Exam Chapters and Topics:
13.1-13.2 Reaction Rates
13.3-13.4 Integrated Rate Law
13.4-13.6 Effect of Temperature, Catalysts, Reaction Mechanisms II
21.1-21.2 Radioactive Particles, Rates of Decay
14.1-14.2 Introduction to Equilibrium, Reaction Quotient
14.3 LeChatelier’s Principle
14.4-14.5 Equilibrium Calculations
Chapter 13
I. Reaction Rates
Chemical Kinetics: The study of the rates of chemical reactions
These reactions occurs when a reactant species interact w/ each other and form a new species called products.
Rate of Reaction
Rate: Change in unit per time; The rate of reaction is measured in terms of a change in concentration per unit in time
Rate =
Square brackets are used to describe molar concentrations; the reactant concentration decreases during the reaction so [reactant] is negative. The product increases in concentration so [product] is positive.
THE RATE OF REACTION IS ALWAYS EXPRESSED AS A POSITIVE NUMBER, REGARDLESS!
The rate of reaction is not typically constant, it changes over the course of the reaction so time is very important
To be more accurate in calculating the rate of reaction subtract or add based on observations to determine the rate.
The common units used to express reaction rates are M/s (Molarity/time); also written as (mol/L)/ s or mol/(L*s) or mol L-1s-1
Average Rate: when a rate is measured over a time interval; not useful for general calculations just specific intervals
Instantaneous Rate: The slope of the tangent to the curve of the concentration versus time graph; this is used for all chemical applications
Rate Reaction and Stoichiometry
The rates at which reactions are consumed and products are formed depend on stoichiometry of the reaction.
Ex. 2HBr(g) H2(g) + Br2(g) *For every 2 mol of HBr that react, 1 mol of each product forms. The same 2:1 ratio applies to the rate of the reaction as well. For example if the concentration of HBr decreases at