AP Chemistry - Kinetics Flashcards

Vocabulary flashcards for AP Chemistry kinetics.

Kinetics

The study of the speeds, or rates, of chemical reactions.

Factors Affecting Reaction Rates

Physical state of reactants, concentration of reactants, temperature, and the presence of a catalyst.

Collision Theory

Collisions must have enough energy and correct orientation to overcome coulombic attractions between each bonded atom and shared electrons.

Reaction Rate

The change in concentration over time. Rate =  [ ] /  Time. Rates are (+) for products and a (–) sign is used for disappearance of reactants.

Rate and Stoichiometry Equation

Rate = − (1/a) ([A]/t) = − (1/b) ([B]/t) = (1/c) ([C]/t) = (1/d) ([D]/t) for the reaction aA + bB cC + dD

Differential Rate Law

Shows the relationship between the reaction RATE and the CONCENTRATIONS of reactants. Rate = k[reactant1]^m[reactant2]^n….

Orders of Reaction

0 order = change in conc has no effect on rate; 1 order = change in conc has a direct effect; 2 order = change in conc has an exponential effect

Rate Constant (k)

k = Rate / ([reactant1]^m[reactant2]^n….). Units depend on the overall order of the reaction.

Overall Order of Reaction

Sum of the orders of the reactants. Overall order = m+n+…… for Rate = k[reactant1]^m[reactant2]^n….

Integrated Rate Law

Relates the concentration of reactants to time. The form of the equation depends on the order of the reaction.

Zero Order Integrated Rate Law

[A] = −kt + [Ao]

First order Integrated Rate Law

ln[A] = −kt + ln [A0]

Second Order Integrated Rate Law

1/[A] = kt + 1/[A0]

Half-Life of a First-Order Reaction

t1/2 = 0.693 / k

Reaction Mechanism

The sequence of bond making and bond breaking steps that occurs during the conversion of reactants to products.

Elementary Step

A single step in a reaction mechanism.

Molecularity

The number of molecules involved in an elementary step.

Intermediate

A species that is formed in one step of a reaction mechanism and consumed in a subsequent step. NOT a reactant or product.

Catalyst

A substance that increases the rate of a reaction without being consumed in the reaction.

Rate-Determining Step

The slowest step in a reaction mechanism; determines the overall rate of the reaction.

Catalysis

The increase in the rate of a chemical reaction due to the participation of a catalyst.