Chemical Kinetics and Reaction Rates

The rate of change of concentration of a reactant or product in a chemical reaction over time.

A mathematical expression that shows the relationship between the rate of reaction and the concentrations of the reactants.

The rate of a reaction is directly proportional to the concentration of the reactants. Higher concentration means more collisions and a faster rate.

The rate of a reaction is increased by increasing the surface area available for reactions. More contact points lead to more collisions.

Increasing temperature causes molecules to move faster and have more collisions with sufficient energy to react, speeding up the reaction.

A substance that speeds up a reaction without being consumed. It provides an alternative lower-energy pathway for the reaction.

The minimum energy required for a reaction to occur.

A constant that relates the rate of a reaction to the concentrations of the reactants. It's specific to a given reaction.

A reaction that appears to be first order, even though it actually has a higher order, due to the presence of a reactant in large excess, making its concentration practically constant.

A method for determining the rate law of a reaction where the initial rate is measured for different initial concentrations of reactants, while keeping other reactants in excess.

The power to which a reactant's concentration is raised in the rate law, indicating its influence on the overall reaction rate.

A reaction where the rate is determined primarily by the concentration of one reactant, whose concentration changes significantly while others remain essentially constant.

A technique in determining the rate law where the concentration of one reactant is kept constant while the concentrations of other reactants are varied.

Determining the rate law by integrating the differential rate equation, comparing the integrated equation with experimental data to identify the best fit.

The sum of the powers to which each reactant concentration term is raised in the rate law. It indicates how the reaction rate changes with changes in reactant concentrations.

An equation that expresses the relationship between the rate of a reaction and the concentrations of reactants. It's determined experimentally, not from the balanced chemical equation.

A rate law that appears to be first order due to the assumption that the concentration of one reactant is constant, even though it's not truly constant.

A reaction whose rate is independent of the concentration of the reactants. It's rare but can occur when a reaction is limited by another factor, like the rate of surface coverage.

A reaction whose order is a fraction, indicating a more complex relationship between the rate and concentration.

A method of determining the order of a reaction by observing the pattern of successive half-lives. For example, the half-life of a zeroth-order reaction is halved with each successive half-life, while the half-life of a first-order reaction remains constant.

In a zeroth-order reaction, the concentration of the reactant decreases linearly with time. The rate of reaction is independent of the initial concentration of the reactant. The plot of [X] vs t will be linear with a slope of -k and intercept [X]o.

The time it takes for the concentration of a reactant to decrease to half its initial value. It is a useful concept to understand the rate and kinetics of a reaction.

In a first-order reaction, the concentration of the reactant decreases exponentially with time. The rate of reaction is directly proportional to the initial concentration of the reactant. The plot of ln[X] vs t will be linear with a slope of -k and intercept ln[X]o.

In a second-order reaction, the concentration of the reactant decreases with the square of time. The rate of reaction is proportional to the square of the initial concentration of the reactant. The plot of 1/[X] vs t will be linear with a slope of 2k and intercept 1/[X]o.

In a third-order reaction, the concentration of the reactant decreases with the cube of time. The rate of reaction is proportional to the cube of the initial concentration of the reactant. The plot of 1/[X]^2 vs t will be linear with a slope of 2k and intercept 1/[X]o^2.

The half-life of a second-order reaction is inversely proportional to the initial concentration of the reactant. This means that the half-life decreases as the initial concentration increases.

The half-life of a third-order reaction is inversely proportional to the square of the initial concentration of the reactant. This means that the half-life decreases even faster than in a second-order reaction as the initial concentration increases.