and molecularity.

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