Chemical Kinetics

These flashcards cover the fundamental concepts related to chemical kinetics, including definitions, theories, and important equations.

What is chemical kinetics?

It is the branch of physical chemistry that studies the speed of chemical reactions and the mechanisms by which they occur.

What are the two classifications of chemical reactions based on kinetics?

Homogeneous reactions (occur in one phase) and heterogeneous reactions (occur on the surface of a catalyst or container walls).

How is the rate of reaction defined?

The rate of reaction is the amount of chemical change occurring per unit time, usually expressed as the decrease in concentration of a reactant or the increase in concentration of a product.

What units are used to express the rate of reaction?

Moles/litre/second.

List factors that influence the rate of reaction.

Temperature, concentration of reactants, nature of reactants, catalysts, and radiation.

How does temperature affect reaction rates?

An increase of 10°C typically doubles or triples the rate of a chemical reaction.

What is the order of reaction?

The order of reaction is the number of concentration terms on which the reaction rate depends.

What is molecularity of a reaction?

It is the number of molecules or atoms involved in a chemical change, classified as unimolecular, bimolecular, or termolecular.

What is a zero order reaction?

A reaction whose rate does not depend on the concentration of reactants.

What characterizes first order reaction kinetics?

The rate of the reaction is directly proportional to the concentration of one reactant.

What is the Integrated rate equation for first order reactions?

C = Coe^(-Kt), where C is concentration at time t, Co is initial concentration, and K is the rate constant.

How is the half-life of a first order reaction defined?

t1/2 = 0.693/K, which is constant and independent of the initial concentration.

What defines a second order reaction?

The rate depends on either the square of the concentration of a single reactant or the product of the concentrations of two reactants.

How is the rate constant K defined for second order reactions?

K = 1/t * (a-x)/(x(a-x)), derived from the integrated rate laws.

What is a pseudo unimolecular reaction?

A reaction that appears to follow first order kinetics because one reactant's concentration is much larger than the other.

What does the Arrhenius equation summarize?

The relationship between the velocity constant K and temperature, which implies K = Ae^(-E/RT), with E being the activation energy.

What are the implications of activation energy in reactions?

It is the minimum energy required for reactants to undergo a chemical transformation.

What is the collision theory?

It explains how reactions occur through collisions between molecules and the factors that affect reaction rates.

How does a catalyst affect a reaction?

It increases the reaction rate without being consumed, by providing an alternative pathway with a lower activation energy.

What is the difference between order and molecularity in a reaction?

Order is an experimental value based on the reaction rate law, while molecularity refers to the number of species in the rate-determining step.