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CHEM 142 Exam 2 Study Guide – Spring 2012
I. Chapter 13: Kinetics (Integrated Rate Laws and Half-Life only)
Key concepts:
1) Integrated rate laws
2) Half-life
Problem-solving: A copy of Table 13.2 Rate Law Summary Table will be provided during the exam.
1) Work on Example 13.3 and Practice 13.3 (p. 574), Example 13.4 and Practice 13.4 (p. 575), Example
13.5 and Practice 13.5 (p. 575), and Example 13.6 and Practice 13.6 (p. 579).
II. Chapter 14: Chemical Equilibria
Concepts and skills that you need to know/possess:
1) Chemical equilibrium
Definition
A condition where the rates of forward and reverse reaction are equal
No net change in concentration of reactants and products
Does not mean concentrations of reactants and products are equal
Explain the difference between reaction rates (kinetics) and equilibrium (thermodynamics) – see
lecture notes
Dynamic process (Review Question 2, p. 650)
Relate to reversibility of chemical reactions
2) Equilibrium constant expression, K (or K
eq
or K
c
; Review Questions 21-24, 33-34, p. 651-
652)
Write equilibrium constant expressions for:
Gaseous reactants and products (Use K
P
instead of K)
Heterogeneous reactions (don’t include solids (s) and liquids(l))
Other chemical reactions, such as those involving species in aqueous (aq) solutions
Meaning of large K (>1), small K (< 1) and K = 1 in terms of direction of equilibrium and
relative abundance (or concentration) of reactants and products (Review Questions 23-24)
3) LeChâtelier’s principle (Review Questions 61, 63, 65, 67-70, p. 654)
State LeChâtelier’s principle in terms of disturbance to a system in equilibrium
Explain the effect of each of the following changes to an equilibrium system:
Concentration of reactants or products
Temperature (treat “heat” as reactant or product depending on whether the reaction is
exothermic or endothermic)
Pressure (only affects gases; relate to change in volume)
4) Calculating K given the equilibrium concentrations of all species (Review Questions 35-38 (but only for
the lowest temperature in 37-38), p. 652)
5) Calculating K from initial concentrations and at least one equilibrium concentration (Example 14.6 and
Review Questions 41-44, pp. 652-653)
6) Calculating equilibrium concentrations when K is given and the equilibrium concentrations of all but one
species (Example 14.8, p. 632 and Review Questions 51, 53 & 55, p. 653)
