Chemistry - C3

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  • Created by: L_Georgie
  • Created on: 20-03-16 15:46
What is the first layer on earth and what is it made up of?
The first layer is called the crust and it is made up of tectonic plates that 'float' on the mantle.
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What are the other layers that are found under the earth's crust/
The mantle, outer core and then inner core. The core is made out of iron and nickel.
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What provides evidence that the tectonic plates are moving?
Sea floor spreading and the magnetic marks left in the rocks.
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Why are fossils good evidence for finding out what earth used to be like/
Fossils are good because they tell you about the age of the rock and well as the conditions it was formed under.
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Where do chemical industries tend to get set up?
They get set up where useful mineral resources can be found.
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Through what processes are minerals formed?
Sedimentation, dissolving, evaporation, erosion and mountain building.
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What are sedimentary rocks formed by?
They are formed from layers of sediment laid down in lakes or seas.
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What is erosion?
Erosion is the natural weathering of large pieces of rock in rain and wind.
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What happens when the sediment is buried under more layers?
The weight pressing down squeezes out the water and then fluid flowing through pores in the sediment deposit natural mineral cement that holds the sediments together.
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What is rock salt?
Rock salt is a mixture of salt and impurities that is found in underground deposits.
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What happens in normal salt mining?
The rock salt is drilled, blasted and dug out and brought to the surface using machinery.
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What is the rock salt harvested from normal salt mining used for?
The rock salt is used as grit for roads or it can be separated out and used to enhance the flavour of food or for making other chemicals.
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How does rock salt stop ice forming and help keep drivers safe?
It lowers the freezing point of water to about -5. It also adds extra grip for cars when travelling on the road.
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How do they get the salt out from underground in salt solution mining?
They inject water into the salt deposit underground with a pipe, this dissolves the salt and makes a brine. Pressure forces the brine up a separate pipe to the surface.
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What do they do after they have got the brine up to the surface?
They sort it into wells and it is then pumped to a refining plant. They then remove the impurities from the brine and evaporate it leaving the salt behind.
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What is the salt produced from salt solution mining used for?
Table salt and chemical production.
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What are some of the environmental issues with normal salt mining?
Subsidence, the land above a mine could collapse into the mine. Also because mining uses a lot of energy a lot of fossil fuels are often burnt.
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How can salt be obtained from the sea?
Through evaporation. Seawater flows into specially built shallow pools where it is left to evaporate in the sun which would leave the salt behind.
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Which method of getting salt produces the purest salt?
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What are the uses of salt in food production?
Salt can be added as a preservative and it can be used to enhance the flavour of something.
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How does the salt preserve food like meat?
When salt is added to meat it dries out the meat by absorbing the water from it and any bacterial cells. This kills the bacteria and preserves the meat.
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What is the major health issue with salt?
It can cause high blood pressure which can lead to strokes and heart attacks. There is also evidence saying that salt could cause stomach cancer and renal failure.
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What have governments done regarding salt intake?
They have produced guidelines to show the maximum daily amount of salt that people should have in a day depending on their age.
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What is the department of healths function?
To carry out risk assessments for chemicals in food to make sure they are safe and to advise the public about how food effects their health.
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Why might food manufacturers still include salt in their products even if it is unhealthy?
The cost of reformulating recipes may be too high. Also if they include less salt the product may not taste as good and so the sales may go down.
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Why is salt important for the chemical industry?
Because they can electrolyse the salt solution (brine) causing a chemical change and splitting it into hydrogen, chlorine and sodium hydroxide.
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What can chlorine be used in?
Disinfectants, killing bacteria, household bleach, plastics, hydrochloric acid and insecticides.
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What can hydrogen be used for?
Used to make ammonia, used to change oils into fats for making margarine and used as fuel.
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What can sodium chloride be used in?
Soap, oven cleaner, ceramics, organic chemicals, household bleach and paper pulp.
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What are the environmental issues with electrolysis?
A lot of energy is needed so a lot of fossil fuels are burnt, mercury is often used in electrolysis and this is a toxic chemical and asbestos is also used in electrolysis.
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Why is chlorine added to the UK's water supply?
It kills disease-causing microorganisms and it prevents the growth of algae, gets rid of bad tastes and smells and it removes discolouration caused by organic compounds.
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How can chlorine be made?
Chlorine can be made by electrolysing brine or by oxidation of hydrogen chloride.
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What are some of the disadvantages of chlorinating water?
The chlorine could react with organic compounds which form chlorinated hydrocarbons many of which could be cancer causing. Also chlorine gas is very harmful and accidents involving chlorine during the chlorination process could be very serious.
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What is an alkali?
An alkali is a compound that forms hydroxide ions (OH-) when dissolved in water.
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What does a reaction between an acid and a hydroxide give?
It gives a salt and water.
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What does a reaction between an acid and a carbonate give?
It gives carbon dioxide, a salt and water.
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What are alkalis used for?
They are used to make chemicals that allow natural dyes to bind to cloth, they are used to convert fats and oils into soap and they are used to manufacturer glass.
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What are the traditional sources of alkalis?
Burnt wood and stale urine.
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What did the first process for manufacturing an alkali use?
They used limestone (calcium carbonate) and salt (sodium chloride)
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What was the problem with this process?
It created a lot of pollution - large volumes of acidic gas (hydrogen chloride) and a lot of solid waste was produced.
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What is the problem with the solid that is produced as a waste product from that reaction?
The solid slowly released hydrogen sulphide which is a toxic and foul smelling gas.
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Why is it important that toxic chemicals get broken down quickly?
Otherwise they will stay in the environment and they could then end up in waterways and then if an animal drinks the water they become infected and it gets passed up the food chain.
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What happens once an insecticide seeps into a river?
Once it is in the water small plants take up the little insecticide and then small fish tend to eat the plant, gradually the insecticide works it's way up the food chain until it gets to the last animal who will die because of the insecticide.
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How can plasticisers harm the environment?
It is made up of PCBs and this can leach out of the plastic and into water sources . PCBs are toxic so it will result in animals getting killed.
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What is a life cycle assessment?
It is where the manufacturer looks at every stage of the products life to assess the impact it would have on the enviroment.
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What are the four stages that need to be considered when doing a LCA?
Choice of material, manufacture, using the product and product disposal.
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Other cards in this set

Card 2


What are the other layers that are found under the earth's crust/


The mantle, outer core and then inner core. The core is made out of iron and nickel.

Card 3


What provides evidence that the tectonic plates are moving?


Preview of the front of card 3

Card 4


Why are fossils good evidence for finding out what earth used to be like/


Preview of the front of card 4

Card 5


Where do chemical industries tend to get set up?


Preview of the front of card 5
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