Science requires a dedication to the principles of experimentation. In many classrooms across the country, these experiments–even some that are hands on–tend to bore the student-scientists conducting them. Not this one.
It is a fairly safe concept that erupts in dramatic effect. And fire has a way of capturing the imagination. Maybe the students were concerned for their safety, or that of their teacher–but there’s no doubt that they were engaged.
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Don’t attempt this at home. Though the experiment is safe, and easily replicated, there are numerous ways that it can go wrong. The result, it should seem obvious, involves flaming liquids.
The concept is simple enough. Find a flammable liquid–most prefer alcohol–pour out small amount on a flame-resistant surface and light light it up. Alcohol will evaporate quickly, so it is relatively safe.
The next step is where the magic happens. Pour a small amount into a container–something with a narrow opening, like a jug or bottle. Carefully ignite the residual liquid at the mouth.
The flame will cascade into the container, which is fun to watch. The noise of the ignition is captivating, too. And then the flame will funnel out the open mouth. The bottleneck focuses the flame as it is exposed to oxygen, and that tends to roar like a small jet engine.
The flames leaping from the bottle and the noise has this class on the edge of their seats. The expanding gasses inside the bottle won’t explode the container. They seek the path of least resistance, and that is through the open end of the bottle.
The teacher then does something that’s really a bonus. Just as the flames die, he presses his hand to the top of the bottle. This cuts off the air supply to the flame, and it is extinguished. But there’s a more dramatic effect that happens and it makes a great conclusion to the lesson.