Final answer:
To confirm oxygen gas in a jar, the glowing splint test can be conducted by introducing a glowing splint into the jar; the presence of oxygen is confirmed if the splint reignites. The collection of oxygen can also be done by using the downward displacement of water technique in reactions that release oxygen, such as the one between hydrogen peroxide and manganese dioxide.
Step-by-step explanation:
To test if oxygen gas is present in a jar, one commonly used method is the glowing splint test. In this test, you first light a wooden splint and then extinguish the flame, leaving the splint glowing. When you introduce the glowing splint into the jar containing the gas, the presence of oxygen gas is confirmed if the splint bursts back into flame. The increase in the combustion reaction rate is due to the high concentration of oxygen as compared to the air, which contains about 20% oxygen. This is a reliable chemical test because oxygen is the only gas that supports combustion to this extent.
Another setup to test for oxygen generation involves a reaction between hydrogen peroxide and manganese dioxide. Upon adding manganese dioxide to hydrogen peroxide, oxygen gas is released and collected by the downward displacement of water technique. This allows the collection of oxygen because it is less dense than water and does not readily dissolve in it. Confirming the presence of oxygen can then be accomplished using the glowing splint test mentioned earlier, by introducing the splint into the gas collected in the test tube.