COMPLETE
NOT YET (LT)
RETEST
TIERS 1 & 2 TIER 3 TIER 4 TIER 5 TIER 6
70% 75% 80% 85% 90% 96%
I. TIERS 1 & 2
1. Define a reversible reaction
2. Which statements are correct for a reaction at equilibrium?
I. The forward and reverse reactions both continue.
II. The rates of the forward and reverse reactions are equal.
III.The concentrations of reactants and products are equal.
A.
B.
C.
D.
I and II only
I and III only
II and III only
I, II and III
EXPLAIN YOUR ANSWER
3. Explain what a closed system is and why it is important for equilibrium.
II. TIER 3
1. What does a large magnitude of Kc indicate about the amount of product resulting from a chemical reaction that has reached equilibrium? Explain in detail.

2. The equation for one reversible reaction involving oxides of nitrogen is shown below:
N2O4(g) 2NO2(g) Δ H = +58 kJ
Experimental data for this reaction can be represented on the following graph: concentration
/ mol dm
–3
1.0
0.8
0.6
0.4
0.2
product reactant
0
2 4 6
Time / min
8 a. Write an expression for the equilibrium constant, K c, for the reaction.
10
A.
B.
C.
D. b. Explain the significance of the horizontal parts of the lines on the graph.
3. What changes occur when the temperature is increased in the following reaction at equilibrium?
Br2(g) + Cl2(g) 2BrCl(g) ∆ H
ο
= +14 kJ mol–1
Position of equilibrium
Shifts towards the reactants
Shifts towards the reactants
Shifts towards the products
Shifts towards the products
Value of equilibrium constant
Decreases
Increases
Decreases
Increases
EXPLAIN YOUR ANSWER

III. TIER 4
2.
1 Which of the following equilibria would not be affected by pressure changes at constant temperature?
A. 4HCl(g) + O
2
(g) 2H
2
O(g) + 2Cl
2
(g)
B. CO(g) + H
2
O(g) H
2
(g) + CO
2
(g)
C. C
2
H
4
(g) + H
2
O(g) C
2
H
5
OH(g)
D. PF
3
Cl
2
(g) PF
3
(g) + Cl
2
(g)
EXPLAIN YOUR ANSWER
.
Given the reaction between methane and water, determine how each stress would shift the equilibrium
CO(g) + 3H
2
(g)

H = +206 kJ CH
4
(g) + H
2
O(g) a.
Decreasing the temperature b.
Adding hydrogen gas c.
Removing carbon monoxide d.
Decreasing pressure

IV. TIER 5
1. The Haber method is used to produce ammonia by reacting hydrogen gas and nitrogen gas. In the reaction 93 kJ/mol of energy are given off. a.) Write the balanced equation for this reaction b.) What is the sign of ΔH c.) Write the equilibrium expression for this reaction d.) What catalyst is used in this reaction and why is it necessary? e.) In practice, typical conditions used in the Haber process involve a temperature of 500°C and a pressure of 200 atm. Explain how these conditions differ from what is expected and why these conditions are used rather than those that give the highest yield. f.) What percent of ammonia is produced in the initial reaction between hydrogen and nitrogen. g.) How does the process address the unused hydrogen and nitrogen not reacted? h.) Based on the fact that very little ammonia is produced in the initial reaction, what does this says about the magnitude of the equilibrium constant? EXPLAIN i.) Explain why this reaction is important for humanity j.) A chemist claims to have developed a new catalyst for the Haber process, which will increase the yield of ammonia. Is this feasible? EXPLAIN

.
V. TIER 6
1. LAB RESULTS
REACTION #1: CoCl
4
2 + 6 H
2
O  Co(H
2
O)
6
2+ + 4 Cl -
Cobalt chloride(CoCl
4
2 ) is bluish purple but will turn pink when water is added and the cobalt complex(Co(H
2
O)
6
2+ )is produced. a.)Adding hydrochloric acid to the above reaction at equilibrium will result in what type of color change. EXPLAIN b. When silver nitrate is added to the reaction, what happens? EXPLAIN c Is the above reaction endothermic or exothermic. Explain how you determined this in the lab.
2. LAB RESULTS
REACTION #2 Fe 3+ + SCN  Fe(SCN
6
) 3+ a. Iron(III) nitrate is yellow and potassium thiocyanate is clear. When they react together, the color of the resulting product is __________________________. b. When sodium fluoride is added to the equilibrium solution, what happened and why? c. Is the above reaction endothermic or exothermic. Explain how you determined this in the lab.BE
SPECIFIC
3. What will happen if CO2(g) is allowed to escape from the following reaction mixture at equilibrium?
CO2(g) + H2O(l) H+(aq) + HCO3
–
(aq)
A.
B.
The pH will decrease.
The pH will increase.
C.
D.
The pH will remain constant.
The pH will become zero.
EXPLAIN YOUR ANSWER
4. Give examples of how the concepts of gas laws, thermodynamic and kinetics were applied to the unit on equilibrium.