1. Experiment Snapshot
| Feature | Details |
|---|
| Apparatus | Boiling tube/conical flask, delivery tube, gas jar, water trough, bung, clamp stand. |
| Chemicals/Reagents | Hydrogen peroxide and manganese dioxide catalyst, or potassium chlorate with catalyst depending on method. |
| Main observation | Bubbles of oxygen gas are produced; oxygen relights a glowing splint. |
| Main measurement | Collection of oxygen gas and positive gas test. |
2. Aim
To prepare oxygen gas in the laboratory and test it using a glowing splint.
3. Quick Theory
Hydrogen peroxide decomposes to form water and oxygen. Manganese dioxide speeds up the reaction as a catalyst.
2H₂O₂ → 2H₂O + O₂
Examiner Tip: Oxygen relights a glowing splint; it does not give a squeaky pop.
4. Apparatus, Chemicals and Safety
| Category | Details |
|---|
| Apparatus | Boiling tube/conical flask, delivery tube, gas jar, water trough, bung, clamp stand. |
| Chemicals | Hydrogen peroxide and manganese dioxide catalyst, or potassium chlorate with catalyst depending on method. |
Safety: Wear goggles. Hydrogen peroxide can irritate skin/eyes. Oxygen supports combustion. Keep flames controlled.
5. Labelled Experiment Diagram
Preparation and Testing of Oxygen — Premium Practical Setup
6. Procedure
- Place hydrogen peroxide in a conical flask.
- Add a small amount of manganese dioxide catalyst.
- Quickly fit bung and delivery tube.
- Collect oxygen over water in an inverted gas jar.
- Allow first bubbles to escape if air is present.
- Collect a jar of oxygen.
- Insert a glowing splint into the gas jar.
- Observe the splint relighting.
Examiner Tip: The splint must be glowing, not burning with a flame.
7. Observations and Results
| Stage / Test | Observation | Conclusion |
|---|
| Gas production | Bubbles form | Oxygen produced |
| Glowing splint | Relights | Oxygen present |
| Catalyst | MnO₂ remains | Catalyst not used up |
Conclusion: Oxygen can be prepared by decomposition of hydrogen peroxide and identified because it relights a glowing splint.
8. Calculations / Key Chemical Reasoning
The balanced equation shows one mole of oxygen forms from two moles of hydrogen peroxide.
2H₂O₂ → 2H₂O + O₂
Worked Example:
If gas relights a glowing splint, the sample contains oxygen.
9. Sources of Error and Improvements
| Source of Error | Effect | Improvement |
|---|
| Gas leaks | Less oxygen collected | Check airtight setup |
| First gas contains air | Impure sample | Discard first bubbles |
| Splint too hot/flaming | Test unclear | Use glowing splint |
| Too much catalyst | Reaction too vigorous | Use small amount |
| Delivery tube removed late | Suck-back risk | Remove before stopping if heated method used |
10. Student Common Mistakes
- Using lighted splint test.
- Calling the gas hydrogen.
- Saying catalyst is used up.
- Forgetting oxygen supports combustion.
- Not collecting gas over water correctly.
11. Examiner Tips
Tip: Oxygen relights glowing splint.
Tip: MnO₂ is a catalyst.
Tip: Collect over water if gas is not too soluble.
Tip: Keep flames controlled.
12. Examiner Traps
Trap: Glowing splint, not lighted splint.
Trap: Catalyst speeds reaction but is not consumed.
Trap: Oxygen supports combustion but is not itself a fuel.
13. 🎮 Interactive Simulator
Oxygen Gas Test
Choose conditions and test gas.
Observation Window
Gas jar
Choose a condition and run the simulation.
Lab Score: 0/0
14. Past Paper Style Questions
- State the aim of this experiment. [2 marks]
- Name the main apparatus or reagent used. [2 marks]
- Describe the key observation expected. [2 marks]
- Give one safety precaution. [1 mark]
- Give one source of error and one improvement. [2 marks]
- Explain the chemistry behind the result. [3 marks]
15. Mark Scheme Answers
Q1. To prepare and test oxygen gas [2].
Q2. Flask, H₂O₂, MnO₂, delivery tube, gas jar [2].
Q3. Bubbles form and glowing splint relights [2].
Q4. Wear goggles and keep flames controlled [1].
Q5. Gas leak; check airtight apparatus [2].
Q6. Hydrogen peroxide decomposes to water and oxygen, catalysed by MnO₂ [3].
16. Quick Revision Card
| Key Point | Memory Hook |
|---|
| Gas | Oxygen |
| Test | glowing splint relights |
| Catalyst | MnO₂ |
| Equation | 2H₂O₂ → 2H₂O + O₂ |
| Safety | supports combustion |
17. Mastery Checklist
- I can prepare oxygen.
- I can state the test.
- I can write equation.
- I can explain catalyst role.
- I can identify errors.