Air Quality & Climate (Cambridge (CIE) IGCSE Co-ordinated Sciences (Double Award): Chemistry): Flashcards
Exam code: 0654 & 0973
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What is the source of carbon monoxide as an air pollutant, and why is it dangerous?
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What is the source of carbon monoxide as an air pollutant, and why is it dangerous?
Carbon monoxide comes from the incomplete combustion of carbon-containing fuels.
It is toxic because it combines with haemoglobin in the blood and prevents it from carrying oxygen.
Clean, dry air contains approximately ______% nitrogen and ______% oxygen, with the remainder being noble gases and carbon dioxide.
Clean, dry air contains approximately 78% nitrogen and 21% oxygen, with the remainder being noble gases and carbon dioxide.
State two sources of methane as an air pollutant.
Methane comes from waste gases produced during digestion in animals and from the decomposition of vegetation. It is also released by bacterial action in swamps, rice paddy fields and landfill sites.
True or False?
Both sulfur dioxide and oxides of nitrogen contribute to acid rain.
True.
Both sulfur dioxide and oxides of nitrogen dissolve in rainwater to form acid rain, which damages metal structures, carbonate buildings and aquatic ecosystems.
What are the products of complete combustion and incomplete combustion of a hydrocarbon fuel?
Complete combustion in excess oxygen produces carbon dioxide and water.
Incomplete combustion in limited oxygen produces carbon monoxide and water, and may also produce particulates of carbon (soot).
Where do oxides of nitrogen form, and what adverse effects do they have?
Oxides of nitrogen form in car engines, where high temperatures cause nitrogen and oxygen in the air to react.
Their adverse effects include producing acid rain and causing respiratory problems.
Particulates are produced by the ______ combustion of carbon-containing fuels and can cause ______ problems and cancer.
Particulates are produced by the incomplete combustion of carbon-containing fuels and can cause respiratory problems and cancer.
How do greenhouse gases cause global warming?
Greenhouse gases such as carbon dioxide and methane absorb thermal energy radiated from the Earth's surface. They then re-emit this thermal energy in all directions, reducing the amount lost to space and keeping the Earth warm.
The two main greenhouse gases responsible for global warming are ______ and ______.
The two main greenhouse gases responsible for global warming are carbon dioxide and methane.
What is the enhanced greenhouse effect?
The enhanced greenhouse effect occurs when human activities increase the concentration of greenhouse gases in the atmosphere. More thermal energy is trapped, causing the Earth's average temperature to rise — a process called global warming.
State three consequences of global warming.
Consequences of global warming include:
Rising sea levels as glaciers melt causing flooding in low-lying areas
Extinction of species due to destruction of natural habitats
The spread of diseases in a warmer climate.
True or False?
Greenhouse gases reflect all of the Sun's energy back into space before it reaches the Earth's surface.
False.
Greenhouse gases absorb thermal energy re-emitted from the Earth's surface and re-emit it in all directions. This traps heat in the atmosphere rather than allowing it to escape to space.
Why does an increase in atmospheric carbon dioxide lead to a rise in the Earth's temperature?
Carbon dioxide absorbs thermal energy radiated from the Earth's surface and re-emits it in all directions. This reduces the amount of thermal energy lost to space, so more heat is retained in the atmosphere and the Earth's temperature rises.
State two strategies to reduce the effects of climate change by reducing carbon dioxide emissions.
Strategies to reduce carbon dioxide emissions include:
Decreasing the use of fossil fuels
Increasing the use of hydrogen and renewable energy sources such as wind and solar
Planting more trees to absorb carbon dioxide through photosynthesis.
Sulfur dioxide emissions can be reduced by using ______-sulfur fuels and by ______ gas desulfurisation.
Sulfur dioxide emissions can be reduced by using low-sulfur fuels and by flue gas desulfurisation.
How do catalytic converters reduce air pollution from car exhaust gases?
Catalytic converters contain transition metal catalysts, including platinum and rhodium, arranged in a honeycomb to maximise surface area. Carbon monoxide is oxidised to carbon dioxide, and oxides of nitrogen are reduced to nitrogen gas via redox reactions.
True or False?
Planting trees reduces atmospheric carbon dioxide by increasing the rate at which carbon dioxide is removed through photosynthesis.
True.
Trees absorb carbon dioxide during photosynthesis, so planting more trees (or preventing deforestation) increases the rate of carbon dioxide removal from the atmosphere.
What is the balanced equation for the reaction of carbon monoxide and nitrogen monoxide in a catalytic converter?
Carbon monoxide is oxidised to carbon dioxide and nitrogen monoxide is reduced to nitrogen gas:
2CO + 2NO → 2CO2 + N2
In flue gas desulfurisation, waste gases are sprayed with a slurry of ______ oxide and calcium carbonate, which reacts with sulfur dioxide to produce calcium ______.
In flue gas desulfurisation, waste gases are sprayed with a slurry of calcium oxide and calcium carbonate, which reacts with sulfur dioxide to produce calcium sulfate.
Why is reducing livestock farming a strategy for tackling climate change?
Reducing livestock farming decreases methane emissions, as methane is produced during digestion in animals. Methane is a greenhouse gas that contributes to global warming.
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