Fractional Distillation + Oxygen

Question 1

Steps to fractional distillation

Answer 1

1. Has to be condensed into a liquid. This happens at -200°C
2. At -200°C. Carbon dioxide and water are solid so can easily be taken out
3. Nitrogen boils at -196°C, so it can be removed from the top of the column as a gas
4. -185°C. Oxygen is still a liquid so can be taken out of the bottom of the column

Question 2

With what two methods can the percentage of oxygen be determined?

Answer 2

By burning some phosphorus/copper in a fixed volume of air

Question 3

How do you explain what happens when burning copper?

Answer 3

100 cm³ of air is in a syringe and is pushed across hot copper into the other syringe. Is passed backwards and forwards across the copper which turns black, the volume of all gets smaller and eventually stops getting smaller. The volume of remaining air is measured.