Chemical Kinetics Quiz

Introduction to Chemical Kinetics

• Chemical Kinetics is a branch of physical chemistry concerned with the study of the speed of chemical reactions and the mechanism by which they occur.

• Reactions can be classified as homogeneous (occurring in one phase) or heterogeneous (occurring on the surface of a catalyst or container walls).

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

• Factors influencing the rate of a reaction include temperature, concentration of reactants, nature of reactants, catalysts, and radiation.

• An increase in temperature can significantly increase the rate of a reaction, while an increase in reactant concentration leads to increased collision frequency and thus increased reaction rate.

• The nature and strength of bonds in reactant molecules greatly influence the rate of transformation into products.

• Catalysts can enhance the speed of a chemical reaction by increasing the reaction rate.

• Some reactions increase in rate when specific wavelengths of radiation are absorbed by the reacting molecules, known as photochemical reactions.

• The order of a reaction is determined by the number of concentration terms on which reaction rate depends, with first and second order reactions being most common.

• Molecularity of a reaction is the number of molecules or atoms involved in a chemical change, with reactions being unimolecular, bimolecular, or termolecular.

• Zero order reactions have a rate that does not depend on the concentration of reactants, while first order reactions have a rate proportional to the concentration of the reactant.

• Second order reactions can be classified as either proportional to the square of the same reactant concentration or proportional to the product of two reactant concentrations. The rate equation can be used to determine the velocity constant and the fractional extent of the reaction over time.Kinetics of Chemical Reactions

• The rate of a chemical reaction is the change in the concentration of reactants or products per unit time.

• The rate law for a reaction gives the mathematical relationship between the rate and the concentrations of reactants.

• The order of a reaction is the sum of the powers to which the concentrations of the reactants are raised in the rate law.

• The rate constant is a proportionality constant that relates the rate of a reaction to the concentrations of reactants.

• The half-life of a reaction is the time required for half of the reactants to be consumed.

• The half-life of a second-order reaction is inversely proportional to the initial concentration of the reactant.

• The rate of a reaction involving two reactants is proportional to the product of their concentrations.

• Pseudo unimolecular reactions appear to follow first-order kinetics even though they involve more than one reactant.

• The rate constant has different units depending on the order of the reaction.

• The units of the rate constant for a reaction of nth order are moles/litre/sec (moles/litre)^n = litre^(n-1) moles^(1-n) sec^(-1).

• The velocity constant can be obtained from the slope of a plot of log[b(a-x)/a(b-x)] against time for a second-order reaction.

• The specific reaction rate for a first-order reaction is proportional to the concentration of the reactant.