Reaction Mechanisms and Rate Laws

This chemistry lecture covers reaction mechanisms and rate laws, explaining how reactions occur in steps and the role of intermediates. It discusses the rate determining step and how to derive rate laws from reaction mechanisms. The lecture includes example problems to illustrate these concepts.

Why is it unlikely for three reactant particles to collide simultaneously to form a product?

• Because simultaneous collisions are rare.

• Because they are too small to collide.

• Because they are in different phases.

• Because they repel each other.

What is an intermediate in a reaction mechanism?

• A byproduct that is not used in the reaction.

• A catalyst that speeds up the reaction.

• A product that is formed and consumed during the reaction.

• A reactant that starts the reaction.

What determines the speed of a reaction in a multi-step mechanism?

• The step with the highest energy.

• The slowest step.

• The step with the most reactants.

• The fastest step.

How can we verify if a proposed reaction mechanism is correct?

• By checking if the products are colorful.

• By comparing the derived rate law with experimental data.

• By ensuring the reactants are in the same phase.

• By measuring the temperature change.

What is the role of the rate constant 'K' in a rate law?

• It determines the color of the reactants.

• It is a measure of the reaction's speed.

• It indicates the reaction's equilibrium.

• It shows the reaction's temperature.

What should be done if an intermediate appears in the rate-determining step?

• Ignore it in the rate law.

• Substitute it with the concentration of starting reactants.

• Use it as a catalyst.

• Replace it with a product.

In the given problem, why can't N2O2 be used directly in the rate law?

• Because it is a reactant.

• Because it is an intermediate.

• Because it is a catalyst.

• Because it is a product.

What is the significance of setting the rates of forward and reverse reactions equal in a fast equilibrium?

• To calculate the temperature change.

• To determine the color of the solution.

• To find the concentration of intermediates.

• To measure the pressure of the system.

How is the overall rate law affected if the slow step involves an intermediate?

• The intermediate is added to the products.

• The intermediate is used as a catalyst.

• The intermediate is replaced with starting reactants.

• The intermediate is ignored.

What is the final step in deriving a rate law when intermediates are involved?

• Adding more reactants.

• Substituting intermediates with starting reactants.

• Increasing the temperature.

• Decreasing the pressure.