AP Chemistry 5.1-5.3 Rate Laws

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What is a rate law?

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A rate law is an equation that relates the rate of a chemical reaction to the concentration of its reactants. It is typically expressed in the form R = k[A]^m[B]^n, where R is the rate, k is the rate constant, and m and n are the reaction orders with respect to reactants A and B.

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What is the unit of the rate constant (k) for a second-order reaction?

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The unit of the rate constant (k) for a second-order reaction is M^-1 s^-1.

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How do you determine the order of a reaction with respect to a reactant?

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The order of a reaction with respect to a reactant can be determined experimentally by observing how the rate of reaction changes as the concentration of that reactant is varied, typically using the method of initial rates.

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What is the significance of the rate exponent in a rate law?

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The rate exponent indicates the power to which the concentration of a reactant is raised in the rate law, reflecting how changes in that concentration affect the reaction rate.

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What is the rate law for the reaction 2ClO2(aq) + 2OH-(aq) -> ClO3(aq) + ClO2-(aq) + H2O(l)?

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The rate law for this reaction is R = k[ClO2][OH-].

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What is the method of initial rates?

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The method of initial rates is an experimental technique used to determine the rate law of a reaction by measuring the initial rate of reaction at different concentrations of reactants.

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What does a zero-order reaction imply about the concentration of reactants?

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In a zero-order reaction, the rate of reaction is constant and does not depend on the concentration of the reactants; changes in concentration do not affect the rate.

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What is the relationship between the rate constant (k) and temperature?

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The rate constant (k) generally increases with an increase in temperature, as described by the Arrhenius equation, which shows the dependence of k on temperature and activation energy.

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How can you determine the rate constant (k) from experimental data?

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The rate constant (k) can be determined from the rate law and experimental data by rearranging the rate law equation and substituting known values of rate and concentrations.

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What is the effect of a catalyst on the rate of a reaction?

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A catalyst increases the rate of a reaction by providing an alternative reaction pathway with a lower activation energy, without being consumed in the reaction.