Oxygen is one of the most essential substances found on earth--without it, many chemical reactions would not take place, and people would not be able to breathe. However, oxygen has no color or smell and doesn't make litmus paper react the way other gases do. Testing for oxygen thus involves a different strategy than testing for other gases.

Gas Capture

In order to test for the presence of oxygen, you'll first need to capture some of the gas. There are two ways to do this: Connect a tube to a beaker in which a chemical reaction producing gas is taking place. Put the other end into a tub of water. Then hold a test tube upside down over the end of the tube that is submerged in the water. The gas will travel from the beaker, through the tube, into the water, and be captured as it moves upward out of the water. Connect a tube to a beaker in which a chemical reaction producing gas is taking place. Connect the other end of the tube to a gas syringe. The gas produced in the reaction will travel from the beaker through the tube and be captured in the syringe as the syringe plunger is pushed out by the gas.

Matches

If you have captured your gas using the water method, next take a glowing splint (e.g., a match that isn't quite out) and put it in the test tube. If you see a resurgence of flame, the presence of oxygen is confirmed, since oxygen is needed for a substance to burn. If you have captured your gas using the syringe method, you may need to put your captured gas into a test tube first, but you also can hold a splint just outside the end of the syringe as you very slowly push in the syringe plunger.

Other Tests

Other tests may be done to test for the presence of oxygen, such as oxygen blood level tests. These tests usually rely on more technological means of measuring oxygen, so if you want to test for oxygen extremely precisely, you'll need to call a laboratory. Although it's possible to use very precise math to figure out the amount of oxygen you've given off and captured, it's much easier to use the basic method of testing for oxygen just to confirm the presence of the gas rather than to measure the exact amount you have.

Safety

If you are testing for oxygen yourself, always wear protective gear like goggles and gloves, especially if you truly don't know what other gases might be involved in the chemical reactions that are occurring. Use long-stemmed matches to prevent burns.

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Test for Oxygen