C3

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  • Created by: Faith16
  • Created on: 17-04-16 18:24
What are tectonic plates?
The crust and the upper part of the mantle that have been cracked into a number of large pieces
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How fast do the tectonic plates move?
A few cm per year
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What happens when tectonic plates move?
The mantle is exposed so it rises up through the sea floor and solidifies to form a new crust
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What happens when the crust is formed?
It is magnetised by the Earth's magnetic field (changes direction every half million years so rocks are either normal polarity or reversed polarity)
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How can rocks tell you about the environment in which they formed in?
Fossil- how old a rock is as well as conditions it formed in (e.g. fish- underwater). Underwater- contains shells and ripples created by sea or rivers. Sediment- rocks either carried by water or air depending on the shape of grains found in that rock
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What processes create minerals?
Sedimentation, dissolving, evaporation, erosion and mountain building
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How are sedimentary rocks formed?
From layers of sediment (shells, bones or sea creatures or erosion of pre-exsisting rocks) being laid down in lakes or seas and the weight of this squeezes out the water which deposit natural mineral cement that hold the sediment particles together.
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What is erosion?
Natural weathering of large pieces of rock by rain and wind which creates ting particles of sediment
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What is limestone?
A grey/white sedimentary rock that mostly consists of calcium carbonates
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How is coal formed?
Millions of fossilisation of layers of plant matter (mostly consists of carbon). Some types are very hard due to the deposits being under high pressures and temperatures (can happen during mountain building)
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How is salt formed?
Salt is formed when the seas containig dissolved salt evaporate causing it to be buried and compressed under other layers of sediment (rock salt- Cheshire and Teeside)
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What is rock salt?
A mixture of rock and impurities found in underground deposits
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How is rock salt extracted from the ground and what is it normally used for?
It is drilled, blasted and dug out of the grounf and brought to the surface using machinery. Normally used for salt on the roads (lowers freezing point of water to -5 and sand and grit give grip on unmelted ice)
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What is solution mining?
Water is injected into the salt deposit through an outer pipe, dissovles salt to make brine, pressure forces brine to surface through inner pipe, brine stored in wells and pumped to refining plant when needed
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What happens to brine at refining plants?
Impurities are removed and then pumped into containers, brine then boiled to make water evaporate to leave salt. (used for table salt and salts used in chemicals)
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How does salt mining affect the environment?
Land above mines can collapse (subsidence)- can be reduce risk by leaving well-supported caverns, spacing apart and filling them in. Also mining needs alot of energy (pollution)
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How can salt be obtained from the sea?
Seawater flows into shallow pools, left to evaporate in sun, process repeated several times then salt collected (method produces the purest salt)
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What is refined salt used for in the food industry?
To enhance the flavour of foods and as a preservative e.g. dries out meat when added by absorbing water and any bacteria (cured meat)
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What are the health issues with over eating salt?
High blood pressure (strokes and heart attacks) and increase the chance of stomach cancer, osteoporosis and renal failure (mostly in processed foods)
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What are the Department of Health and the Department for Environment, Food and Rural Affairs functions?
Carry out a risk assessment for chemicals in food to make sure they are safe and to advice the public about how food affects their health
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Why do food manufacturers still include a lot of salt in their products?
As it may cost too much to reformulate the recipes, the product might not taste as good or last as long so the sales may decrease
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What is the first thing done to brine in a chemical industry?
Electrolyse it (pass an electric current through it) to cause a chemical change to split the brine into hydrogen, chloride and sodium hydroxide
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What is chlorine used for?
Disinfectants, killing bacteria (swimming pools and domestic water supplies), household bleach, plastics (PVC), hydrochloric acid and insecticides
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What is hydrogen used for?
To make ammonia, change oils into fats for making margarine (hydrogenated vegetable oil) and used as fuel for fuel cells, welding and metal cutting
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What is sodium hydroxide used for?
It is a strong alkali so widely used in chemical industry and in soap, ceramics, organic chemicals, paper pulp, oven cleaner and household bleach
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How is bleach made?
By reacting chorine with sodium hydroxide
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What is the environmental impact of large scale electrolysis?
Needs a lot of energy (burning fossil fuels- pollution and using finite resources), mercury is used which is toxic and asbestos is used (can cause lung cancer)
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What was discovered in 1970 about mercury?
A lot of it was found in a river in Ontario in Canada which contaminated the fish causing the fisheries to close and the people who ate the fish became seriously ill
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Why is chlorine an important part of water treatment?
Kills disease-causing microorganisms, kills off bacteria even after treatment, prevents growth of algae
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What diseases are caused by drinking dirty water?
Cholera, typhoid and dysentery (1.8 million people die each year)
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Why does chlorine have to be separated from compounds such as sodium chloride and hydrogen chloride before used to treat water?
Because the properties of the compounds are different from the properties of the element
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What is the chemical equation for adding oxygen to hydrogen chloride?
4HCl + O ^2 = 2Cl ^2 + 2H ^2 O
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What are the disadvantages of chlorinating water?
Water contains a variety of organic compounds (decomposition of plants) so chlorine can react with these to form chlorinated hydrocarbons which can cause cancer. Also chlorine gas is harmful if breathed in and liquid chlorine causes chemical burns
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What is an alkali?
A compound that forms hydroxide ions when dissolved in water e.g. sodium hydroxide, potassium hydroxide and calcium carbonate
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What is a neutralisation reaction?
When an acid and alkali react together to form salt and water (neutral)
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What are two types of neutralisation reactions?
Reaction between acid and hydroxide gives salt and water. Reaction between acid and carbonate gives carbon dioxide, salt and water.
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How are alkalis used?
Crops need neutral soil to grow, used in chemicals to allow natural dyes to bind to cloth, covert fats and oils into soap, manufacture of glass
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What are traditional sources of alkalis?
Burnt wood and stale urine
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What happened when people first manufactured sodium carbonate?
Used limestone and salt which created a lot of pollution as large volumes of the acidic gas hydrogen chlorine was released into the environment and solid waste was produced which slowly realised hydrogen sulphide which is toxic and foul smelling gas
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What produces can be made using chemistry?
Drugs, chemicals in paint and dyes, chemicals used in industry (acids and alkalis), chemicals at home (bleach and toiletries),agricultural chemicals (fertilisers), plastics, metals and fuels
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How are chemicals dangerous for food chains?
If they are not broken down then they can end up in waterways or eaten by animals which can be spread along a food chain
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Give an example of a chemical affecting a food chain.
Insecticide seeps into river, plants take up little insecticides,small animals eat plants, fish eat small animals, eels eat small fish, otter eats eels
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How do plasticisers harm the environment?
Plasticiser PCB used to make PVC that had more heat and fire resistance for use in electrical wiring but PCB leached out of plastic into water sources poisoning the fish and later on humans who ate the fish
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What does LCA stand for?
Life Cycle Assessment
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What are the different stages of LCA?
Choice of material, manufacture, using the product and product disposal
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Other cards in this set

Card 2

Front

How fast do the tectonic plates move?

Back

A few cm per year

Card 3

Front

What happens when tectonic plates move?

Back

Preview of the front of card 3

Card 4

Front

What happens when the crust is formed?

Back

Preview of the front of card 4

Card 5

Front

How can rocks tell you about the environment in which they formed in?

Back

Preview of the front of card 5
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