Making Chlorine Gas

Materials: ★★☆ Available in most school laboratories or specialist stores
Difficulty: ★★☆ Can be done by science teachers
Safety: ★★★ Only to be attempted with adequate safety procedures and trained staff

Categories: Elements and Periodic Table, Gases

Alternative titles: Preparation of Chlorine from Permanganate

Summary

Chlorine gas, a pale greenish-yellow substance, can be produced by reacting potassium permanganate with concentrated hydrochloric acid.

Procedure

Place a small quantity of potassium permanganate crystals into a flask.
Add concentrated hydrochloric acid drop by drop onto the crystals.
Collect the chlorine gas by upward displacement of air (chlorine is denser than air) inside a fume hood.
Observe the characteristic pale green-yellow color of chlorine gas.

Links

Make Chlorine Gas (fixed) - NurdRage:

Preparation of chlorine - Hegelrast:

📄 How to Make Chlorine Gas - Science Notes: https://sciencenotes.org/make-chlorine-gas/

Variations

Compare this method with chlorine production from the electrolysis of brine.
Test chlorine’s bleaching properties using damp litmus paper (it is bleached and turns white).

Safety Precautions

Chlorine gas is toxic — conduct only in a fume hood.
Wear chemical splash goggles, gloves, and a lab coat.
Concentrated hydrochloric acid is highly corrosive — handle with extreme care.
Do not inhale chlorine; exposure may cause severe respiratory harm.
Dispose of residues safely following institutional guidelines.

Questions to Consider

What is the balanced chemical equation for this reaction? (6HCl + 2KMnO₄ → 3Cl₂ + 2MnO₂ + 4H₂O + 2K⁺)
Why is chlorine collected by upward displacement of air? (It is denser than air.)
What are some uses of chlorine gas? (Water disinfection, bleach production, PVC plastics.)
Why is chlorine considered dangerous to work with? (It is toxic, corrosive, and can cause lung damage.)
How does this reaction demonstrate both oxidation and reduction? (Mn is reduced from +7 to +4, Cl⁻ is oxidized to Cl₂.)