You can Investigate the Proportion of Oxygen in the Atmosphere Using Iron or Phosphorus Flashcards
What does iron react with to form rust?
Oxygen in the air
What will iron remove from the air?
Oxygen
What are the steps in doing this experiment?
- soak iron wool in acetic acid
- push wool into test tube
- thumb over end and invert tube into beaker of water
What will happen over time?
The level of the water in the test tube will rise
Why is this? (Water level)
The iron reacts with the oxygen in the air to make iron oxide - water rises to fill space oxygen took up
What do you need to do to work out the percentage of the air that is oxygen?
Mark the starting and finishing position of the water
What do you do after marking?
Fill the tube to each Mark with water and pour the contents into a measuring cylinder to find out the volume of air at the start and end
How do you work out the percentage of the starting volume that’s been used up?
Use the difference between the start and end volumes
What should the percentage be?
Around 20%
Why can you do a similar experiment with white phosphorus?
It smoulders in air to produce phosphorus oxide - calculate amount of oxygen same as iron
Look at apparatus page 37
Ok
