Fast Fact:
Methanol, which is used to fuel Indy cars, burns with a clear flame, making it a potentially invisible hazard in daylight. However, methanol is less explosive than gasoline and is readily dispersed and extinguished with water.
Objective:
To demonstrate how fires are put out at the racetrack.
In the Film:
With the large amounts of methanol fuel being handled in the pits and travelling on board fast-moving cars, fire is a major hazard at the track. Numerous regulations exist to prevent fires and to control them when they break out. Each car has an automatic fire extinguisher system, each pit contains at least one fire extinguisher, the crew wears fireproof suits during pit stops, and the drivers wear suits made of fireproof materials.
Materials:
Baking soda (sodium bicarbonate), vinegar (acetic acid), a small jar (between 250mL and 500mL), a large jar (between 750mL and 1L), plasticine or modelling clay, a small birthday candle, matches or a lighter.
To Do:
The students must follow all safety protocols. Working in pairs, have them attach the candle to the bottom of the small jar with the plasticine. Pour about 200mL of water into the large jar with 125mL of vinegar. Then add about 15mL of baking soda. Stand back and watch the chemical reaction. Have the students light the candle in the small jar. They should then slowly tip the large jar over the opening of the small jar without pouring out any of the liquid. What happens? Ask the students to observe the substance formed in the jar and name two physical properties (i.e., color) and one chemical property (i.e., the smell that came out of the jar). Their answers should be based on the results of the experiment.
Whats Going On?
When baking soda is mixed with an acid such as vinegar, a chemical reaction occurs that produces C02 (carbon dioxide). Since C02 (a gas) is heavier than air, it pushes the air out the top of the jar in order to occupy the bottom. When you tip the bottle, the heavier C02 goes into the small jar, filling the bottom and replacing the oxygenated air. The C02 deprives the flame of oxygen, snuffing it out. Some of the properties of C02 are that it is a colorless, odorless, tasteless gas that has a greater density than air and does not sustain combustion.
Taking It Further:
1. Ask the students to research various fire extinguisher designs.
2. Have them explain the strategies behind each of the extinguishers they researched. They should base their answers on the three requirements of combustion.