Measuring gas volume over time for reaction rate

Steps:

• Identify apparatus that collects and measures CO2 gas produced from CaCO3 + 2HCl → CaCl2 + H2O + CO2.
• Diagram 1 uses a gas syringe attached to flask for direct volume readings.
• Diagram 2 employs delivery tube to inverted cylinder in water trough for gas displacement measurement.
• Diagram 3 lacks proper gas collection, like open setup without volume gauge.

Why B is correct:

• Diagrams 1 and 2 enable accurate, real-time CO2 volume tracking, essential for plotting rate curves per rate law definitions.

Why the others are wrong:

• A omits suitable diagram 2, which validly measures displaced water volume.
• C includes unsuitable diagram 3, which prevents quantitative gas volume data.
• D adds invalid diagram 3, risking inaccurate or no rate measurement.

Final answer: B