Pollutants from Burning Fuels
Hydrocarbon combustion can produce carbon dioxide, water, carbon monoxide and soot. Sulfur impurities can form sulfur dioxide, while high engine temperatures let nitrogen and oxygen from air react to form nitrogen oxides.
What a learner can do afterwards
- Names products of complete and incomplete hydrocarbon combustion, explains the harms of carbon dioxide, carbon monoxide and soot, and identifies safe action when carbon monoxide is suspected
- Explains where sulfur dioxide comes from and how it ends up as acid rain
- Explains why nitrogen oxides form in an engine when nitrogen is normally unreactive
- Evaluates one measure that cuts a named pollutant and says what it costs
1 · Read
Complete hydrocarbon combustion with enough oxygen produces carbon dioxide and water. Extra carbon dioxide contributes to climate change. Limited oxygen can produce carbon monoxide, soot and water, alongside carbon dioxide or unburned fuel. Carbon monoxide is colourless, odourless and poisonous. It binds to haemoglobin and reduces the blood's ability to carry oxygen. Soot particles can harm breathing and health.
Some fuels contain sulfur impurities. Burning sulfur forms sulfur dioxide, SO2. In the atmosphere, it can dissolve and react to form acids that fall in rain. Acid rain can damage plants, acidify lakes and attack limestone buildings. Winds can carry the gases far from their source. Sulfur dioxide also irritates the airways.
Air contains nitrogen and oxygen. Nitrogen is normally unreactive, but very high engine temperatures allow these gases to react chemically, forming nitrogen oxides, NOx. These gases irritate the airways, contribute to photochemical smog and can form acids that contribute to acid rain. Still weather can let pollutants build up near their sources.
Soot near a fuel-burning appliance, headaches or dizziness can warn of danger, but do not prove a diagnosis. If carbon monoxide is suspected, leave for fresh air immediately, tell an adult and get emergency help. Do not stay to test the flame or return until professionals say it is safe. Working carbon monoxide alarms and properly maintained appliances help protect people.
Match controls to pollutants. Catalytic converters can reduce carbon monoxide, nitrogen oxides and unburned hydrocarbons in vehicle exhaust. A catalyst is a substance that speeds up a chemical reaction by lowering the activation energy needed to start it, and the catalyst itself is not used up. A catalytic converter holds catalysts that speed up reactions turning harmful exhaust gases into less harmful ones. Power-plant scrubbers remove sulfur dioxide from flue gas, often using alkaline material such as limestone. Lower-sulfur fuels reduce the SO2 formed. Controls have equipment, processing or maintenance costs; scrubbers also need energy to run.
Limited oxygen can form CO and soot. Fuel sulfur can form SO2; hot air reactions form NOx. Match controls to pollutants and act safely around suspected CO.
Lesson, questions and flashcards written for this dataset.
Readings and flashcards written for this dataset.
More to read
Responding to suspected carbon monoxide
A normal-looking flame cannot establish that a fuel-burning appliance is safe. Carbon monoxide has no colour or smell. It binds to haemoglobin and reduces the blood's ability to carry oxygen.
Headaches, dizziness or soot near an appliance can warn of danger, but symptoms alone do not establish the cause. If carbon monoxide is suspected, leave for fresh air immediately, tell an adult and get emergency help. Do not remain beside the appliance to investigate. Return only when professionals say it is safe.
Working CO alarms and properly maintained appliances help protect people.
Find the pollutant's source
Start with the ingredients when tracing combustion pollutants. Fuel carbon can form carbon dioxide, carbon monoxide or soot. Fuel sulfur can form sulfur dioxide. At very high engine temperatures, nitrogen and oxygen taken in from air can react to form nitrogen oxides.
A control must target the relevant source or product. Lower-sulfur fuel reduces the sulfur available to form SO2. Catalytic converters can reduce CO, nitrogen oxides and unburned hydrocarbons in exhaust. A catalyst is a substance that speeds up a chemical reaction by lowering the activation energy needed to start it, and the catalyst itself is not used up.
Reducing one pollutant does not establish that every pollutant has been removed.
Compare a control's benefit and cost
A scrubber treats flue gas before it leaves a power plant. It removes sulfur dioxide, often using an alkaline material such as limestone. This reduces emissions but needs equipment, materials, maintenance and energy.
The benefit matters beyond the chimney. Sulfur dioxide can undergo atmospheric reactions that form acids. Rain carries acids to land and water, where they can damage plants, acidify lakes and attack limestone. Winds may carry the gases far from their source.
When evaluating a control, name the pollutant reduced and a real cost. Avoid claiming that one device removes all pollution.
2 · Watch
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