How breathing, burning, rusting changes air

Breathing, burning and rusting, what do these have in common? People and animals need air - or more precisely, the oxygen from the air - to breathe. How is this process comparable with the burning, for example, of a candle or with the rusting of iron? To answer this question, you should perform the following experiments.

1. Fill an ampoule to a height of approximately 2 cm with lime water.

2. Blow air with the straw slowly and carefully into the lime water.

(more see below)

3. Light the lighter and put the infusion bottle over it.

4. Turn the infusion bottle over, put into it a few drops of lime water, stopper it and shake it.

5. Put into another ampoule a few drops of water.

6. Now push two roughly equal pieces of steel wool to the bottom of this and a dry ampoule. Label the two ampoules with W (water) and with K (control).

7. Cutting the two pipette tips from the thick end and push them from the top through the stoppers of the ampoules.

8. Close the two prepared ampoules with wet and with dry steel wool with these stoppers.

9. Fill two more ampoules until just below the shoulder with coloured water and stand them in the stoppers of infusion bottles.

10. Place the ampoules with the steel wool upside down in the ampoules with the coloured water, so that the pipette tips are immersed in water.

11. Keep the ampoules for several hours in a safe place in the stands.

First published: 1999 last modification: 24.07.2014