GCSE Chemistry OCR C3 Chemicals in our lives- risks and benefits

annaryann's version from 2016-05-18 18:59


Question Answer
Why do geologiists study rocks?To see how the Earth's surface has changed
What do geologists look at when studying rocks?How they form, how they change, and when changes happened
How do geological changes happen?By slow movements of tectonic plates
What do plate collisions build?Mountain ranges which erode over time
When are igneous rocks formed?As volcanic lava solidifies
What happens in the Earth's magnetic field?Magnetic materials in the lava line up along it
How can geologists date rocks and track the slow movement of continents?Using changes in magnetic patterns
What are three important raw materials?Coal, salt and limestone
Where are the important raw materials found?In the Earth's crust
When were England and Wales separated from Scotland by the ocean?600 million years ago
What is Britain made from?rocks from different ancient continents
When did the industrial revolution start?200 years ago
When did limestone form?While Britain was covered by the sea
How did limestone form?Shellfish died forming sediments on the sea bed, sediments compacted and hardened to form limestone, tectonic plates movements pushed rock to surface, rocks above gradually eroded until limestone was exposed
What type of rock is limestone?sedimentary
What conditions did coal form in?wet and swampy- when plants died and became buried
When was salt formed?while Cheshire was covered by a shallow sea
How was salt formed?Rivers brought dissolved salts into the sea, climate warming evaporated the water leaving salt that mixed with sand blown in by the wind, rock salt formed and was buried by other sediments
What have geologists found evidence for?Limestone, coal and salt formation
What does coal contain?Fossils of the plants that formed it
What does limestone contain?Bits of shell fragments from sea creatures
What does rock salt contain?Different- shaped water- eroded grains and wind- eroded grains
What do ripple marks in rocks indicate?Water flow from rivers or waves in the sea
How can salt be obtained?Collecting and evaporating sea water, mining underground deposits of rock salt
What is the formula for salt?NaCl
Why is rock spread on icy roads?Sand in rock salt gives grip, salt in solution lowers freezing point preventing ice forming as easily
Where is salt extraction from sea water economical?Hot climates
How can purer salt be obtained?Solution mining which is mainly automatic
What can mining rock salt and solution mining cause?Subsidence- about half the rock salt cant be mined as it is left in place for support
What is the effect from evaporating salt from sea water?It takes up large areas and spreads salt into the environment damaging habitats
What does a higher level salt prevent?bacteria growth
What can salt intake cause?High blood pressure, heart failure and strokes
What do alkalis do to indicators?Make them change colour- litmus turns blue in alkalis and red in acids
What is neutralisation?When alkalis neutralise acids to make salts
What is the word equation for neutralisation?acid + alkal ----> salt + water
What are alkalis uaed for?dyeing cloth, neutralising acid soil, making soap, making glass
What are past sources of alkalis?Stale urine and ash from burnt wood
In coastal areas, what could be used to neutralise acidic soils?Seaweed or seaweed ash
How was lime manufactured?By heating limestone (calcium carbonate) in a lime kiln, using coal as fuel
How was alum purified?By reacting it with ammonia contained in stale urine
What did the Leblanc process do?Made sodium carbonate by reacting salt and limestone, heated with coal
What did the Leblanc process give off?large amounts of hydrogen chloride
What did the Leblanc process produce?heaps of solid waste that slowly released toxic hydrogen sulphide
How can chlorine be made?by reacting hyrdrochloric acid and manganese dioxide
What does oxidation convey hydrogen chloride to?chlorine
What colour does an alkali turn a pH indicator?blue or violet
What are alkalis?soluble metal hydroxides and soluble metal carbonates
Why is chlorine added to water supplies?to kill micro organisms
How can chlorine affect human health?it is toxic and dangerous if too much is present in water
How does electrolysis break up compounds?by using an electric current
What does the electrolysis of brine make?chlorine gas, hydrogen gas, sodium hydroxide solution
What does electrolysis cause?a chemical change, making new products
What can chemicals do that are in the form of solids, liquids and gases?spread out into the environment
What is PVC?it is a plastic containing carbon, hydrogen and chlorine
What are plasticisers?small molecules that are added to PVC to make it softer
What is plasticised PVC used for?to cover electrical wires, for clothing and for seat covers
Why can plasticiser molecules be dangerous?they can leach out of PVC into the surroundings
What is the problem with chemicals used for plasticisers?they could have long term effects and large amounts have harmed animals
What happens if PVC is burnt?it gives off toxic gases including doixins
What happens if PVC is eaten?chemicals build up in fat and are thought to cause cancer
What does a life cycle assessment do? Measures the energy used to make, use and dispose of a substance, and it's environmental impact

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