SS2: Chemistry Theory Questions – Chemical Equilibrium

Question 1:

a. What is meant by an equilibrium system?

b. State the effect of increase in pressure on the equilibrium position of each of the following reactions:
i. 2CO_[g] + O_2[g] ⇌ 2CO_2[g]
ii. N_2[g] + O_2[g] ⇌ 2NO_[g]
iii. Pcl_5[g] ⇌ Pcl_3[g] + Cl_2[g]

c. What is the difference between a closed system and an open system?

d. Consider the reaction represented by the equation
2SO_2[g] + O_2[g]  \(\overset{V_2O_5}{ \rightarrow} \)2SO₃       ∆H = -188KJ

Write an expression for the equilibrium constant.

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Question 2:

a. State Le Chatelier’s principle

b. Consider the following equilibrium reactions
PCl_5[g] ⇌ PCl_3[g] + Cl_2[g]     ∆H =+xKJmol^-1
i. Write an expression for the equilibrium constank ‘Kc’
ii. What would happen to the equilibrium position when the:
– Pressure of the system is reduced
– Temperature of the system is increased
– Concentration of the reactant is increased

c. List three properties of a system that is in a state of chemical equilibrium

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Question 3:

a. Name the processes used for the industrial production of 
i. Ammonia
ii. Tetraoxosulphate(VI)acid

b. Give three reaction conditions for the conversion of sulphur(vi)oxide in contact process

c. The conversion below represent the stages in the industrial production of Tetraoxosulphate(vi)acid
SO₂ + O₂ ⇌ X + conc. H₂SO₄ →   Y + Z   → H₂SO₄
Identify X, Y, Z

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Question 4:

a. The free energyEnergy is the ability to do work. Energy exists in several forms such as heat, kinetic or mechanical energy, light, potential energy, and electrical energy. Units of Energy: The SI unit... More change for the reaction 
2Cu_[S] + 2NO_[g] →  2CuO_[S] + N_2[g] is -300KJ at 300K. What is the equilibrium constant for the reaction?
[R = 0.00831 atm dm³ k^-1]

b.  Consider the following equilibrium reaction:
3Fe_[S] + 4H₂O_[g] ⇌ Fe₃O_4[S] + 4H_2[g]      ∆H = -150KJmol^-1
Explain the effect of the following factors on the position of equilibrium
i. Decrease in temperature
ii. Increase in pressure
iii. Removal of  hydrogen

c. List three factors that affect a system in chemical equilibrium

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Question 5:

a. Given the following equilibrium mixture of gases at 500°C, where ∆H is negative
2CO_[g] + O_2[g] ⇌ 2CO_2[g]

What will be the effect of: 
i. Adding more O₂ at constant pressure?
ii. Increasing the temperature?
iii. Adding a catalyst
iv. Adding a base to absorb CO₂?

b. The following results were obtained during the analysis of the reaction
N₂O_4[g] ⇌ 2NO_2[g] at 25°C
[N₂O₄] = 6.20M, [NO₂] = 13.60M
Calculate the equilibrium constant [K_c] for the reaction.

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