C1 Flashcards
What is the air (or atmosphere)?
a mixture of gases
Other than N,O and Ar what does the atmosphere contain?
Water vapor and Carbon Dioxide.
Why are clouds and dust not part of the air?
Clouds are water or ice and dust is a solid.
Why is there a lot of empty space between gas molecules?
Particles are very small.
Why can gases be squeezed into a smaller volume?
because there is lots of space between gas molecules.
What does oxygen react with most metals to form?
solid metal oxides.
How can we find the percentage of oxygen in the air?
by passing air over heated copper.
When was the earth’s atmosphere formed?
4 billion years ago
What was the earth’s atmosphere formed by 4 billion years ago?
volcanos
What do volcanoes release?
huge amounts of carbon dioxide and water vapour (and lava and dust).
What are some processes that have removed almost all CO2 from the early atmosphere?
- 4 Billion years ago the Earth’s atmosphere was very hot.
- As the Earth cooled, oceans formed from the condensed water.
- About 3 million years ago simple bacteria-like creatures evolved using photosynthesis.
- This removed CO2 from the air, and released oxygen, allowing animals to evolve.
- CO2 was removed by plants and animals dying and becoming buried.
- Over millions of years some of the buried materials became fossil fuels.
- CO2 dissolved in oceans reacts with salts to form insoluble calcium carbonate.
- This forms sediments which become buried and cemented to form sedimentary rocks.
What did scientists believe about the composition of the Earth’s early atmosphere 60 years ago?
That the early atmosphere was largely ammonia and methane.
What have recent rock composition discoveries shown about the composition of the earth atmosphere?
That the early ideas were not correct and the early atmosphere was largely CO2.
Where are fuels used?
In factories, power stations, for transport and in homes.
What are pollutants?
gases that are harmful to health.
How are humans changing the gases in the atmosphere?
by burning fuels
What are some examples of pollutants?
Carbon monoxide, nitrogen oxides and sulfur dioxide.
What are pollutants harmful to?
the environment and to the people and animals living there.
What is ‘good’ and ‘poor’ air quality?
‘Good’ air quality is if it has very few pollutants.
‘Poor’ air quality is if it has lots of pollutants.
What does carbon monoxide reduce?
the amount of oxygen blood can carry.
What can burning fuels release?
Carbon dioxide and solid particulates that float in the air (e.g. carbon).
How are particulates released naturally?
as ash from volcanoes
In the last 50 years, by how much has the amount of CO2 increased by?
25%.
What does burning down forests to make more farmland do?
increases CO2 and particulates.
What happens when air pollution levels are high?
more deaths from asthma, heart disease and lung disease occur.
What pollutants cause acid rain?
sulfur dioxide and nitrogen dioxide.
What does acid rain damage?
plants and animals.
What negative effect on humans do sulfur dioxide and nitrogen oxides have?
asthma triggers.
What are small amounts of carbon dioxide in the air measured in?
parts per million (ppm).
What does 1ppm mean?
that there is 1 gram of the pollutant substance in 1 million grams of air.
What are other pollutant gases- Carbon monoxide, nitrogen oxides and sulfur dioxide measured in?
parts per billion (ppb).
What are the amount s of pollutant gases measured in?
air quality monitoring stations throughout the UK.
What is a correlation?
a link between a factor and an outcome.
What is needed to establish a casual link?
evidence to show that changing a particular factor is the only cause of a particular outcome.
What is needed for any fuel to burn and release energy?
Oxygen.
What is a hydrocarbon made up of?
only carbon and hydrogen atoms.
Fossil fuels such as petrol, diesel and fuel oil are mainly…
hydrocarbons.
What is coal?
a fossil fuel mainly made up of carbon atoms.
What is the equation for when a hydrocarbon fuel burns?
Hydrocarbon fuel + Oxygen —> Carbon dioxide + Water (+Energy).
What is oxidation?
when oxygen is added to a substance.
What is reduction?
when oxygen is removed from a substance.
What is combustion?
An oxidation reaction.
Can gases in the atmosphere be separated?
Yes
What does pure oxygen do when fuels burn?
makes them burn more rapidly and at higher temperatures.
What happens to elements in chemical reactions?
they are rearranged to make new compounds.
What happens to atoms in a chemical reaction?
they do not change. They get rearranged to make new substances.
What do non-metal elements join to form in chemical reactions?
molecules.
The numbers and types of elements in the reactants are the…
same as in the products.
Why is mass conserved in a reaction?
Because all the atoms in the reactants are just arranged into the products.
What does solid yellow sulfur burn to form?
a colorless gas called sulfur dioxide.
Is sulfur soluble?
no
What does sulfur dioxide dissolve in water to make?
an acid solution.
What do fossil fuels contain?
Small amounts of sulfur from the plants and animals that formed them.
Sulfur + oxygen —->
Sulfur dioxide
Why was it discovered that aquatic life was dying in the 1970s?
- Scientists were able to use data to explain that sulfur dioxide caused acid rain.
- Acid rain lowers to pH when it falls on land or enclosed water, harming living things or eroding carbonate rock.
Why is acid rain called an indirect pollutant?
Because it does not affect humans directly.
Why do power stations and transport make the most pollution?
because they burn the most fuel.
When fuel burns what is ALWAYS made?
CO2
When fuel burns, when is sulfur formed?
if the fuel burning contains sulfur.
If not enough air is available to burn the fuel:
- Poisonous carbon monoxide is made
- bits of solid carbon (soot) called particulates are made, making surfaces they land on dirty.
What do car engines produce?
nitrogen oxides when nitrogen and oxygen from the air react at high temperatures.
What do pollutants produced by car engines contribute to?
acid rain
Why do air quality measurements need repeating many times?
because results vary. On dry, hot and calm days, air pollutants can be trapped in cities.
Where is nitrogen monoxide formed?
in furnaces and engines are a temperature of about 1000 C.
What do different pollutants form and react with air to produce?
smog, acid rain & climate change.
What are carbon monoxide and particulate carbon formed during?
incomplete combustion
What happens when nitrogen monoxide is released into the atmosphere?
it cools. It then reacts with more oxygen to form toxic nitrogen dioxide, a brown gas.
Both NO and NO2 pollutants can be in the air and so what is used to represent both of them?
NOX
What does NOX damage?
buildings, contributes to acid rain and can affect health.
What do chemical formulae show?
how many atoms are joined together.
When are pollutants removed from the air?
- particulate carbon settles on surfaces and makes them dirty.
- sulfur and nitrogen oxides react wit water and oxygen to produce a mixture of sulfuric acid and nitric acid in rain (acid rain).
- carbon dioxide is used by plants for photosynthesis.
- carbon dioxide dissolved in rain water and in oceans.
What do climate scientists do?
They take the mean value of many measurements for each pollutant, which is a good estimate of a true value.
What does reducing electricity reduce?
fossil fuel use in power stations.
What do new electrical products use?
less electricity, bust some is wasted if they are left on standby.
What is a benefit of burning oil and gas over burning coal?
less sulfur dioxide is produced.
can sulfur be removed from oil and gas before it is burnt?
yes
Is it easy or hard to remove oil and gas from coal?
hard
What are power stations developing?
ways of reducing pollution by cleaning waste gases.
What do power stations use to remove solid particulates?
electrostatic filters.
How can sulfur dioxide be removed from waste gases?
flue gas desulfurisation.
What are the two ‘Wet scrubbing methods’ used to remove sulfur dioxide from power station waste gases?
- Using an alkaline slurry of calcium oxide(lime) and water to make gypsum (calsium sulfate), which can be sold as plaster.
- Using sea water, a natural alkaline which absorbs sulfur dioxide.
What does burning less fuel reduce?
the amount of carbon dioxide gas released.
What are some ways to reduce our use of fossil fuels?
- using alternative energy sources
- improving building insulation
- walking, cycling or using public transport.
What is an alternative to fossil fuels?
biofuels.
what is biofuel made from?
plans
What are some examples of biofuels?
wood chips, palm oil and alcohol made from sugar.
Biofuels are ‘carbon neutral’. What does this mean?
that when they are burned they release the same amount of CO2 that the plant originally took from the air to grow.
What is needed to grow biofuels?
large areas of land.
What needs to be done to meet the energy demand?
Less fossil fuels need to be burnt and alternatives need to be found. This will also reduce pollution.
What does gas produce less of than coal for the same amount of energy released?
CO2.
Fossil fuels are not renewable or…
sustainable.
Air pollution from vehicles can be reduced by:
- using cars less, especially for short journeys.
- using cleaner fuels and removing pollutants from exhausts.
- making public transport cheaper, more frequent and available in more places.
What do modern vehicles have?
more efficient engines that use less fuel.
what do catalytic converters contain?
a platinum catalyst that allows pollutant gases to react with eachother.
What is happening in the reaction between carbon monoxide and nitrogen monoxide, which produces nitrogen and carbon dioxide?
- Carbon monoxide gains oxygen so it is oxidized
- nitrogen monoxide loses oxygen so it is reduced.
What does low sulfur fuels reduce in public transport?
sulfur dioxide emissions.
what are enforced by strict MOT tests for cars?
legal limits for exhaust emissions.
What is one advantage and one disadvantage of electric cars in terms of pollution?
Advantage- they do not give out pollutant gases when being used.
Disadvantage- however, the electricity produced by fossil fuel power stations used for charging does.
