Note: Encircle the correct choices.
1. A sample of 1 mol of 𝑁2𝑂4 was placed in an empty 1 dm3 container and allowed to reach equilibrium
according to the following equation. 𝑁2𝑂4(𝑔) ↔ 2𝑁𝑂2(𝑔). What will be the Kc for this reaction.
A. 2𝑥/( 1 – 𝑥 )2
B. 2𝑥/( 1 – 𝑥 )
C. 4𝑥/(1 – 𝑥 )
D. 4𝑥2/ (1 – 𝑥 )
2. In which gaseous equilibrium more products will be formed by increasing pressure?
A. N2(g) + 3H2(g) ↔ 2NH3(g)
B. PCl5( g) ↔ PCl3(g) + Cl2(g)
C. N2(g) + O2(g ) ↔ 2NO(g)
D. H2(g) +I2(g) ↔ 2HI(g)
3. Nitrogen dioxide decomposes on heating according to the following equation.
2 NO2(g) ↔ 2NO(g) + O2(g)
When 4 mol of nitrogen dioxide were put into a 1 dm3 container and heated to a constant temperature,
the equilibrium mixture contained 0.8 mol of oxygen. What is the value of the equilibrium constant, Kc, at
the temperature of the experiment?
𝐴.
0.82 𝑥 0.8
42
𝐵.
1.6 𝑥 0.8
2.42
𝐶.
1.62 𝑥 0.8
42
𝐷.
1.62 𝑥 0.8
2.42
Q:1. Consider the equilibrium: N2O4(g) ↔ 2NO2(g)
∆H = +58.1 KJmol-1
i. Write an expression for the Kc for this reaction, giving its units.
[8]
ii. 1 mol of N2O4 was introduced in to a vessel of volume 10.0dm3 at 70°C. At equilibrium, 50% of
N2O4(g) had dissociated. Calculate Kc.
iii. If the temperature is increased, giving your reasons, how the equilibrium position would change.
iv. Explain what you would do to increase the degree of dissociation of N2O4(g) at constant temperature
Q.2(a) Ethanoic acid, 𝐶𝐻3𝐶𝑂2𝐻, reacts with ethanol, 𝐶2𝐻5𝑂𝐻, to produce ethyl ethanoate and water. The
reaction is an example of dynamic equilibrium.
𝐶𝐻3𝐶𝑂2𝐻(𝑙) + 𝐶 2𝐻5𝑂𝐻(𝑙)  𝐶𝐻3𝐶𝑂2𝐶 2𝐻5(𝑙) + 𝐻2𝑂(𝑙)
A mixture of 6.0 g of ethanoic acid and 6.0 g of ethanol was added to 4.4 g of ethyl ethanoate and the
overall mixture allowed to reach equilibrium. It was found that 0.040 mol of ethanoic acid was present in
the equilibrium mixture.
(i) Calculate the number of moles of each compound, both initially and at equilibrium. Also calculate the
equilibrium constant, Kc, for the reaction.
[4]
(b) What will be the effect of following conditions on the (a) position of equilibrium (b) value of equilibrium
constant?
(i)
When we increase the concentration of ethyl ethanoate.
[4]
(ii). Increase in pressure.