Consider the reaction represented by the following equation: CuO (s) + H 2 SO 4(aq) → CuSO 4(aq) + H 2 O (l)…

Step 1: Analyze the question We are asked which factor will not affect the rate of the reaction CuO(s) + H₂SO₄(aq) → CuSO₄(aq) + H₂O(l).

Step 2: Concept: factors affecting reaction rate Reaction rate depends on:

• Surface area / particle size of solid reactants: smaller particles give a larger surface area, so there are more collisions and a faster rate.
• Concentration of reactants in solution: a higher concentration gives more frequent collisions.
• Temperature: a higher temperature gives particles more kinetic energy, so more collisions have enough energy to react.
• Catalyst
• Pressure: this matters only when gases are involved, because changing pressure changes the concentration of a gas.

Step 3: Apply to each option

• A. Particle size of CuO(s): CuO is a solid, so a finer powder reacts faster. This affects the rate.
• B. Concentration of H₂SO₄(aq): This affects the rate.
• C. Temperature: This affects the rate, and warming is often used to speed up this reaction.
• D. Pressure of the reaction system: The reactants are a solid and an aqueous solution, and no gas is involved. Solids and liquids are practically incompressible, so pressure has no significant effect on the rate.

Answer: D

Tip: When you see "pressure" in a rate question, check for gases first. If the reactants and products are only solids and liquids (s, l, aq), pressure will not affect the rate. This also applies to equilibrium questions.