c2 chemistry revision
- Created by: Eleanor200101
- Created on: 21-02-17 18:48
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
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
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
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
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
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
Alloys
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
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
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
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
Fertilisers
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
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
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
SALT
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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