Inhaled vs Exhaled air experiment: Method 1

Aim: Comparing the inhaled and exhaled air.

Materials: large transparent container (e.g. bell jar), candle, tin lid, water, large basin, rubber tubing, ruler.

Method

1. Place the large transparent container over a lighted candle floating in a basin of water as shown above.
2. Measure how far the water rises up the container after the candle has been extinguished/has gone out.
3. Repeat this with a sample of exhaled air. Fill the container by blowing in exhaled air after holding your breath for about 30 seconds. This will fill the container with exhaled air.
4. Place a candle inside the container and measure the water displacement again.

Results and explanation

• The water displacement in the first instance i.e. when natural air is used is greater as the air containers more oxygen which is used up by the candle.
• Oxygen combines with carbon to form carbon dioxide.
• The candle eventually goes out as oxygen runs out and the container is filled with carbon dioxide.
• The candle in the first instance burns for a longer time as natural air contains more oxygen.
• There is less displacement in the second instance as the exhaled air contains less oxygen.

Conclusion

• Inhaled air contains more oxygen and less carbon dioxide when compared to exhaled air which contains less oxygen and more carbon dioxide.

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