Apparatus for measuring temperature and acid volume in gas evolution reaction

Steps:

• Identify variables: temperature affects reaction rate via kinetic energy; acid amount via concentration or volume.
• Recall experiment setup: gas syringe measures rate by volume over time; vary temperature with thermometer and acid volume with measuring cylinder.
• Eliminate irrelevant tools: balance for mass, condenser for distillation—not needed here.
• Select pair matching both variables directly.

Why D is correct:

• Thermometer measures temperature changes (per collision theory, higher temperature increases particle collisions); measuring cylinder quantifies acid volume for concentration control.

Why the others are wrong:

• A: Balance measures mass loss, not acid volume; misses precise volume variation.
• B: No temperature measurement; balance irrelevant for liquid volume.
• C: Condenser unnecessary for open gas collection; cylinder too vague for specifics.

Final answer: D