Rates of Reaction
Marble chips + acidCaCO₃ + 2HCl → CaCl₂ + H₂O + CO₂Every trial can make the same 100 cm³ of gas—only the speed changes.
Model rate index1.0×
Contact index1.0×
Temperature effect1.0×
Time to collect half17.3 s
Comparative classroom model—not an experimentally fitted rate law. Every trial uses the same limiting amount of CaCO₃ and enough HCl to remain in excess, so the predicted final CO₂ volume stays at 100 cm³. Curve shape and times illustrate the expected trends; they are not measured results.
Gas volume curve0.0 cm³
- Make the reaction at least twice as fast (rate ≥ 2×)
- Use powdered marble to maximise exposed surface area
- Get the reaction to 4× the baseline rate
- Slow it to half the baseline rate
- Combine factors to reach 16× the baseline rate