Chemistry: Chapter 14

Study Notes

Chemical Reaction Basics

Activation energy is the minimum energy required for a chemical reaction to occur.
High activation barrier means only a few molecules have sufficient kinetic energy, resulting in a slower reaction.
Temperature increase leads to an increase in reaction rate.

Transition State and Arrhenius Equation

The transition state is a hypothetical species between reactants and products on a reaction profile.
The Arrhenius equation shows that the rate constant increases with increasing temperature and decreasing activation energy.
The equation is: k = Ae^-Ea/RT, and ln k = (-Ea/RT) + ln A.

Reaction Mechanism

A reaction mechanism is a step-by-step description of a chemical reaction.
Each step is an elementary process, and the mechanism must be consistent with stoichiometry and experimentally determined rate law.
Elementary processes can be unimolecular or bimolecular, and are reversible.

Catalysis

Catalysis is an alternative reaction pathway with lower energy.
It increases the rate of reaction, reduces activation energy, and completes the reaction in less time.

Rate of Reaction

Rate of reaction = ΔM / Δt, where ΔM is the change in concentration of products.
Rate of reaction = rate of disappearance of reactants = rate of appearance of products.

Rate Law

The rate law is Rate = k [A]^m [B]^n, where k is the rate constant.
The overall order of reaction = m + n +…, and m and n are not related to a and b.

Types of Rate Laws

Zero-Order Rate Law: Rate = k, where the sum of exponents is 0.
First-Order Rate Law: Rate = k [A], where the sum of exponents is 1.
Second-Order Rate Law: Rate = k [A]^2, where the sum of exponents is 2.

Half-Life

The half-life (t½) is the time taken for one-half of a reactant to be consumed.
For a first-order reaction, the half-life is constant and independent of initial concentration.

Description

Test your understanding of rates of reaction, rate laws, and the factors that affect them. This quiz covers the concepts of rate of formation, rate of reaction, and rate constant, including zero-order rate laws and how they are affected by temperature, concentration, and catalysts.