Gases in the atmosphere Flashcards
What are the approximate percentages of gases in the air?
Nitrogen: 78.1
Oxygen: 21
Argon: 0.9
Carbon: 0.04
Using experiments to determine the percentage by volume of oxygen in the air.
A piece of phosphorus was placed in a dish. The dish was placed on the water in a trough and it floated. A bell jar then was placed on top of the floating dish and the height of the water on the bell jar was measured. The phosphorus was then set on fire. When the phosphorus was done burning, the height of the water was measured again. Subtract the height of the bell jar from the start and end water level. Then subtract those results from each other. The answer you get you to have to divide by the Height of the bell jar - the starting level. Times that by a hundred and you have the oxygen level.
100 cm3 of air was passed from side to side over copper that was being heated by the bunsen burner. All the oxygen will react with copper. As it passed through the air the volume decreased and was left at 79.
Combustion of elements in oxygen
Magnesium: Burns in oxygen with an extremely bright white flame to give a white powdery magnesium oxide.
Sulfur: Burns with a blue flame. Sulfur oxide is formed. Dissolves in water to form an acidic solution.
Hydrogen: Burns with a pale blue flame. The product is water.
Thermal Decomposition
Most carbonates split to give the metal oxide and carbon dioxide when you heat them. This is an example of thermal decomposition. Copper (II) carbonate is a green powder that decomposes on heating to produce black copper (11) oxide.
Carbon dioxide and greenhouse gases
C02 has been increasing since the burning of fossil fuels and deforestation. IR radiation is absorbed by CO2 which then gives out the energy again in all directions heating the atmosphere.
