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The half-life for a first order reaction depends on the starting concentration.

a. True
b. False

User Asymptote
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Final answer:

The half-life of a first-order reaction is independent of the concentration of the reactants.

The statement that the half-life for a first-order reaction is dependent on the starting concentration is incorrect.

Step-by-step explanation:

The half-life of a first-order reaction is independent of the concentration of the reactants. The rate at which a first-order reaction occurs depends only on the rate constant. The concentration of the reactant decreases by a constant factor with each half-life, regardless of the initial concentration.

The statement that the half-life for a first-order reaction is dependent on the starting concentration is incorrect. The half-life for a first-order reaction is constant and independent of the reactant concentration, while for second-order and zeroth-order reactions, the half-life does depend on the concentration.

The assertion that the half-life for a first-order reaction depends on the starting concentration is false. For a first-order reaction, the half-life is independent of the concentration of the reactants, meaning it remains constant under given reaction conditions. The half-life for a first-order reaction can be expressed using the equation: t₁₂ = 0.693/k, where k is the rate constant for the reaction. This is what distinguishes first-order reactions from zeroth- and second-order reactions, where the half-lives do depend on the reactant concentrations.



Unlike first-order reactions, for a second-order reaction, the half-life (t₁₂) is inversely proportional to the initial concentration of the reactant. As the reaction proceeds and the reactant concentration decreases, the half-life of a second-order reaction increases. Additionally, the rate constant of a second-order reaction cannot be calculated directly from the half-life without knowing the initial concentration.



In contrast, for zero-order reactions, although the half-life is also inversely proportional to the rate constant, it increases as the initial concentration increases. This also highlights the unique nature of the first-order reaction half-life, which maintains its constancy regardless of such changes.

User ScampMichael
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