SCH4U
EQUILIBRIUM UNIT TEST REVIEW
CHAPTER 7
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Be able to identify various systems and conditions that lead to equilibrium.
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E.g. a puddle of water.
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E.g. a jar of water.
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Precipitates and ions.
Homogeneous vs. Heterogeneous equilibrium.
Three physical processes that reach equilibrium.
Four conditions applying to all equilibrium systems.
Favourable vs. Unfavourable change
Gibbs free energy – meaning of variables (∆G, ∆H, ∆S, and T).
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Meaning of positive/negative ∆G, ∆S, ∆H. Understand how changing the variables affects the likelihood of a reaction to
be favourable.
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Understand table 7.1
Law of chemical equilibrium, and kf = kr
Differ between equilibrium constants Keq and Kc.
Define Kc using a general equilibrium equation.
Writing equilibrium expressions.
Calculating equilibrium constant, Kc.
Measuring Equilibrium Concentration (pg. 339)  if given table with missing values, can complete it.
Solving an Equilibrium Expression by taking the root of both sides.
Solving equilibrium Expression using a Quadratic equation.
Qualitatively Interpreting the Equilibrium Constant. (K>1, K=1, K<1). Reactions going to completion (K>1010 ) or not happening
(K<10-10 ).
The approximation method (determining if x is negligible).
The reaction quotient, Qc.
Qualitatively interpreting the relationship between Qc and Kc (the direction of shift to attain equilibrium): e.g. if Qc < Kc, which way
does the equilibrium need to shift to attain equilibrium?
Le Chatelier’s Principle: be able to define the principle, as well as describe the effects of different variables on different reactions at
equilibrium.
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In terms of the following, 1) which way will equilibrium shift to re-establish equilibrium and 2) what will the effect be on
Kc.
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Common ion effect: adding/removing substances
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Temperature: increasing/decreasing when dealing with endothermic/exothermic reactions.
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Volume and Pressure change: increasing/decreasing.
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Adding a catalyst
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Adding an inert gas
Understand table 7.2
Texbook Questions
 Pg. 327, #2, #4
 Pg. 333, #3, #4
 Pg. 336, #3, 4
 Pg. 338, #7
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Pg. 349, #16, 17, 18
Pg. 355, #28
Pg. 366, #30, 31, #33
Pg. 370, #1, 2, 3
Supplementary Questions
1.
At a certain temperature, Kc = 4.0 for the following reaction.
2HF(g) ⇄ H2(g) + F2(g)
A 1.0 L reaction vessel contained 0.045 mol F2(g) at equilibrium. What was the initial amount of HF in the reaction vessel?
2.
Hydrogen bromide decomposes at 700 K.
2HBr(g) ⇄ H2(g) + Br2(g)
Kc = 4.2 x 10-9
0.090 mol of HBr is placed in a 2.0 L reaction vessel and heated to 700 K. What is the equilibrium concentration of
each gas? (Do not ignore x).
3.
At a certain temperature, the value of Kc for the following reaction is 3.3 x 10-12.
2NCl3(g) ⇄ N2(g) + 3Cl2(g)
A certain of nitrogen trichloride, NCl3(g) is put in a 1.0L reaction vessel at this temperature. At equilibrium, 4.6 x 10-4 mol of
N2(g) is present. What amount of NCl3(g) was placed in the reaction vessel.
CHAPTER 8
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Describe the physical properties of acids and bases.
Describe the differences between Arrhenius and Bronsted-Lowry theories of acids and bases. (Table pg.
380).
Identify conjugate acid-base pairs.
Solve problems involving strong acids and strong bases.
Define monoprotic and polyprotic acids.
Strong Acids: Binary and Oxoacids  define. Strong Bases: define. (Understand Fig. 8.6)
Ion Product constant of water, Kw.
 Using it to find the concentrations of conjugate acids/bases.
Acids and bases as defined by inequalities of ion concentrations, e.g. [H 3O+] > [OH-]
Calculate pH, pOH, [H3O+], [OH-] (logs and antilogs)
Acid and Base dissociation constants: define using general equations.
Percent dissociation
Calculations that involve polyprotic acids.
Know the components of a buffer.
Be able to describe how a buffer solution works.
Identify the three kinds of titration curves.
Textbook Questions
 Pg. 382, #1, 2, 4
 Pg. 386, #5, 6.
 Pg. 390 # 10, 11
Supplementary Questions
1.
Calculate the pH of the following solutions:
a. 3.1 mol/L KOH(aq)
b.
30.0 mL of 4.50 mol/L HBr(aq) diluted to 100.0 mL.
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Pg. 392, #14, 15, 16.
Pg. 403, #1, 3
c.
18.6 mL of 2.60 mol/L HClO4(aq) added to 24.8 mL of 1.92 mol/L NaOH(aq).
d.
16.5 mL of 1.50 mol/L H2SO4(aq) added to 12.7 mL of 5.50 mol/L NaOH(aq).
2.
Calculate the pH of a sample of vinegar that contains 0.83 mol/L acetic acid. What is the percent
dissociation of the vinegar?
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Calculate the pH of a 1.0 x 10-2 mol/L solution of butanoic acid, a monoprotic acid.
(Ka = 1.51 x 10-5).
4.
Hydrosulfuric acid, H2S(aq), is a weak diprotic acid that is sometimes used in analytical work. Calculate the
pH and [HS- (aq)] of a 7.5 x 10-3 mol/L solution.
5.
A 4.5 x 10-3 mol/L solution of morphine has a pH of 9.93. Calculate Kb for morphine.
6.
Kb for ammonia, NH3, is 1.8 x 10-5. Kb for trimethylamine, (CH3)3N, is 6.5 x 10-5. Which is the stronger acid,
NH4+ or (CH3)3NH+?
CHAPTER 9
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Acidic and basic properties of salts: determining if solution will be acidic or basic depending on the salt.
Calculating pH at equivalence.
Choosing an appropriate indicator depending on equivalence point.
The solubility product constant: define
Determining a Solubility Product Constant.
The effect of a common ion on solubility (qualitative and calculations).
Comparing the ion product, Qsp, to the solubility product, Ksp to determine the formation of a
precipitate. (e.g. Qsp > Ksp).
Using the Solubility guidelines to predict the formation of a precipitate.
Textbook Questions
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Pg. 424, #1, 2, 3
Pg. 429, #2, 7.
Pg. 432, #10
Pg. 433, #14
Pg. 439, # 22 (refer to sample problem for help!)
Pg. 442, # 6
Pg. 446, #31
Pg. 447, #36
Pg. 451, # 2.
Supplementary Questions
1.
0.025 mol/L benzoic acid is titrated with 0.025 mol/L sodium hydroxide solution. Calculate the pH at
equivalence.
2.
Part way through a titration, 2.0 x 10 mL of 0.10 mol/L sodium hydroxide has been added to 3.0 x 10 mL
of 0.10 mol/L hydrochloric acid. What is the pH of the solution.
3.
Ksp for zinc iodate, Zn(IO3)2, is 3.9 x 10-6 at 25 degrees Celcius. Calculate the molar solubility of Fe(OH) 3.
SUPPLEMENTARY UNIT REVIEW
Pg. 458
# 1-11.
# 12, 14, 15, 16, 23, 26, 30, 37, 40.
Review all questions on your tests!