Question 1: Define dynamic equilibrium in the context of chemical reactions.

Answer: Dynamic equilibrium occurs when the forward and reverse reactions in a chemical system occur at the same rate, resulting in constant concentrations of reactants and products.

Question 2: Describe how the concentration of reactants and products changes once equilibrium is established.

Answer: The concentrations of reactants and products remain constant over time, although both reactions continue to occur simultaneously.

Question 3: Explain the effect of changing concentration, temperature, or pressure on a system at equilibrium.

Answer: Changing these factors shifts the position of equilibrium according to Le Châtelier’s principle, favoring the reaction that counteracts the change.

Question 1: Given the reaction: N₂(g) + 3H₂(g) ⇌ 2NH₃(g). If at equilibrium, the concentration of NH₃ is 0.5 mol/L, and the concentrations of N₂ and H₂ are 0.2 mol/L and 0.6 mol/L respectively, calculate the equilibrium constant (Kₑq).

Answer: Kₑq = (0.5)² / (0.2)(0.6)³ = 0.25 / (0.2)(0.216) = 0.25 / 0.0432 ≈ 5.79

Question 2: If the initial concentration of reactants is 1.0 mol/L N₂ and 3.0 mol/L H₂, and the system reaches equilibrium with 0.4 mol/L of NH₃ formed, what is the concentration of N₂ remaining at equilibrium?

Answer: Change in N₂ = -x = -0.4 mol/L; Remaining N₂ = 1.0 - 0.4 = 0.6 mol/L

Question 1: Describe a simple experiment to demonstrate dynamic equilibrium involving a reversible reaction in a laboratory setting.

Answer: A common experiment involves the reaction between iodine and starch in a solution that reaches equilibrium, demonstrating color change as the reaction proceeds both forward and backward.

Question 2: Identify three variables that can be changed in an experiment to observe shifts in equilibrium, and specify the safety precautions to consider.

Answer: Variables include concentration, temperature, and pressure. Safety precautions include wearing goggles, gloves, and working in a well-ventilated area when handling chemicals.

Question 1: In a reaction at equilibrium, increasing the temperature causes the concentration of products to decrease. What does this imply about the reaction’s enthalpy change?

Answer: It suggests that the reaction is exothermic, and increasing temperature shifts the equilibrium toward the reactants to absorb excess heat.

Question 2: A manufacturing process uses the Haber process to synthesize ammonia. Explain how understanding dynamic equilibrium can improve yield and process efficiency.

Answer: By manipulating temperature, pressure, and reactant concentrations to favor the forward reaction, operators can optimize ammonia production. Understanding equilibrium allows for adjustments that maximize yield while minimizing energy consumption and waste.

Question 1: Explain the concept of dynamic equilibrium using the Haber process as an example. Include how Le Châtelier’s principle can be applied to optimize ammonia production. (6 marks)

Answer: Dynamic equilibrium occurs when the forward and reverse reactions in the Haber process occur at the same rate, resulting in a constant concentration of ammonia. By increasing pressure, the equilibrium shifts toward the formation of ammonia, since the reaction produces fewer moles of gas. Lowering temperature favors ammonia formation but must be balanced against reaction rate. Adjusting these conditions based on Le Châtelier’s principle enables better yield and efficiency.