c2 chemistry revision


The earths structure

Crust-made of rock - outer layer

the crust is the upper part of the mantle called the lithosphere

lithosphere is made up of tectonic plates

its cold and rigid

mantle-solid section found between the crust and the core 

core-centre of the earth contains iron

inner core-solid but outer core liquid 

Seismic waves can tell us whats below the crust:

inner structures 

seismic waves can study the earths structure/seismic waves can be as a result of earthquakes or manmade explosions 

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Plate tectonics

The earths structure is made up of large plates of rock

they move about 2.5cm every year

if  they meet they can cause volcanoes and earthquakes

Evidence for plate tectonics :

magma rises up through sea floor through breaks in the earths crust

magam hardens and forms new crust

there has been evidence for continets moving apart 

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Volcanic eruptions

Volcanoes are formes by molten rock from the mantle breaks magam is less dense than the crust so rises up 

its magma until the volcanoe erupts it then becomes lava 

Lava can be thick or runny 

runny lava is fairly safe

thick lava an explosive is very dangerous 

volcanic ash creates fertile land great for farming 

igneous rock formed from cooling magma:

molten rosk cools and becomes solid at different speeds 

molten rock creates igneous rock 

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Limestone and marble

both made from calcium carbonate 

they are both types of rock

theyre made from same chemical but not exactly the same 

marble is much harder than limestone 

granite is even harder than marble

limestone can break down when heated called thermal decomposition

when limestone is thermally decomposed it makes calcuim oxide and carbon dioxide 

calcuim carbonate--->calcium oxide+carbon dioxide 

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Construction materials

aliminium and iron are extracted from other ores in rocks 

glass and bricks are made from materials found in the earths crust 

clay and limestone are heated and makes cement

concrete is quick and cheap

reinforced concrete is stronger than normal comcrete 

solid steel rods are inserted they are known as composite materials 

Removing rock from the environment can damage it 

uses land / destroys habitats 

transporting rock causes noise pollution 

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Extracting pure copper

copper is dug out of the ground as a copper ore :

copper ore is rock that contains copper

copper is often chemically joined to oxygen atoms in these ores 

copper can then be purified by electrolysis 

Electrolysis is used to get very pure copper-splitting up with electrcity

needs two solids that will conduct electricity called electrodes 

Reccling copper saves money and resources 

uses less energy

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An alloy is a mixture of a metal and other elements

steel is an alloy of iron and carbon 

steel is harder than iron and also stronger 

Brass bronze and solder and amalgam are also alloys 

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Iron and aluminium

properties of metals are very important 

iron is more dense than alyminium 

more mass in iron 

iron is magnetic but alyminium isnt

malleable --->means easy to hammer into shape 

iron and aliminium are both good electrical conductors 

iron corrodes easily word equation :iron+oxygen+water--->hydrates iron oxide 

Aliminium doesnt corrode when wet 

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acids and bases

the ph scale and indicators tell us how strong acid or alkali are 

on a scales of 0-14 

neutral at ph 7 pure water

universal indicator----->>>>will help you elvaluate its ph value

litmus paper----->>>>>can be shown to use ph value with a dye that will show a sudden colour change above or below a certain ph will estimate the ph of a soloution stays red=acidic/turns blue if alkaline/same colour neutral

Neutralisation acid+base--->salt+water

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Reactions of acids

Different acids bases make different salts 

oxides and metals are bases

they neutralise acids

they will reactt with acids to form a salt and water

Metal carbonates will also neutralise acids 

they produce carbon dioxide same as above 

salt produced 

acid and metals in the base vary 

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fertilisers help make healthy crops

three essential elements are nitrogen phoshporus and pottasium 

without these or not enough they wont grow

fertilisers can generate these elements in plants

fertilisers must dissolve in water before it can be used by the crop 

helps increase number grown in a certain area aka crop yield 

we need to produce more food as a result of the population rise rapidly

increased crop yield helps us to fufil demand

They also have their problems too many fertilisers can pollute our water supplies 

damage to environment can cause eutrophication increased algae growth ect

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preparing fertilisers

amonia can be used to produce fertilisers 

amonia is an alkali that can be neutralised by acids 

salts made are called ammonium salts

salts are then used as fertilisers

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The haber process

Nitrogen and hydrogen needed to make ammonia 

reversable reaction

means nitrogen and hydrogen can react to make amonia and amonia can break down to give nitrogen and hydrogen

nitrogen obtained in the air

hydrogen from natural gas or craking crude oil 

amonia is formed as a gas but turns to liquid as it cools and is removed reaction contains an iron catalyst that speeds it up

industrial conditions:pressure-high/tempreture 450degrees celsius/catalyst iron

Amonia can be used to make fertilisers 

nitric acid used to make explosives and fertilisers 

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SODIUM CHLORIDE=mined from underneath cheshire

underground found in salt deposits 

can be extracetd by mining and solution mining

mining salt is seperated from other materials

solution mining dissolves the salt solution then forced to the surface

Electrolysis of brine gives hydrogen and sodium hydroxide

concerntrated sodium chloride solution aka brine

brine can be electrolysed

they wont react

three useful products include:hydrogen gas chlorine gas sodium hydroxide 

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