Preparing and testing gases

A/L Chemistry · G.C.E. Advanced Level · Grades 12–13

Aim

To prepare some gases and identify them with chemical tests.

Apparatus

• Gas generator and delivery tube
• Reagents (H₂O₂/MnO₂, CaCO₃/HCl, Zn/HCl…)
• Splints, limewater, litmus

Method

1. Mix the reagents and collect the gas.
2. Test with glowing and burning splints.
3. Test with limewater, litmus and a rod dipped in conc. HCl.
4. Identify the unknown gas.

Conclusion

O₂ relights a glowing splint; CO₂ turns limewater milky; H₂ burns with a “pop”; NH₃ turns red litmus blue and gives white fumes with HCl; Cl₂ bleaches litmus.