Oxygen and the Air Flashcards
which gases present in the air and what is their approximate percentage?
Nitrogen- 78%
Oxygen- 21%
Argon- 0.9%
Carbon dioxide- 0.04%
describe how experiments involving the reactions of elements such as copper, iron and phosphorus with air can be used to determine the percentage by volume of oxygen in air
An experiment was carried out to find the percentage of air that is oxygen. 100 cm3 of air was passed from side to side over copper that was being heated with a Bunsen. All the oxygen in the air will react with the copper. No air could get in or out of the system while it was passed to and fro between the syringes. As it was passed to and fro, the volume of air went down. It was passed until the volume stopped decreasing, and a few minutes later the volume of remaining air was recorded. There was 79 cm3 left. This shows that 21cm3 of the original 100cm3 of air was oxygen, because it was the oxygen that reacted with the copper to form black copper oxide. During this experiment, you should see the copper go black as it forms copper (II) oxide.
copper + oxygen à copper (II) oxide
2Cu (s) + O2 (g) à 2CuO (s)
understand that nitrogen oxides and sulfur dioxide are pollutant gases which contribute to acid rain, and describe the problems caused by acid rain
NO and SO2 are given off into the atmosphere by some industrial processes.
When they are in the atmosphere they react with rain water to create H+ ions.
When the rain falls the acid can corrode rocks and buildings. Acid can also alter the PH in soil or rivers which can effect an ecosystem.
Also acid rain corrodes limestone, which damages buildings and stuff.
