Topic 8- Fuels & Health Science 📄📄 Flashcards
What are the 4 layers of the earth?
- Crust- thin and rocky
- Mantle- largest part
- Outer core- liquid iron and nickel
- Inner core- solid iron and nickel
Why is the outer core liquid but the inner core solid?
The inner core is subject to high pressure which forces the particles together
What is in earths atmosphere today? (3 inc. %)
- Nitrogen at 78%
- Oxygen at 21%
- Other including argon, water vapour and carbon dioxide at 1%
The levels of oxygen in the atmosphere increased because …
Plants and algae evolved and photosynthesised which released oxygen
The levels of water vapour have decreased because…
Water vapour condensed to form the oceans since Earths temperature cooled
The levels of carbon dioxide decreased because…
Photosynthesis occurred which absorbed carbon dioxide and released oxygen and carbon dioxide dissolved into the oceans
The levels of carbon dioxide have started to increase because…
The burning of fossil fuels, the use of fossil fuels in factories and cars, C02 in the sedimentary rock being released and deforestation (less trees to absorb C02)
Complete combustion of methane word equation:
Methane + Oxygen —> Carbon dioxide + Water
What is the issue associated with Carbon? (4)
Soot blackens buildings
Causes breathing problems
May block appliances
Cause fires
What is the issue associated with Carbon monoxide?
Toxic gas which combines with haemoglobin in red blood cells which prevents oxygen combining therefore reducing the amount of oxygen in the bloodstream leading the person being sleepy, unconscious and it can lead to death
What is the issue associated with carbon dioxide? (2)
Contributes to global warming/climate change and damages the land/air/water
Alkanes are a family of
Hydrocarbons
Alkanes all end in
ane
Formula for alkanes
CnH2n+2
Bonds in alkanes
Alkanes form a single bond between carbon atoms
Bonds in alkenes
Form at least one double bond between 2 carbon atoms
Each carbon atom has
4 bonds
For alkenes all names end in
ene
General formula for alkenes
CnHn
Examples of alkanes
Methane, ethane, butane, propane
Examples of alkenes
Ethene, propene, butene, Pentene,
How do you test for alkanes/alkenes?
- Add bromine to an unknown hydrocarbon
- If the bromine water stays brown, the hydrocarbon is an alkane
- If the water turns colourless, the hydrocarbon is an alkene
What is an unsaturated hydrocarbon?
A hydrocarbon that contains a double bond
What is cracking?
The breaking down of long chain hydrocarbons into shorter chain hydrocarbons using heat and a catalyst
An alkane and an alkene
What is cracking?
The breaking down of long chain hydrocarbons into shorter chain hydrocarbons
An alkane and an alkene
What does cracking always produce?
1 Alkane and 1 Alkene
What is crude oil?
A complex mixture of hydrocarbons
Contains molecules with rings or chains of carbon atoms
What is an important source of useful, substances like fuels and feedstocks for the petrochemical industry?
Crude oil
Where can crude oil be found?
Under the sea and ground
How can crude oil be separated?
Fractional distillation
How does the process of fractional distillation work to separate crude oil?
Crude oil is vaporised before it enters a fractionating column.
The fractionating column is hotter at the bottom than at the top. The vapours rise up and condense at different fractions depending on their boiling points.
Hydrocarbons with low boiling points will be tapped off the top of the column and hydrocarbons with high boiling points will be tapped off the bottom of the column.
Why is crude oil separated?
Separated products are more useful
What is refinery gas, from crude oil, used for?
Heating and cooking
What is kerosene used for?
Aircraft fuel
Hat fraction of crude oil is used for road surfacing and roofs?
Bitumen
How do the hydrocarbons at each faction differ? (4)
Boiling points
Ease of ignition
Viscosity
The number of hydrocarbons and carbon atoms their molecules have
What is viscosity ?
How thick or sticky a substance is.
What are the only products when a hydrocarbon fuel goes under complete combustion?
Water and carbon dioxide
True or false? Energy is given out when a fuel undergoes complete combustion
TRUE
The reaction is exothermic
When does incomplete combustion occur? What is required to ensure complete combustion occurs?
Incomplete combustion occurs when there is an insufficient supply of oxygen
To ensure complete combustion occurs, the reaction should be carried out with excess oxygen
What are the products of incomplete combustion?
Carbon particulates - soot
Carbon monoxide
Water
What re the problems with carbon monoxide?
Carbon monoxide is a toxic gas
It’s is colourless and odourless and if breathed in can cause death by preventing the red blood cells from carrying oxygen around
What are the problems with incomplete combustion?
Produces carbon monoxide which is toxic and can be fatal if breathed in
Produces carbon particulates which causes global dimming and respiratory problems
Why is Sulfur dioxide sometimes produced when burning hydrocarbon fuels?
Some hydrocarbon fuels contain Sulfur impurities
When the fuel is burned, the Sulfur reacts with oxygen to form Sulfur dioxide
Why is Sulfur dioxide sometimes produced when burning hydrocarbon fuels?
Some hydrocarbon fuels contain Sulfur impurities
When the fuel is burned, the Sulfur reacts with oxygen to form Sulfur dioxide
How is acid rain produced?
Sulfur dioxide evaporates into the air. It’s reacts with water in the clouds to form Sulfur is acid. This is acid rain
What problems can acid rain cause?
Corrodes buildings and statues made of limestone
Kills and damages vegetation
Lowers the pH of large bodies of water and killing the wildlife
How are oxides of nitrogen produced from car engines.
The high temperature and pressure of a car engine causes nitrogen and oxygen from the air react together
What are problems associated with oxides of nitrogen ?
Pollutants
Produce acid rain
Causes respiratory problems
What are the advantages of using hydrocarbons as a fuel in cars?
It relates more energy per kg compared to most other fuels
Water is the only product so no pollutants
Renewable source as hydrogen can be extracted from water
What are the disadvantages of using hydrogen as a fuel in cars?
It is expensive to produce and a lot of energy is required for the electrolysis of water to acquire the hydrogen
Difficult and dangerous to store hydrogen because it is very volatile and easily ignited
Name the non renewable fossil fuel found in natural gas
Methane
What does saturated mean?
Only contains single bonds
What does unsaturated mean?
Contains some double bonds
What type of reaction is cracking?
Thermal decomposition
What is the chemical test for oxygen?
Insert a glowing splint into a test tube of Beas. If the oxygen is present, the splint will ignite
What is the greenhouse effect? Process
Electromagnetic radiation from the sun passes through the Earth’s atmosphere.
- The Earth absorbs some radiation and warms up.
- Heat is radiated from the Earth as infrared radiation.
- Some of the infrared radiation is absorbed by greenhouse gases in the atmosphere which warms the atmosphere
How has human activity increased atmospheric carbon dioxide concentration?
Burning fossil fuels for energy releases CO2
Deforestation reduces the amount of photosynthesis occurs so less carbon dioxide is converted to oxygen
Evaluate the evidence that human activity is causing climate change:
There is a correlation between carbon dioxide concentration in the atmosphere, fossil fuel consumption and temperature change.
- Correlation doesn’t mean causation.
- There may be uncertainties in the data (e.g. location of the measurements and historical accuracy).
What are some effects of global warming?
Melting of polar ice caps
Difficulties acquiring drinking water
Flooding
Forest fires
Destruction of ecosystems
How has human activity increased the amount of methane in the atmosphere?
Raising livestock such as cows
Decay of organic waste in landfill sites
How can the effects of global warming be mitigated?
Construction flood defences in areas of low lying land
Use of irrigation systems to provide water in drought
Produce alternative crops which are breed adapted to the new environment
