Air and Pollution 🧪 Flashcards
What is air a mixture of?
N2 78%
O2 21%
CO2 0.03-0.04%
All other gases (mainly Ar, Inert gases, Water Vapour and Dust) 1%
How is O2 obtained from air?
Dust is removed in a filter, air is compressed then allowed to expand from liquified air by fractional distillation oxygen is obtained
What happens when air is compressed then allowed to expand?
Water vapour is condensed and then freezes
Carbon dioxide becomes dry ice
What are polluted gases?
CH4 CO SO2 Hydrocarbons NO NO2
What gases do industries (coal) produce?
CO SO2 Nitrogen oxides
What gases do Vehicles produce?
Hydrocarbons, CO
How to remove SO2?
Ca(OH)2 aq lime water is sprayed neutralization reaction with SO2
How to remove CO NO NO2 and hydrocarbons?
Can be removed by fixing a catalytic converter which contains Pt and Rh catalysts. Fixed in the car exhaust pipe
What does a catalytic converter do?
Reactions take place and toxic gases which enter the converter come out as safe gases
What reactions take place in a catalytic converter?
2CO + O2 —> 2CO2
2CO + 2NO —> N2 + 2CO2
CxHy + O2 —> CO2 + H2O
How are oxides of Nitrogen produced in a vehicle?
When the engine heats up N2 combines with O2 in the air inside the engine to form oxides of nitrogen
When the vehicle runs for a short distance why are no Nitrogen oxides produced?
Engine doesn’t heat up enough, optimum temperature isn’t reached
What are the greenhouse gases?
CO2
CH4
SO2
What ability do these gases have?
They can trap I-R radiation and emits heat into the atmosphere. As a result the temperature of the atmosphere increases. This is called the greenhouse effect
What is the bad effect of SO2
Produces acid rain when it reacts with H2O and O2 which corrodes marble, stone and metals
