Kinetics Lecture Activity

Chapter 16: Kinetics: Rates and Mechanisms of Chemical Reactions Lecture activity: Reaction Rate: Concentration, physical state , and temperature influence the reaction rate. True/False I n a faster reaction, the reactants are converted into products at a higher speed . True/False Give the following chemical equation: 2NO? ? N?O? Express the rate in terms of NO? Express the rate in terms of N?O? What is the relationship between these two expressions? Rate Law: The rate law is determined experimentally. True/False 1 st order rate is directly proportional to the concentration of one reactant k[A]. True/False Why is zero order rate independent of concentration? Rate= k[A]m[B]n Experiment Initial rate (M.min-1) [A]/M [B]/M 1 0.02196 0.175 0.175 2 0.02196 0.175 0.058 3 0.00732 0.058 0.058 Given the information above what is the order of the reaction with respect to [A] (what is n)? th order 1 st order 2 nd order 3 rd order Integrated Rate Law: The integrated rate law is used to determine the amount of reactant or product present after a period of time . True/False The half-life of a first-order reaction does not depend on the initial concentration of the reactant. True/False A first-order reaction has a rate constant of 2.75 × 10 ? ²s ? ¹. Calculate: The half-life of the reaction The time required for 75% of reactant to decompose The concentration of reactant remaining after 150 seconds if initial concentration was 0.55 M" Collision Theory and Concentration: Collision must occur with enough energy to break bonds and this energy is the Activation energy. True/False Molecular orientation determines whether a reaction will occur when molecules collide. True/False. Consider a reaction: 2A + B ? Products If the concentration of A is doubled while keeping B constant: How does this affect the collision frequency between A molecules and B molecules? What is the theoretical effect on reaction rate? Explain using collision theory Reaction Mechanism: In a reaction mechanism, the slowest step determines the overall rate of reaction. True/False An intermediate is produced in one step and consumed in another step of a mechanism. True/False. Given the following mechanism: Step 1: NO? + NO? ? N?O? (fast, reversible) Step 2: N?O? + F? ? 2NO?F (slow) Identify the intermediates. Write the overall balanced equation. Write the rate law based on the mechanism. Identify the rate-determining step.