What are the common tests for detecting oxygen gas?

The common tests for detecting oxygen gas are the glowing splint test and the oxidation reaction test.

The glowing splint test is the most common and straightforward method for detecting oxygen gas. In this test, a wooden splint is lit and then blown out to produce a glowing ember at the end. This glowing splint is then inserted into a test tube containing the gas. If the splint re-ignites, it indicates the presence of oxygen, as oxygen supports combustion.

Another test for oxygen involves observing an oxidation reaction. Oxygen gas can cause substances to oxidise, which means they gain oxygen. For example, if you pass oxygen over hot copper, the copper will turn black as it forms copper(II) oxide. This is a clear indication of the presence of oxygen.

It's important to remember that while these tests are generally reliable, they are not foolproof. Other gases can also cause a glowing splint to re-ignite or substances to oxidise. Therefore, these tests should be used as initial indicators, and further tests may be needed to confirm the presence of oxygen.

Safety is paramount when conducting these tests. Always ensure you are working in a well-ventilated area, away from flammable materials. Never directly inhale the gas being tested, and always use heat-resistant equipment when dealing with hot substances.