C3 Flashcards
Why do geologists study rocks?
to see how the Earth’s surface has changed.
What to geologists look at in rocks?
- how rocks form
- how they change
- when changes happened
How do geological changes happen?
by slow movements of tectonic plates
How do tectonic plates move?
by sliding past eachother, colliding or pulling apart.
What do plate collisions build?
mountain ranges, which errode over time.
What was the positioning of england, wales and scotland 600 million years ago?
England and Wales were separated from Scotland by ocean, and both were near the south pole.
What was Pangea?
a supercontinent which formed gradually when different continents drifted and crashed together.
What is britain made from?
rocks from different ancient continents.
Originally what was Britain nearer to which gave it a warmer climate?
the equator
What is formed as lava solidifies?
igneous rocks
What does the UK have due to conditional movement and climate changes?
many different rocks and raw materials
What do magnetic materials in the lava line up along?
the Earth’s magnetic field.
How can geologists date rocks and track the slow movements of continents?
using changes in magnetic patterns, linked to radioactive decay.
What evidence supports plate tectonic theory?
the slow movement of continens.
What are buried in the Earth’s crust?
Rocks
What are the three most important raw materials?
coal, salt, limestone
When the industrial revolution started, where was coal, salt and limestone found?
- coal in south lancashire
- salt in cheshire
- limestone in the peak district
What was the process of the formation of limestone while Britain was covered by sea?
- shellfish died forming sediments on the sea bed
- sediments compacted and hardened to form linestone, a sedimentary rock.
- tectonic plate movements pushed the rock to the surface
- gradually the rocks above were eroded away until the limestone was exposed.
When did coal first form?
in wet swampy conditions when plants like trees and furns died and became buried.
How did salt form in cheshire?
- Rivers brought dissolved salts into the sea
- Climate warming evaporated the water, leaving salt that mixed with sand blown in the wind.
- Rock salts formed and was buried by other sediments
What evidence have geologists found for limestone, coal and salt formation?
- coal contains fossils of the plants that formed it
- limestone contains bits of shell fragments from sea creatures.
- rock salt contains different-shaped water-eroded grains and wind-eroded grains.
What are the three uses of salts?
- in the food industry
- as a source of chemicals
- to treat icy roads in winter
How can salt be obtained?
- collecting and evaporating sea water
- mining underground deposits of rock salt
Why is rock salt spreaded on icy roads?
- the rock salt is insoluble but the sang in the rock salt gives grip
- it shows up so people know when the roads have been gritted
- the salt in solution lowers the freezing point, preventing ice forming as easily
How much does the cheshire rock salt mine mine a year?
a million tonnes
How can purer salt be obtained?
solution mining
What can mining rock salt and solution mining cause?
subsidence
Why can half the rock salt not be mined?
it is needed to stay in place for support
What is a negative impact of salt mining?
-mining can allow water in mines, which may let salt leach out into water supplies, contaminating them
What is a negative impact of evaporating salt?
-it takes up large areas and spreads salt into the local environment, which damages habitats
Why is salt used in food?
- as flavouring
- as a preservative
What does a higher salt level in food prevent?
bacteria growth
Why are many people worried about salt intake?
-it can cause high blood pressure, heart failure and strokes.
What are the government Department of Health (DH) and the Department of the Enviroment, Food and Rural affairs (Defra) responsible for?
carrying out risk assessment for chemicals in food and advising the public about how food affects health.
What colour does litmus paper turn for alkalis and acids?
acids- red
alkali- blue
Alkalis neutralise acids to make…
salts
What is it called when alkalis neutralise acids to make salts?
neutralisation
What is the word equation for neutralisation?
acid+alkali—>salt and water
What are alkalis used for?
dyeing cloth, neautralising acid soil, making soap and making glass.
What have been used as source of alkali in the past?
stale urine, ash and burnt wood
What does oxidation convert?
hydrogen chloride to chlorine
How can chlorine be made?
by reactivng hydrochloric acid and magnese dioxide
How can pollution problems be solved?
by turning waste into useful chemicals.
Who discovered how to manufacture an alkali and how was it done?
In 1787 Frenchman Nicholas Leblanc invented the Leblanc process which made sodium charbonate by reacting salt and limestone, heated with coal.
-It gave off large amounts of hydrogen chloride, which is a harmful gas and solid waste called galligu.
After the Leblanc process, what was the process later invented to change the harmful hydrogen chloride into useful substances?
- chlorine used to bleach textiles prior to dyeing
- hydrochloric acid, which is a starting material for making other chemicals
Hydroxide+acid—>?
salt+water
carbonate+acid—>?
salt+water+carbon dioxide gas
What is chlorines uses?
added to water supplies to kill microorganisms.
What benefits has chlorination had?
killed water-bourne microorgaisms that cause diseases like cholorea and typhoid.
What possible risk is there of chlorination?
possible development of cancer.
What does electrolysis do?
breaks up compounds using an electric current.
What does the electrolysis of brine make?
chlorine gas, hydrogen gas, sodium hydroxide solution
What is a positive and negative electrode called?
positive-anode
negative- cathode
Why is electrolysis expensive?
large amounts of electricity is needed
What is one method to electrolyse brine continuously?
the membrane cell method
What happens during brine electrolysis?
Chlorine forms at the anode and hydrogen at the cathode.
what are the industrial uses of chlorine, hydrogen and sodium hydroxide?
chlorine- plastics like PVC
hydrogen- making margarine, rocket fuel and fuel cells in vehicles
sodium hydroxide- paper recycling, industrial cleaners and refining aluminium
What is a risk assessment used to find?
how dangerous substances are
What 4 things do we need to know to decide the level of risk?
- how much of it is needed to cause harm
- how much will be used
- the chance of it escaping into the enviroment
- what or who it may effect.
What is PVC?
a plastic containing carbon, hydrogen and chlorine.
What does plasticiser do to PVC?
makes it softer
What is plasticised PVC used for?
to cover electrical wires, for clothing and for seat covers
What would happen if plasticiser molecules leached out of the PVC to the surroundings?
they could have harmful effects
What is released when PVC is burnt?
a toxic gas including dioxins, which are believed to be cancer causing.
What does he LCA(Life Cycle Assessment) measure?
the energy used to make, use and dispose of a substance and its environmental impact.
