Test for oxygen using glowing splint

Chemical analysis • Identification of common gases

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How is the gas sample held during the test?

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The gas sample is collected in a dry test tube or gas jar held upright for insertion of the splint.

Key concepts

What you'll likely be quizzed about

Definition and principle

Oxygen is a colourless, odourless gas that supports combustion. The principle of the test relies on increased availability of oxygen causing the rate of combustion to rise. A glowing ember receives more oxygen and undergoes faster oxidation, producing visible flame.

Step-by-step procedure

A wooden splint receives a flame and is then blown out to leave a glowing tip. The gas sample is collected in a dry test tube or gas jar and held upright. The glowing splint is inserted carefully into the gas container. Relighting of the splint into a flame indicates the presence of oxygen because the higher concentration of oxygen restores active combustion.

Expected observation and interpretation

Relighting of the glowing splint into a flame signals oxygen presence. No change or continued dull glow suggests absence of sufficient oxygen or presence of inert or non-supporting gases. A rapid flare or bright flame indicates a higher partial pressure of oxygen around the splint.

Limiting factors and false results

Contaminants such as vapours or other oxidising gases can cause misleading flares. Low oxygen concentration can fail to relight the splint even when some oxygen is present. Wet or impure glassware and an insufficiently glowing splint reduce reliability. Controlled collection and testing reduce false positives and negatives.

Safety and practical notes

Open flame and hot splints present burn and fire risks. Small gas volumes in closed containers reduce exposure but require careful handling. Experiments take place away from flammable materials. Proper disposal of burning splints and supervision reduces risk.

Key notes

Important points to keep in mind

A glowing splint relighting into a flame indicates oxygen presence.

The test provides a qualitative result, not a concentration measurement.

Use a well-glowing ember, not an active flame, to insert into the gas sample.

Avoid contaminated or wet apparatus to reduce false results.

Keep the area clear of flammable materials and wear eye protection.

Very small gas volumes can give false negatives due to insufficient oxygen.

Oxidising contaminants can cause false positives; use controls when possible.

Extinguish and dispose of splints safely after testing.