Refraction Education : NRMA Car Safety (Years 9-10)
60 THE ROAD SAFETY TOTAL LEARNING RESOURCE • YEARS 9–10 ELABORATE ACTIVITY 5 COMBUSTION OF METHANE (TEACHER DEMO) Background: This is a fun demonstration, but students must not crowd around the teacher during the demonstration. They should remain a safe distance away. Materials: • One large clean coffee tin (the larger commercial size rather than the size that is for general domestic use) • Rubber or plastic hose from a Bunsen burner • Tripod • Gas outlet • Matches Before the demonstration: 1. Wash and clean a large coffee tin with a lid that seals tightly. 2. Make a small hole in the lid of the tin. 3. Make a second larger hole at the bottom large enough for the Bunsen burner hose to fit into. During the demonstration:: 1. Ensure the lid is secured tightly on the tin. 2. Sit the tin on a tripod. 3. Attach one end the Bunsen burner hose to the gas supply. Attach the other end of the hose to the second larger hole at the bottom of the tin. Turn on the gas for approximately one minute so that the entire tin is full of methane from the gas tap and the air is pushed out. 4. Turn off the gas supply and remove the hose from the bottom of the tin. 5. Place a lit match near the small hole in the lid of the tin so that a flame is produced from the gas escaping through the top. 6. The flame will need to burn for a few minutes so that some oxygen can enter the hole at the bottom as the methane is burned. The flame will sink low into the can. While you are observing the flame, predict what is going to happen during the remainder of the experiment. 7. After a few minutes, once the ratio of oxygen to methane is optimum, the methane will combust and make a loud ‘pop’ sound as the lid flies up. Students do not usually expect this as they think the experiment has not worked when the flame dies down. 8. When the can has cooled examine it for the presence of water, which should be visible inside the can as tiny droplets. 9. Repeat Steps 1–8 if necessary! The same tin may be used again, as long as the lid of the tin still fits tightly.
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