simple way of testing the air

Simple way of testing the air is to duplicate John Mayow’s experiment showing that burning consumes a substance in air.

aksiografi.com—The atmosphere, that thick blanket of gas enveloping the earth, provides gases necessary for the life of plants and animals. It also serves as a shield of protection from the sun’s intense heat.

In previous experiments we have done to forecast the weather by obsreving chemical processes. The air carries the water droplets and then forms a cloud. In the rainy season, the air experience humidty as we have tesed it hygroscopically using a simple hygrometer. Both the previous tests showed that air is both a life support and protector for creatures’ life.

In this project, you will determine some of the chemical and physical properties of air. You will also look at the history of the discovery of the composition of a substance in air.

Learning Objective

Learning objective of simple way of testing the air is to duplicate John Mayow’s (1641–1679) experiment showing that burning consumes a substance in air.

picture of John Mayow

Materials

modeling clay

candle (about half as tall as the jar used)

cereal bowl

water

red food coloring

match

1-pint (500-ml) glass jar

Procedure

1. Use the clay to secure the candle to the bottom of the bowl so that the candle stands upright.

2. Fill the bowl three-fourths full with water.

3. Add drops of food coloring to make the water in the bowl a deep red.

4. Light the candle with the match. CAUTION: Be careful not to get your clothing or hair close to the flame.

5. Turn the jar upside down, quickly lower it over the burning candle, and stand it on the bottom of the bowl (see Figure).

picture of testing the air

6. When the flame goes out, observe the water level inside the jar.

Results of Testing the Air

The results of a simple way of testing the air is a bubble of gas escapes when the jar is placed into the water. As the candle burns, the water rises up into the jar.

Why?

John Mayow correctly concluded that air contains a substance needed for burning. His term for this substance was ”nitro-aerial spirit.” His experiment, which you duplicated, was used to show that burning removed the nitro-aerial spirit from the air, leaving an empty space that was filled by the water.

Mayow believed that the amount of water that rose up into the jar was equal to the amount of nitroaerial spirit that left. Some people still use Mayow’s experiment to demonstrate that water takes the place of the oxygen that is removed as a result of the burning of the candle.

If Mayow had known that heated gases expand, do you think his conclusion would have been the same? Yes, oxygen is being removed from the air, but the burning candle is producing carbon dioxide gas and water vapor. Do these gases not fill some, if not all, of the space left by the removal of elemental oxygen? These questions will be explored in the next section. Information gathered from further experimentation and research will provide you with an explanation of this experiment.

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