C2

Earth’s structure

Thin, rocky crust

Iron core

MantleJust below crust = cold, rigidDeeper down = hot, can move

Tectonic plates = move 2.5cm per year.= millions of years to form continents.Plate tectonics TheoryConvection currents in the mantle = plates move.Oceanic crust less dense than continental crust.Collision between oceanic and continental plates = subduction and meltingPlates cooler at ocean margins so sink

Lithosphere Crust + upper mantleMade of tectonic platesTectonic plates = less dense than mantle float

Problems with studying the Earth’s structureCrust is too thick to drill through.Have to use S and P waves from man-made explosions

The development of the Plate Tectonics theoryWegner came up with continental drift in 1914.Not accepted by scientists – Wegner wasn’t a geologist, it went against their ideas.1960s – sea floor spreading discovered – supported theory.More research supports it. Theory accepted.Plate tectonics is widely accepted It explains lots of evidenceDiscussed and tested by lots of scientists.

Volcanoes – studied to predict eruptions - to find out the Earth’s structure

Better predictions now – better measurement techniques and theories – still not 100%People live there – fertile soilLavaSlow cooling = big crystalsThicker lava = more dangerous eruptionRock Lava Eruption

Iron rich basalt Runny Safe

Silica rich rhyolite Thick Explosive

Construction Materials

Construction Material Made from

Aluminium/Iron Ores

Bricks Clay

Glass Sand

Rocks used in constructionLimestone = soft - sedimentary rock - layersMarble = hard- metamorphic rock - -made by high temperature and pressureGranite = really hard – igneous rock

LimestoneQuarrying destroys the landscape, causes noise, traffic and dust.Thermal decomposition A reaction where heat is used to breakdown one substance into at least two new substances.

calcium carbonate calcium oxide + carbon dioxide CaCO3 CaO + CO2

Cement = limestone and clay heated together.

ConcreteCement + sand + gravel + waterthen let it set.Reinforced ConcreteConcrete + steel Composite material (mixture of two materials = mixture of their properties.)

Reinforced concrete is better than normal concrete.It is as hard as normal concreteSteel makes it more flexible and stronger in tension (when you stretch it).

Advantages of recycling copper Disadvantages of recycling copper

Low melting point – easy to melt down – less energy needed than for mining it.

Getting the public to do it

Cheaper than extracting it from its ore.

Has to be sorted from other metals

Saves copper resources Pure copper must not be mixed with less pure.

AlloysMixtures containing one or more metals elements.

Alloy Made from Use

Amalgam Mercury Tooth fillings

Brass Copper + zinc

Musical instruments, decorations, coins

Solder Lead + tin Join electrical wires

Purification of Copper detailsImpure copper as anode.Pure copper as cathodeCopper sulfate solution as electrolyte

Cathode gains mass as copper is deposited.Cu2+ + 2e- Cu – reduction (RIG)

Anode loses mass as copper dissolves.Cu – 2e- Cu2+ - oxidation (OIL)

Smart AlloysShape memory – can bend, warm up and then it returns to shape.Nitinol – bendy glasses frames – returns to original shape after bending

Metals and Alloys

Extraction of Copper- Extracted from its ore using carbon.- Reduction reaction – because oxygen is

removed from the copper- Then purified by electrolysis

Making Cars

RustingIs an oxidation reaction because oxygen is added to the iron.Iron + oxygen + water hydrated iron (III) oxideRusting happens faster when the water is salty or acidic

Aluminium does not corrode because• A layer of aluminium oxide forms on the surface• Aluminium oxide is strong

AlloysHave properties that are different to the metals they are made from which can make them more usefulSteel is harder and stronger than ironSteel is less likely to corrode than iron.

Car made out of steel

Car made from aluminium

Car will be cheaper

Car body will be lighter so you get better fuel economy.

Car body will corrode less so the car will last longer

Recycling and CarsEU law says 85% of a car should be recyclable.Advantages of recycling car parts1. Saves metal resources because less

has to be mined.2. Saves money and energy3. Less crude oil is used to make plastic

parts4. Glass has been recycled for a long time

so is easy to do.5. Batteries contain toxic material so it is

better that this is not dumped.

DisadvantageAll the different materials need to be separated first.

Iron Aluminium

More dense Less dense

magnetic Not magnetic

corrodes Does not corrode

Malleable

Good electrical conductor

Ammonia

Making AmmoniaAmmonia is made in the Haber processnitrogen + hydrogen ammonia N2 + H2 NH3

Needs:• Nitrogen – from the air• Hydrogen – from natural gas or crude oil• Iron catalyst –increases the rate and does

not affect the % yield• High pressure – higher pressure increases

the % yield of ammonia• Temperature of about 450oC – high

temperature decreases the % yield of ammonia but gives a faster reaction – we choose a compromise temperature for a high rate and quite high yield.

Unreacted nitrogen and hydrogen are recycled.

Costs and IndustryHigh pressure – high cost of equipmentHigh temperature – high energy costCatalyst – reduces cost by increasing rateRecycling the unreacted nitrogen and hydrogen reduces costsAutomation – reduces the wages bill

Rate and % yield = high enough for sufficient daily rate.Low % yield sometimes ok if the starting materials are recycled many times.Optimum conditions = lowest cost (not fastest reaction or highest yield)

UsesAmmonia is used to make fertilisers and nitric acid.

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