5.02 Quiz: Factors Affecting Reaction Rates

Study Notes

Factors Affecting Reaction Rates

Some substances react more readily than others.
Concentration: increasing concentrations of reactants increases reaction rates due to more frequent collisions.
Surface Area: greater surface area allows particles to collide more frequently, increasing reaction rate.
Temperature: increasing temperature increases reaction rate by increasing kinetic energy of particles, leading to more frequent collisions.

Catalysts and Inhibitors

Catalyst: a substance that increases the rate of a chemical reaction without being consumed in the reaction.
Inhibitor: a substance that slows or prevents a reaction.
Heterogeneous catalyst: exists in a physical state different than that of the reaction it catalyzes.
Homogeneous catalyst: exists in the same physical state as the reaction it catalyzes.
Catalysts lower the activation energy, allowing more collisions to have sufficient energy to react.

Reaction Rate Laws

Reaction rate law: an experimentally determined mathematical relationship that relates the speed of a reaction to the concentrations of the reactants.
Rate law: expresses the relationship between the rate of a chemical reaction and the concentration of reactants, e.g. Rate = k[A].
Specific rate constant (k): a numerical value that relates the reaction rate and the concentrations of reactants at a given temperature.
Reaction order: defines how the rate is affected by the concentration of a reactant, e.g. first-order, second-order, etc.

Determining Reaction Order

Method of initial rates: determines reaction order by comparing the initial rates of a reaction carried out with varying reactant concentrations.
Initial rate: measures how fast the reaction proceeds at the moment when reactants are mixed.

Reaction Mechanisms

Reaction mechanism: the complete sequence of elementary steps that makes up a complex reaction.
Intermediate: a substance produced in one of the elementary steps and consumed in a subsequent elementary step.
Rate-determining step: the slowest elementary step in a complex reaction.
Complex reaction: a reaction with two or more elementary steps.

Description

Learn about the factors that influence reaction rates, including the nature of reactants, concentration, surface area, and catalysts. Understand how these factors impact the frequency of collisions between particles.