Question

The exhaled air consists of a higher percentage of carbon dioxide. Justify with the experiment.

Answer 1

Breathing process involves inhalation and exhalation. Composition of carbondioxide in the inhaled air and the exhaled air vaires. Inhaled air consists of less percentage of carbon dioxide (0.04%) compared to exhaled air where the carbon dioxide concentration is more which is 4.4%. This can be proved with the help of a lime water experiment.

Procedure:

• Two jars are taken. One jar with normal water another jar with lime water is taken.
• Both the jars are closed with a holed stopper. A connecting tube which is elongated towards one end is inserted into the jar as shown in the image.
• An L shaped tube is inserted into the jar through another hole for the exhaled air to go out as shown in the image.
• Air is blown for a few minutes through the pipe.

Observation:

• Lime water turns milky after the air is blown.
• There is no colour change in the normal water.

Conclusion:

• Air which we blow (exhaled air) contains more carbon dioxide. Hence, it reacts with the lime water to form calcium carbonate. This turns the lime water milky.