SCH 4UI
Unit 4 Equilibrium Review… Chapters 7 and 8
Concepts covered; define the conditions for equilibrium, Keq expression, calculation of Keq using ICE charts,
Keq vs Qeq, LeChatelier’s Principle, Entropy, Gibbs Free Energy, Acids and Bases Basics, Arrhenius’s theory,
Bronsted-Lowry theory, pH and pOH, Kw, Ka and Kb, percent dissociation, polyprotic acids, buffers, neutralization
reactions and salts produced affect pH, Ksp, Ksp vs Qsp
-Additional Chapter Review Questions
Ch7 page482, #1-12, 14-20, 23,34,35,36,40,63,64
Ch8 page559, #1-14,22,29,32,36,38,64,68,69
MORE Practice Questions….
QUICKS:
TEST: mc, quicks and 5 short answer calc questions
-make sure you practice so you will be able to
complete the test in the 75min given!
a) What is the pH at equivalence point if HCl neutralizes LiOH? ___________
b) At the equivalence point for a titration of acetic acid and NaOH, will the solution be acidic or
basic? Circle
c) If Ka for acetic acid is 1.8X10-5, what is the Kb for the conjugate? ________
d) If Qsp is greater than Ksp will a precipitate form? _______
e) On a concentration vs time graph, when the concentrations of the reactants are equal, is the
system at equilibrium? Yes OR No
Short Answer
1. Predict the shift of the reaction H2(g) + I2(g)  2HI(g) + 23kJ has reached equilibrium:
i) concentration of H2 is decreased. ____________
ii) concentration of I2 is increased. _____________
iii) concentration of HI is decreased. _____________
iv) an increase in pressure.
______________
v) an increase in temperature.
______________
2. Hydrogen iodide, HI, decomposes at moderate temperatures according to the equation
2HI(g)  H2(g) + I2(g)
The amount of I2 in the reaction mixture can be determined from the intensity of the violet colour
of I2; the more intense the colour, the more I2 in the reaction vessel. When 4.00 mol HI was
placed in a 5.00 L vessel at 458oC, the equilibrium mixture was found to contain 0.442 mol I2.
What is the value of Kc for the decomposition of HI at this temperature?
3. Nicotinic acid (niacin) is a monoprotic acid with the formula HC6H4NO2. A solution that is 0.012M
in nicotinic acid has a pH of 3.39 at 25oC. What is the acid-ionization constant, Ka, for this acid
at 25oC? What is the degree of ionization of nicotinic acid in this solution?
4. Morphine, C17H19NO3, is administered medically to relieve pain. It is a naturally occurring base,
or alkaloid. What is the pH of a 0.0075 M solution of morphine at 25oC? Kb = 1.6 x 10-6 @ 25oC.
5. Calculate the molarity of Ba(OH)2, if 47 mL of 0.50 M HCl was required to neutralize the base.
6. By experiment, it is found that 1.2 x 10-3 mol of lead(II)iodide, PbI2, dissolves in 1 L of aqueous
solution at 25oC. What is the Ksp at this temperature?
7. 15g of Sodium methanoate, NaHCOO and 20g of methanoic acid were added to 750ml of water
to create a buffer system. Determine the pH of the solution.
8. 25ml of 0.10 M of NaOH is added to 500 ml of 0.0001 M of cobalt (II) chloride. Does a
precipitate form? Include a balanced chemical equation for the formation of the possible
precipitate.