DF.10 Flashcards
Polluting gases
Why does product of combustion vary?
Products of combustion vary depending on oxygen availability and undergoes either complete or incomplete combustion.
What products are formed in complete combustion?
Carbon dioxide and water.
What are some possible products of incomplete combustion?
Carbon monoxide and carbon particulates.
What does the formula CxHy represent?
Unburnt hydrocarbon.
What polluting effects can particulates have?
Respiratory problems and other health issues.
What polluting effects can carbon monoxide have?
It is a toxic gas and can contribute to photochemical smog.
What is photochemical smog?
When primary pollutants undergo photochemical reaction by absorbing light energy and resulting in a mixture of primary and secondary pollutants.
What are some main green house gases?
- Carbon dioxide
- Methane
- Water vapour
- Nitrous oxide
- Ozone
How are oxides of nitrogen made during the combustion of fuels?
Nitrogen and oxygen in the air react when the engine is at a high temperature. Some nitrogen compounds may also be present in fuels but only in very low proportions.
How are oxides of sulfur made during the combustion of fuels?
Burning fuels that contain sulfur impurities.
What equation shows the production of nitrogen oxide in the car engine?
N2(g) + O2(g) → 2NO(g)
What polluting effects can nitrogen oxides have?
They are toxic and can cause acid rain.
What polluting effects can sulfur oxides have?
They are toxic and can cause acid rain.
Why are there sulfur impurities in fuels?
They are left from past amino acids in fossil fuels.
How do nitrogen oxides and sulfur oxides result in acid rain?
When they rise to the upper atmosphere, they react with water to form acids, either weak and strong, depending on the oxide.
What effects can acid rain have on the environment and the health?
Acid rain corrodes limestone buildings, kills forests and life in lakes, it also causes respiratory problems in people.
Apart from human activity, what is another major source of sulfur oxides?
Volcanic activity.
What are pollutants called that were made directly as a result of combustion of fuels?
Primary pollutants.
What are pollutants called when they are derived from primary pollutants in the atmosphere?
Secondary pollutants.
What effects can photochemical smog have on the environment and health?
Photochemical smog causes haziness and reduced visibility in the air, it also causes respiratory problems in people.
What reactions are sped up by catalysts in the engine?
Reactions to convert pollutants to compounds that are naturally present in air, such as carbon dioxide, water and nitrogen.
What is the equation for converting carbon monoxide to carbon dioxide?
2CO(g) + O2(g) → 2CO2(g)
What is the equation for reacting carbon monoxide and nitrogen oxide to form less polluting products?
2CO(g) + 2NO(g) → 2CO2(g) + N2(g)
How does the catalyst help remove unburned hydrocarbons?
Speeding up their complete combustion in oxygen.
What is the catalyst known as that speed up the three reactions that removed pollutants from the exhaust?
Three-way catalytic converter.
What are these catalytic converter normally consists of?
Platinum or with rhodium.
How can sulfur oxide pollutants be best prevented?
By removing sulfur impurities form the fuels before they are made available to motorists.
