Air pollutants, catalytic converters and global warming
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The teaching part (1 min) is free to watch. A free account opens the whole lecture: 1 worked example, 4 practice questions, 2 real past-paper questions with the answers explained, the mistakes that lose marks, the full-marks tip, a one-card summary and a quick quiz.
What this lecture covers
- What comes out of the exhaust?
- Carbon monoxide
- Sulfur dioxide
- Oxides of nitrogen
Read the transcript of the teaching part
Last time
Before we start: last time, in Air, pollutants, global warming and photosynthesis, you learned these points. Here they are again on one card. Keep them in mind, because today builds on them.
What comes out of the exhaust?
Behind every car, bus and power station is a plume that you cannot always see. Some of its gases poison us, some make rain acidic, and some trap heat and warm the planet. Chemists know what each one is, where it comes from, and how to cut it.
Carbon monoxide
Carbon monoxide forms when fuels burn without enough oxygen. That is incomplete combustion. 2CH 4 plus 3O 2 gives 2CO plus 4H 2 O. It is toxic. It combines with haemoglobin in the blood, so the blood carries less oxygen. It is colourless and has no smell.
Sulfur dioxide
Fossil fuels contain sulfur. When they burn, S plus O 2 gives SO 2. Volcanoes make it too. It dissolves in rain to form acid rain. Acid rain damages trees and stonework, and harms life in lakes. It also causes breathing problems, especially for people with asthma. Acid rain attacks limestone: CaCO 3 plus H 2 SO 4 gives CaSO 4 plus H 2 O plus CO 2.
Oxides of nitrogen
In a car engine the temperature is high enough for nitrogen and oxygen in the air to react. N 2 plus O 2 gives 2NO. The nitrogen monoxide reacts with more oxygen to give nitrogen dioxide: 2NO plus O 2 gives 2NO 2. They cause acid rain and breathing problems.
How often it comes up
How often Cambridge has asked each part, counted by ExamYard from every past paper in its question bank: Greenhouse gases and global warming · Oxides of nitrogen and catalytic converters · Sources and effects of air pollutants · Air pollutants.
The whole chapter: Chemistry of the Environment, Chemistry of the Environment.
Chapter 10: Chemistry of the environment
- Clean air and photosynthesis 6 min
- Air pollutants, catalytic converters and global warming 5 min
- Water tests and domestic water treatment 5 min
Also for IGCSE Chemistry 0620
Which topics come up most in IGCSE Chemistry 0620 past papers, counted from every paper since 2004.