### Solution
Part A. What is dynamic equilibrium? (1 mark)
Dynamic equilibrium is a state in a reversible reaction where the rate of the forward reaction equals the rate of the reverse reaction. This balance means that the concentrations of reactants and products remain constant over time, even though both reactions are still occurring.
Part B. Effects of increasing temperature and pressure (3 marks)
Let's analyze the given reaction and determine the effects:
[tex]\[
2 \text{SO}_2 (g) + \text{O}_2 (g) \rightleftharpoons 2 \text{SO}_3 (g) \quad \Delta H = -196 \, \text{kJ/mol}
\][/tex]
- Effect of increasing temperature:
1. Effect on the rate of reaction (i): Increasing the temperature increases the kinetic energy of the molecules involved in the reaction. Higher kinetic energy results in more frequent and more energetic collisions among molecules, which increases the rate of both the forward and reverse reactions.
2. Effect on the position of equilibrium (ii): Since the reaction is exothermic (ΔH = -196 kJ/mol), increasing the temperature will shift the position of equilibrium to the left, favoring the endothermic reverse reaction. This is a consequence of Le Chatelier's Principle, which states that the system will adjust to counteract the change—in this case, by absorbing the extra heat and producing more reactants.
- Effect of increasing pressure:
1. Effect on the rate of reaction: The "stay the same" answer indicates that increasing pressure does not directly affect the rate of reaction because the pressure increase uniformly affects all gases present, thus canceling out any direct changes in reaction rate.
2. Effect on the position of equilibrium (iii): Increasing the pressure will shift the equilibrium position to the right, towards the side with fewer moles of gas. In this reaction, the reactants side has three moles of gas (2 moles of SO₂ + 1 mole of O₂) while the products side has two moles of gas (2 moles of SO₃). Therefore, an increase in pressure favors the formation of SO₃, shifting the equilibrium to the right.
Completed Table:
[tex]\[
\begin{array}{|l|l|l|}
\hline
& \text{Effect on the rate of reaction} & \text{Effect on the position of equilibrium} \\
\hline
\text{Increasing the temperature} & (i) \text{Increases the rate of reaction} & (ii) \text{Shifts equilibrium to the left} \\
\hline
\text{Increasing the pressure} & \text{Stay the same} & (iii) \text{Shifts equilibrium to the right} \\
\hline
\end{array}
\][/tex]
