Tests for Oxygen

Purpose of Oxygen Test

The test for oxygen gas is used to confirm its presence in a sample. It is important to distinguish oxygen from other gases because oxygen supports combustion and is essential for respiration. This test helps identify oxygen quickly and reliably in a laboratory or classroom setting.

Oxygen is colourless and odourless, so visual or smell tests are ineffective. Instead, its chemical property of supporting combustion is used to detect it.

Glowing Splint Test

The most common and straightforward test for oxygen is the glowing splint test. This involves the following steps:

• Light a wooden splint and then blow it out so it is glowing but not flaming.
• Insert the glowing splint carefully into the gas sample.
• If oxygen is present, the glowing splint will relight with a bright flame.

This test works because oxygen supports combustion. When the glowing splint is placed in an oxygen-rich environment, the increased oxygen concentration allows the splint to burst back into flame.

The glowing splint test is simple, quick, and effective for identifying oxygen gas without the need for chemical reagents or complex equipment.

Observations and Results

When performing the glowing splint test:

• If oxygen is present: The glowing splint reignites and produces a bright flame.
• If oxygen is absent: The splint remains glowing but does not relight.

This observation confirms that oxygen supports combustion, which is why the splint bursts into flame only when oxygen is in the gas sample.

For instance, if you collect gas from a reaction that produces oxygen, such as the decomposition of hydrogen peroxide (2H₂O₂ → 2H₂O + O₂), and test it with a glowing splint, the splint will relight, confirming oxygen is present.