BOTH P1+2 2c gases in the atmosphere Flashcards
(28 cards)
what are the four most abundant gases in unpolluted dry air?
nitrogen
oxygen
argon
carbon dioxide
what is the percentage of nitrogen in the air?
78.1%
what is the percentage of oxygen in the air?
21.0%
what is the percentage of argon in the air?
0.9%
what is the percentage of carbon dioxide in the air?
0.04%
what is the remainder made up of?
other noble gases such as helium
how do you measure the percentage of oxygen in the air?
three experiments that are used to measure the percentage of oxygen in the air
- reaction of a substance with oxygen in the air
- the substances are copper, iron and phosphorus
what is the experiment to measure the % of oxygen in the air, by reacting it with copper?
two gas syringes on either side od a silica tube packed with copper filings.
- the copper is heated (to create a combustion reaction)
- the gas syringe with 100cm^3 of air in it will move forward as the copper is burned
- this shows the amount of oxygen used in the reaction
- when it has stopped moving the reaction has stopped
- then figure out the percentage change
what is the experiment to measure the % of oxygen in the air, by reacting it with iron?
a gas syringe is connected to a conical flask which has wet iron filings in it
- the volume of air decreases as the oxygen is removed as it reacts with iron to form rust
- it may need to be left for a week, so the reaction can be completed
what is the experiment to measure the % of oxygen in the air, by reacting it with phosphorus?
a trough is half filled with water, then an evaporating basin with phosphorus is placed on the water, over the basin a bell jar is placed.
- light phosphorus on fire and it will react with oxygen, the water level in the bell jar rises
- by determining how much the water has risen by it will show the oxygen in the air
- this is a displacement of water
what happens in the combustion of magnesium?
the silver ribbon of metal burns in oxygen to form magnesium oxide
- it will burn with a bright white flame
- it will turn into a bight white flame
what is the symbol equation for the combustion of magnesium?
2Mg(s) + O2(g) -> 2MgO(s)
what happens when MgO reacts with water?
it forms magnesium hydroxide
which is an alkaline
what happens in the combustion of sulphur?
the yellow powder burns in oxygen a colourless gas with a blue flame to form sulphur dioxide
what is the symbol equation for the combustion of sulphur?
S(s) + O2(g) -> SO2(g)
what happens when SO2 reacts with water?
it forms an acidic solution, of sulphurous acid
what happens in the combustion of hydrogen?
hydrogen burns in oxygen with a pale blue flame to form water
what is the symbol equation for the combustion of hydrogen?
2H2(g) + O2(g) -> 2H2O(l)
what is thermal decomposition?
reactions where a substance breaks down due to the action of heat
what is the reaction for decomposition of the lower half of the reactivity series?
metal carbonate -> metal oxide + carbon dioxide
describe the thermal decomposition of copper (II) carbonate.
copper(II) carbonate is a green powder and slowly darkens as black copper(II) oxide is produced
- there is carbon dioxide given off
what is the equation for the thermal decomposition of copper(II) carbonate?
CuCO3 (s) -> CuO (s) + CO2 (g)
copper (II) carbonate -> copper (II) oxide + carbon dioxide
how does the production of cement effect the atmospheric CO2 levels?
in the production of cement there is a release of carbon dioxide from the calcium carbonate, which adds CO2 and therefore contributes to the enhanced greenhouse effect
what are the sources of carbon dioxide, in the atmosphere?
- combustion of wood and fossil fuels
- respiration of plants and animals
- thermal decomposition of carbonate rocks
- the effect of acids on carbonates
