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Half-Life quiz Flashcards

Half-Life quiz
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  • What is the half-life of a radioactive isotope if the decay follows a first-order reaction?
    For a first-order reaction, the half-life is constant and calculated using the formula T1/2 = ln(2)/k, where k is the rate constant.
  • How does the half-life of a zero-order reaction change as the initial concentration decreases?
    In a zero-order reaction, the half-life decreases as the initial concentration decreases because it is directly proportional to the initial concentration.
  • What happens to the half-life of a second-order reaction as the initial concentration decreases?
    In a second-order reaction, the half-life increases as the initial concentration decreases because it is inversely proportional to the initial concentration.
  • How is the half-life of a first-order reaction related to the initial concentration?
    The half-life of a first-order reaction is independent of the initial concentration and remains constant throughout the reaction.
  • What is the formula for calculating the half-life of a zero-order reaction?
    The half-life of a zero-order reaction is calculated using the formula T1/2 = [A]0 / (2k), where [A]0 is the initial concentration and k is the rate constant.
  • Why are radioactive decay processes typically modeled as first-order reactions?
    Radioactive decay processes are modeled as first-order reactions because their half-life is constant and independent of the initial concentration, providing consistent decay rates.
  • What is the relationship between half-life and the rate constant in a first-order reaction?
    In a first-order reaction, the half-life is inversely proportional to the rate constant, as given by the formula T1/2 = ln(2)/k.
  • How does the half-life of a second-order reaction change over time?
    The half-life of a second-order reaction increases over time as the concentration of the reactant decreases.
  • What is the significance of the constant ln(2) in the half-life formula for first-order reactions?
    The constant ln(2) in the half-life formula for first-order reactions represents the natural logarithm of 2, approximately 0.693, which is used to calculate the time required for half of the substance to decay.
  • How much of a radioactive parent isotope will remain after three half-lives have passed?
    After three half-lives, 1/8 (or 12.5%) of the original radioactive parent isotope will remain.