Pollutants and The Atmosphere Flashcards
Describe how the complete combustion of alkanes and alkenes involves the oxidation of the hydrocarbons to produce carbon dioxide and water
The complete combustion of alkanes and alkenes involves the
oxidation of hydrocarbons . Carbon dioxide and water are produced. For example:
Ethane + oxygen → carbon dioxide + water
Describe the complete combustion of hydrocarbon fuels as a reaction in which:
Complete combustion of a hydrocarbon fuel happens when there is a good supply of air. Carbon and hydrogen atoms in the fuel react with oxygen in an exothermic reaction:
carbon dioxide and water are produced
the maximum amount of energy is given out
Explain why the incomplete combustion of hydrocarbons can produce carbon and carbon monoxide
Incomplete combustion happens when the supply of air or oxygen is poor. Water is still produced, but carbon monoxide and carbon are produced as there not enough oxygen to create carbon dioxide/water. Less energy is released than during complete combustion.
Explain how carbon monoxide behaves as a toxic gas
Carbon monoxide is a poisonous gas which binds to haemoglobin in your red blood cells, preventing them from carrying oxygen to the cells in your body. Carbon monoxide is colourless and has no smell, so it is very difficult to tell if you are breathing it in.
Describe the problems caused by incomplete combustion producing carbon monoxide and soot in appliances that use carbon compounds as fuels
soot can block the pipes carrying away waste gases from an appliance. it blackens buildings and can cause breathing problems if it collects in the lungs
Explain how impurities in some hydrocarbon fuels result in the production of sulfur dioxide
Sulfur is an impurity in fossil fuels/hydrocarbons so when it is burned, the sulfur is let out, which combines with oxygen to make sulfur dioxide
Explain some problems associated with acid rain caused when…
… sulfur dioxide dissolves in water
acidic soil, killing plants
acidic lakes, killing fish
corrodes buildings/metal
Explain why, when fuels are burned in engines, ____ and _____ can react together at high temperatures to produce oxides of nitrogen, which are pollutants
oxygen nitrogen
This exceeds the activation energy of the reaction and nitrogen burns in the oxygen at these high temperatures, to make nitrogen oxides.
Recall that the gases produced by volcanic activity
formed the Earth’s early atmosphere
Describe that the Earth’s early atmosphere was thought to contain:
a little or no oxygen
and interpret evidence relating to this
-Volcanoes don’t produce oxygen
-Pyrite, a compound that is broken down by oxygen and so only forms if there is no oxygen - found in ancient rock.
-Rocks contained no iron oxide - later rocks contain iron oxide which is evidence that oxygen was released into the atmosphere and reacted with iron in rocks
Describe that the Earth’s early atmosphere was thought to contain:
a large amount of carbon dioxide
and interpret evidence relating to this
-Volcanoes affect the atmosphere by releasing large amount of some gases. Earth, Venus and Mars are rocky planets with volcanoes. Atmospheres of Mars and Venus are mainly carbon dioxide thought to be released by volcanoes - supports idea that Earth’s early atmosphere also contained lots of carbon dioxide.
Describe that the Earth’s early atmosphere was thought to contain
water vapour
and interpret evidence relating to this.
The Earth’s early atmosphere was thought to contain water vapour. About 4 billion years ago, the Earth cooled down. This caused water vapour to condense to liquid water which formed oceans.
Describe that the Earth’s early atmosphere was thought to contain:
small amounts of other gases
and interpret evidence relating to this.
The Earth’s early atmosphere was thought to contain small amounts of other gases. Evidence for this includes the mixture of gases released by volcanoes.
Explain how condensation of water vapour formed oceans
About 4 billion years ago, the Earth cooled down. This caused water vapour in the atmosphere to condense to liquid water and fell as rain to form the oceans.
Explain how the amount of carbon dioxide in the atmosphere was decreased when carbon dioxide dissolved as the oceans formed.
As the Earth cooled, oceans formed. Carbon dioxide then dissolved in the oceans, reducing the amount of carbon dioxide in the atmosphere. Sea creatures used the carbon dioxide to form shells made from calcium carbonate. This then allowed more carbon dioxide to dissolve in the oceans
Explain how the growth of primitive plants used ____ ________ and released ________ by photosynthesis and consequently the amount of oxygen in the atmosphere gradually increased
Primitive plants photosynthesised in order to make food from sunlight. Photosynthesis uses carbon dioxide and produces oxygen as a by product. As a result the increasing growth of primitive plants meant that the amount of oxygen in the atmosphere gradually increased.
Describe the chemical test for oxygen.
A glowing wooden splint relights in oxygen
Describe how various gases in the atmosphere, including carbon dioxide, methane and water vapour, ____ ____ radiated from the Earth, subsequently ____ ________ which keeps the Earth warm: this is known as the greenhouse effect.
Green house gases in the atmosphere, including carbon dioxide, methane and water vapour, absorb heat radiated from the Earth subsequently releasing energy which keeps the Earth warm. This is known as the greenhouse effect.
Evaluate the evidence for human activity causing climate change, considering:
the correlation between the change in atmospheric carbon dioxide concentration, the consumption of fossil fuels and temperature change
“CO2 absorbs infrared… data confirm that as CO2 levels have increased, there has been a reduction in infrared waves from the Earth leaving the atmosphere.”
Causal Relationship: The science presented points to a causal relationship: Increased CO2 due to human activities results in an increased greenhouse effect, which, in turn, increases global temperature.
Evaluate the evidence for human activity causing climate change, considering:
the uncertainties caused by the location where these measurements are taken and historical accuracy
Location of measurements:
some of the oldest temperature records are from Central England and this information goes back as far as 1659, before global temperature measurements existed.
Historical accuracy
Modern thermometers are less prone to error and have a greater resolution.
early thermometers had more potential for error and less resolution than modern day tools, indicating that older records may have had errors within them.
What is the composition of today’s atmosphere
78% nitrogen
21% oxygen
others:
0.9% argon
0.04% co2
the potential effects on the climate of increased levels of carbon dioxide and methane generated by human activity, including burning fossil fuels and livestock farming
livestock farming cows produces methane as cows have multiple stomachs and by eating the grass, which has many unwanted substances, they have to burp the methane out.
Burning fossil fuels will create carbon/carbon soot, if it’s doing incomplete combustion. But in complete combustion, there will be an excess amount of oxygen/air to make co2, which can create problems
Problems:
glaciers and polar ice melting
sea levels rising
rainfall changing, producing floods or droughts
habitats changing
Describe:
that these effects (of climate change) may be mitigated: consider scale, risk and environmental implications
These include:
building flood defences to manage floods from rivers and seas
building irrigation systems to provide water in droughts
planting different crops, better adapted to a new climate
These steps are expensive, need to be on a large scale, and may themselves harm the
environment
