Simulation of Rate of reaction measurement using syringe and inverted cylinder
Rate of Reaction Simulation — Description & Class Activity
What the Simulation Shows
A 3D interactive experiment measuring the volume of CO₂ gas produced when marble chips (calcium carbonate) react with hydrochloric acid:
CaCO₃(s) + 2HCl(aq) → CaCl₂(aq) + H₂O(l) + CO₂(g)
Students can switch between two real laboratory methods for collecting the gas:
Tab 1 — Gas Syringe: CO₂ travels from the sealed conical flask through a delivery tube into a horizontal syringe. The plunger is pushed outward as gas enters, and students read the volume directly off the barrel scale.
Tab 2 — Inverted Measuring Cylinder: CO₂ bubbles up through a delivery tube into a water-filled cylinder held upside-down in a trough. Gas collects at the top and displaces water downward, and students read the volume from the falling water level.
Both methods share the same flask setup — marble chips sitting in hydrochloric acid sealed with a red rubber bung — and both show CO₂ bubbles forming at the marble surfaces, travelling through the tube, and collecting in the apparatus. A live V vs t graph plots in the corner throughout.
The concentration slider (0.5–2.5 mol/dm³) changes two things simultaneously and correctly: the rate of the reaction (steeper curve at higher concentration) and the total volume collected (more CO₂ at higher concentration, because HCl is the limiting reactant with marble chips in excess). The acid colour shifts from pale blue toward yellow-green as concentration increases, giving a visual cue to solution strength. Marble chips visibly shrink and disappear as the reaction completes.
Suggested Class Activity
“How does concentration affect the rate and total volume of CO₂ produced?” Suitable for: GCSE Chemistry, Year 10–11 | Time: 30–40 minutes
Learning objectives
- Describe how concentration affects the rate of a reaction in terms of collision frequency
- Explain why the limiting reactant determines the total volume of gas produced
- Extract rate from a V vs t graph by reading the initial gradient
Starter (5 min)
Show the simulation paused at the default setting (1.0 mol/dm³). Ask:
“The plunger hasn’t moved yet. Predict — if I double the concentration, what do you think will happen to (a) how fast the plunger moves, and (b) where it stops?”
Take two or three answers. Don’t confirm either — tell students the simulation will help them decide.
Main activity (20 min)
Students work individually or in pairs through three runs, each time pressing Reset before changing the slider. They record results in this table:
| [HCl] (mol/dm³) | Final volume (cm³) | Time to reach final volume (s) | Describe the graph shape |
|---|---|---|---|
| 0.5 | |||
| 1.0 | |||
| 2.0 |
After collecting data, students answer:
- What happens to the final volume as concentration increases? Why?
- What happens to the time taken as concentration increases? Why?
- Look at the first few seconds of each graph. Which run has the steepest gradient? What does gradient represent here?
- Which reactant is the limiting reactant in this experiment? How does the simulation show this?
- Sketch what you think the V vs t graph would look like if the marble chips ran out before all the HCl was used up. How would that change your answers?
Discussion (10 min)
Draw out three key ideas:
- Rate ↑ with concentration because more HCl particles are in the same volume → more frequent collisions with the marble surface → more successful collisions per second
- Total volume ↑ with concentration because moles of CO₂ produced = ½ × moles of HCl. More concentrated acid = more moles of HCl = more CO₂
- The graph flattening shows the reaction stopping — not because it slowed to zero but because one reactant ran out
Ask: “If we used less marble chips and kept the acid the same, which reactant would now be limiting? Would your results table look different?” (Yes — final volume would now be fixed regardless of [HCl], and rate would still vary.)
Extension question
A student claims: “If I use 2.0 mol/dm³ HCl instead of 1.0 mol/dm³, my reaction will produce gas twice as fast AND collect twice as much gas.” Are they correct about both claims? Use the simulation and your results table to justify your answer.
(Answer: correct on both counts in this setup, because HCl is limiting — but this only holds while marble chips remain in excess.)
SEND adaptations built into the simulation
- ♿ button opens the accessibility panel: text size (Normal/Large/X-Large), reading ruler, Irlen overlays, dyslexia spacing, reduce motion and extra slow toggles
- Labels button hides/shows all on-screen annotations to reduce visual load
- Extra Slow mode lets lower-attaining students track the plunger movement step by step