Gases in the Atmosphere Flashcards
What is the percentage of nitrogen in the atmosphere?
78%
What is the percentage of oxygen in the atmosphere?
21%
What is the percentage of argon in the atmosphere?
0.9%
What is the percentage of carbon dioxide in the atmosphere?
0.04%
What is the percentage of other gases in the atmosphere?
0.06%
What is the method to investigate the proportion of oxygen in the atmosphere?
- first soak some iron wool in acetic acid (the acid will catalyse the reaction). Then push the wool into a measuring cylinder and invert the measuring cylinder into a beaker of water
- record the starting position of the water using the scale on the measuring cylinder- this is the start volume of air.
- over time the level if the water in the measuring cylinder will rise
- this is because iron reacts with oxygen in the air to make iron oxide. the water rises to fill the space the oxygen took up
- leave the measuring cylinder for about a week or until the water stops changing
- record the finishing position of the water (this is the final volume of air)
How can you calculate the percentage of oxygen?
start volume- final volume/start volume X 100
How can you use phosphorus to determine the percentage of oxygen in the air?
- place the phosphorus in a tube and attach glass syringe either end
- make sure one of the syringes is filled with air and the other is empty
- heat the phosphorus and use the syringes to pass the air over it- the phosphorus will react with oxygen in the air to make phosphorus oxide
- as it reacts, the amount of air in the syringes will decrease
- measure the starting point and final volume of air using the scale on one the syringes
- you can then calculate the percentage of oxygen in the air using the formula above
What happens as you burn magnesium?
- magnesium burns with a bright white flame in air and the white powder that is formed is magnesium oxide
- magnesium oxide is slightly alkaline when its dissolved in water
What happens as you burn hydrogen?
- hydrogen burns very easily in oxygen, in fact it can be explosive
- it has an almost invisible pale blue flame and the only product is water
- the combustion of hydrogen is often used as a test for hydrogen gas
- in small amounts the resulting explosion gives the characteristic “squeaky pop”
What happens as you burn sulfur?
- sulfur burns in air or oxygen with a pale blue flame and produce sulfur dioxide
- sulfur dioxide is acidic when its dissolved in water
What produces if you heat a metal carbonate?
- you get carbon dioxide and a metal oxide
What is thermal decomposition?
- (when heating a metal carbonate you get carbon dioxide and a metal oxide)
- when a substance breaks down into a simpler substance when heated
What will happen to copper (II) carbonate as you heat it?
- copper carbonate is a green powder that will easily decompose to form carbon dioxide and copper (II) oxide when you heat it
What is the word and symbol equation for the thermal decomposition of copper (II) carbonate?
CuCO = CuO + CO
copper (II) carbonate = copper oxide + carbon dioxide
How can you do the experiment to see if carbon dioxide is present in copper carbonate?
- heat copper carbonate then collect the gas thats given off in the test tube
- the gas that’s collected can be then tested to see if it is carbon dioxide … using limewater
What do gases in the atmosphere act as and what are they?
- carbon dioxide
- methane
- water vapor
- all act as an insulating layer
- they are often called green house gases
What is the temperature of the earth a balance between?
- the heat it gets from the sun and the heat it radiates back into space
What is two examples of where human activity affects the amount of carbon dioxide in the atmosphere?
- deforestation: fewer trees means less carbon dioxide is removed from the atmosphere via photosynthesis
- burning fossil fuels: carbon that was “locked up” in these fuels is being released as C02
- it is because of this human activity that the concentration of CO2 in the atmosphere has been increasing. C02 must have been released into the air faster than it is being removed
What is global warming?
- a type of climate change and causes other types of climate change
- there is a correlation between increasing levels of CO2 and the gradual heating up of the earths atmosphere
