Download Equilibrium Review worksheet

Equilibrium Acid Base Review
1. Hypochlorous acid may be produced by the following reaction
H2O(g) + Cl2O(g)
2 HOCl (g) Kc = 0.0090
Determine the concentrations of each reagent at equilibrium at 25 °C if the initial concentrations of
both water vapour and chlorine monoxide were 4.00 mol/L.
2. . Consider the following equilibrium
CO(g) + H2O(l)
CO2(g) + H2(g)
Kc = 5.0 at 650˚C
In a rigid 1.00 L laboratory reaction vessel, a technician places 1.00 mol of each of the four
substances involved in this equilibrium. The vessel is heated to 650 °C. Determine the equilibrium
amount concentrations of each substance, organizing your values in an ICE table. (Hint: use the
value of Kc to determine which side of the reaction is favored, and therefore which substances will
increase and which substances will decrease as equilibrium is established.)
3. Consider the reaction N2(g) +3 H2(g)
2 NH3(g), at equilibrium. If the system container volume
were to be suddenly decreased, the concentration of nitrogen gas in the system would immediately
A. increase, then decrease to a new constant value
B. remain unchanged, because the reaction is at equilibrium
C. increase, then remain steady at a new constant value
D. decrease, then remain steady at a new constant value
4a) Write the equilibrium law
expression for this reaction.
(1 mark)
b) Calculate the value of the
equilibrium constant (Kc) for this
reaction at 500K. (2 marks)
c) Are the products or reactants
favored for this reaction? Justify
your answer. (1 mark)
d) Use Modified Hess’s Law to calculate the enthalpy change for this reaction. (1 mark)
e) How will the position of the equilibrium be affected by an increase in temperature? Justify your answer.
(1 mark)
f) How will the value of the equilibrium constant be affected by in increase in the temperature. Justify your
answer. (1 mark)
Use the following information to answer question 2.
6a. Determine the concentration of hydrogen gas present in the flask at equilibrium. (2 marks)
b) Write the equilibrium law expression for the reaction, and determine the equilibrium constant for the
reaction at 90.0 °C. (2 marks)
c) Identify and describe three stresses that could be applied to the system that would shift the equilibrium to
the right. (3 marks)
d) Draw a graph showing
the change in the
concentration of the
reactants and products as
equilibrium is established.
concentration of
reactants and
products (mol/L)
point at which EQ
is established
time
Use the following information to answer the next question.
7. For each point in time, indicate shift in equilibrium, and then suggest a stress applied to the system that
could account for the change.
Time
Equilibrium Shift (left or Right)
Stress that explains the EQ Shift
W
Y
Z
8. Write chemical formulas and net ionic equations for the following overall reactions.
(a) Vinegar is used to neutralize a drain cleaner spill. (drain cleaner is sodium hydroxide
b) the addition of a small amount of a strong acid to a hydrogen phosphate ion–phosphate ion buffer
solution
c) the addition of phenolphthalein indicator to a strong base
d) sodium sulfate is dissolved in water
e) Baking soda solution (sodium hydrogen carbonate) is used to neutralize spilled rust remover
containing oxalic acid.
9. Hypochlorous acid may be produced by the following reaction
H2O(g) + Cl2O(g)
2 HOCl (g) Kc = 0.0090
Determine the concentrations of each reagent at equilibrium at 25 °C if the initial concentrations of
both water vapour and chlorine monoxide were 4.00 mol/L.
10. A 0.10 mol/L solution of the essential amino acid tryptophan has a measured pH of 5.19 at 25 °C.
Predict the percent ionization of this tryptophan solution, and the Ka value for aqueous
tryptophan. The molecular formula for tryptophan may be written as C 10H11N2COOH.
11. A 0.100 mol/L laboratory solution of sodium propanoate, NaC2H5COO(aq), has a measured pH of
8.95 at 25 °C. Calculate Kb for the propanoate ion.