Chemical Kinetics

The speed at which reactants are converted into products.

A chemical reaction's rate is dependent on the concentration of reactants raised to a specific power (the order).

The sum of the exponents in the rate law. It tells you how much the rate increases with a change in concentration.

A substance that speeds up a reaction without being consumed in the process.

The minimum energy that molecules must possess to undergo a reaction.

A chemical reaction where the slowest step determines the overall rate of the reaction. In a multi-step reaction, the slowest step acts as a bottleneck, limiting how quickly the reaction can proceed.

A chemical reaction mechanism where the rate law is based on the rate of the slowest step, even if it's not the first step in the mechanism.

A step in a chemical reaction mechanism that involves the collision of two molecules. The rate of a bimolecular step depends on the concentrations of both reactants.

A series of elementary steps that describe the overall course of a chemical reaction. Each step represents an individual molecular event, and the mechanism provides a detailed picture of how reactants are transformed into products.

The exponent of a reactant's concentration in the rate law. It indicates how the rate changes when the concentration of that reactant is altered.

The constant of proportionality in the rate law. It reflects the intrinsic speed of the reaction at a given temperature.

The sum of the individual reaction orders for all reactants. It indicates the overall sensitivity of the rate to changes in reactant concentrations.

A method used to determine the order of a reaction by examining how the rate changes as reactant concentrations are varied systematically. Experimentally measuring the initial rate at different starting concentrations of reactants.

The rate of a reaction is directly proportional to the concentration of the reactant raised to the power of 1. Doubling the concentration doubles the rate.

The rate of a reaction is directly proportional to the square of the concentration of the reactant. Doubling the concentration quadruples the rate.

The rate of a reaction is independent of the concentration of the reactant. The rate remains constant even if the concentration of the reactant changes.

For a gas, the rate of reaction increases with pressure. This effect is similar to how reaction rate is affected by concentration.

The rate of a reaction is influenced by the available surface area of the reactants. A larger surface area allows for more collisions between molecules, leading to a faster reaction. This is why powdered magnesium reacts faster with acid than a magnesium block.

For a reaction to occur, molecules must collide with the correct orientation. This means they must align in a specific way so that the reactive parts contact each other. Complex molecules have lower chances of colliding with the correct orientation, hence they often have slower reaction rates.

Temperature directly affects molecular speed, and therefore the rate of reaction. Higher temperatures lead to faster moving molecules, causing more frequent and energetic collisions.

The energy barrier that reactants must overcome in order to form products. It represents the energy required to break and form bonds during the reaction.

This distribution describes the number of molecules at different energy levels in a sample. It shows that at a given temperature, only a small fraction of molecules have enough energy to overcome the activation energy and react.

Increasing the temperature increases the number of molecules with sufficient energy to overcome the activation energy. This results in a faster reaction rate.

The order of a reaction with respect to a specific reactant is determined by how much the rate changes when the concentration of that reactant is doubled. If the rate doubles, the reaction is first order with respect to that reactant. If the rate quadruples, the reaction is second order with respect to that reactant.

The overall order of a reaction is the sum of the individual orders with respect to each reactant. For example, a reaction that is first order with respect to A and second order with respect to B has an overall order of 3.

SN1 reactions are unimolecular, meaning they are first order with respect to the substrate. The rate-determining step is the dissociation of the substrate, which occurs in two steps: the formation of a carbocation intermediate and the reaction of the carbocation with the nucleophile.

SN2 reactions are bimolecular, meaning they are first order with respect to the substrate. The rate-determining step is the concerted attack of the nucleophile on the substrate, which occurs in one step.

The rate law for an elementary reaction is determined directly from the stoichiometry of the reaction. The rate law for the elementary step is written as the product of the rate constant and the concentrations of the reactants raised to their stoichiometric coefficients.

A measure of how fast a chemical reaction proceeds. It quantifies the change in concentration of reactants or products over time.

The Arrhenius equation is a mathematical expression that describes the relationship between the rate constant of a reaction, activation energy, and temperature.

A factor that determines the frequency of collisions between molecules at a given temperature, independent of the activation energy. It represents the maximum rate of reaction.

A biological catalyst, typically a protein, that speeds up specific biochemical reactions in living organisms.

The number of molecules involved in a single step of a multi-step reaction mechanism. It is determined by the stoichiometry of the elementary reaction step.

A reaction step that involves the simultaneous collision of three or more molecules.

A reaction step in which the rate of the reaction is directly proportional to the product of the concentrations of the reactants raised to their respective stoichiometric coefficients.