Gases in the atmosphere Flashcards
What are the percentages of gases in the air
Nitrogen - 78%
Oxygen - 21%
Argon - 0.94%
Carbon dioxide- 0.04%
Other gases - traces
How do you separate gases in the air into their individual components
Fractional distillation of liquid air
Explain the idea behind Copper double syringe experiment
- The copper when heated reacts with all the oxygen within the syringe to form copper oxide
- This uses up all the oxygen in the gas syringe
- We can the work out the decrease in gas therefore we can figure out the percentage of oxygen in the air
How can you tell the reaction between the copper and oxygen had finished
When the volume of air no longer decreases
Why is the gas left for a few minutes to cool down
Air expands when heated to to get an accurate reading the air should cool down to original temperature
Describe what happens when phosphorus is set alight
A bright white light
Leaves a ashy grey solid
In the bell jar experiment why does the water level rise
Phosphorus reacts with all the oxygen in the air to form phosphorus oxide, so water flows into bell jar to replace the volume
Write the word and symbol equation between phosphorus and oxygen
Phosphorus + oxygen -> phosphorus oxide
4P + 5O2 -> P4O10
Explain the idea behind the iron wool experiment
Iron wool will react with the oxygen within the test tube and will start to rust and the water will get sucked up to replace the oxygen which is being used
In the iron wool experiment why is the teestube at an angle
It allows the water to be sucked into the test tube
Why could the percentage of oxygen be calculated too low
- Iron wool not wet enough
- Not enough iron wool used
- Not left long enough
Why could the percentage of oxygen could be calculated too high
- Some air escaped between the two high measurements
- Room temperature has increases causing air in test tube to expand.
What pH will metals have when dissolved in an acid and what ion makes them that pH
Acidic >7
H+ ions
What pH will non-metals have when dissolved in an acid and what ion makes them that pH
Alkaline <7
OH- ions
What is thermal decomposition
Breaking down a compound using heat
What is the equation when copper carbonate is thermally decomposed
Copper carbonate -> Copper Oxide + carbon dioxide
CuCO3 -> CuO + CO2
What so the colour change when heat is applied to Copper carbonate
Green to black
What would happen to the mass of Copper carbonate as heat is applied
Mass would decrease as CO2 gas escapes
What are the properties of CO2
- Higher density then air
- Soluble in water
- Plants need CO2 for photosynthesis
What is a fuel
A substance that when burned releases heat energy
What is combustion
the reaction with oxygen to produce heat (and light) energy
When does complete combustion occur
When there is an excess of oxygen
What are the products of complete combustion
Produces carbon dioxide and water
Released more heat energy per gram of fuel
When does incomplete combustion occur
Insufficient oxygen
What are the products of incomplete combustion
Carbon (soot), water and carbon monoxide
What is carbon monoxide and why is it dangerous
Carbon monoxide is a colourless, odourless, toxic gas and it combines irreversibly with haemoglobin so reduces bloods capacity to carry oxygen
What is the test for water
Blue colbalt chloride paper turns pink
What are the effects on the world when carbon goes through incomplete combustion
- Carbon (soot) :
This causes global dimming, photochemical smog and blackens buildings - Carbon monoxide
This is toxic and reduces the blood’s capacity to carry oxygen
What are the effects on the world when carbon undergoes complete combustion
-Carbon dioxide is formed
This is a greenhouse gas and causes global warming and ice caps to melt
Where is sulphur found and how does it become SO2
Sulphur is an impurity in fossil fuels and it burns in O2 to form SO2
(S+O2 ->SO2)
What effect does SO2 have on the environment (give equation)
SO2 dissolves in water to form acid rain
(SO2 +H2O -> H2SO3)
Sulfurous acid
How can we stop sulfur dioxide forming
Petrol can be desulferised before it is used
How is nitrogen oxide formed
Formed in the internal combustion engine when there are high temperatures and a spark
Write the equations for nitrogen monoxide and nitrogen dioxide
N2 + O2 -> 2NO
2NO +O2 -> 2NO2
How does nitrogen oxide effect the environment and give an equation
Nitrogen monoxide reacts with more oxygen and rainwater to form acid rain
NO2 + H2O -> HNO2
How can we prevent nitrogen oxides from entering the air
Using a catalytic converter
