GCSE Earth Materials 000

8/14/2019 GCSE Earth Materials 000

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Earth MaterialsEarth Materials


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LimestoneLimestoneLimestone is a __________ rock made up ofmainly calcium carbonate. Its cheap and easy toobtain. Some uses:

1) Building materials limestone can be quarriedand cut into blocks to be used in _______.

However, it is badly affected by ____ ____.2) Glass making glass is made by mixing limestonewith _____ and soda:

3) Cement making limestone can be roasted in a rotary kilnto produce dry cement. Its then mixed with sand and gravelto make _______.

Limestone + sand + soda glass

Words sand, building, sedimentary, concrete, acid rain


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LimestoneLimestoneIf soil is too _____ crops will fail. Limestone can also be usedas a neutralising agent. There are two reactions to know:

1) Firstly, a THERMAL _________________ reaction is usedto break the calcium carbonate down into calcium oxide(quicklime) and _______ __________:

2) This is then slaked with water to produce calciumhydroxide (_________ lime):

Calcium hydroxide is alkaline and is used to ______ acidic soil.

Calcium carbonate calcium oxide + carbon dioxideHEAT

Calcium oxide calcium hydroxideWATER

Words slaked, acidic, neutralise,

decomposition, carbon dioxide


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Formation of oil and gasFormation of oil and gas

1) Layers of

dead sea _____settle on theseabed.

2) Layers of

__________rock build up ontop.

3) The heat and ________ from

these rocks, along with theabsence of ______, mean that oiland gas are formed over ______of years.

Words sedimentary, millions, oxygen, creatures, pressure


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Hydrocarbons and crude oilHydrocarbons and crude oil

Longer chains mean

Less ability to flow

Less flammable

Less volatile

Higher boiling point

Increasing

length

Crude oil is a mixture of HYDROCARBONS

(compounds made up of carbon and hydrogen).Some examples:

Ethane

C C

HH

HHH

H

Butane

C C

HH H

HH

H C C H

H

HH


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Fractional distillationFractional distillationCrude oil can be separated by fractional distillation. The oil is evaporatedand the hydrocarbon chains of different lengths condense at differenttemperatures:

Fractions withlow boiling

points condense

at the top

Fractions withhigh boiling

points condenseat the bottom


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CrackingCrackingShorter chain hydrocarbons are in greater demand becausethey burn easier. They can be made from long chain

hydrocarbons by cracking:

Butane

Ethane

Ethane

For example, this bondcan be cracked to give

two of these:


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AlkanesAlkanesAlkanes are SATURATED HYDROCARBONS. What does thismean?

HYDROCARBONS are molecules that are made up ofhydrogen and carbon atoms

SATURATED means that all of these atoms are held

together by single bonds, for example:

Ethane Butane

Alkanes are fairly unreactive (but they do burn well).


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AlkenesAlkenesAlkenes are different to alkanes; they contain DOUBLECOVALENT bonds. For example:

Ethane Ethene

Butane Butene

This double bond means that alkenes have the potential to joinwith other molecules this make them REACTIVE. We can

test for alkenes because they turn bromine water colourless.

ALKAN

ES

AL

KENES


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Monomers and PolymersMonomers and Polymers

Ethene

Heres ethene again. Ethene is called a

MONOMER because it is just one smallmolecule. We can use ethene to makeplastics

Step 1: Break the double bond

Step 2: Addthe moleculestogether:

This molecule is called POLYETHENE,and the process that made it is called

POLYMERISATION


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Another way of drawing itAnother way of drawing itInstead of circles, lets use letters

Ethene

C CHH

HH

C CHH

HH

Ethene

HC C

H

HH

HC C

H

HH

Poly(e)thene

General formula for addition polymerisation:

C Cn

C Cn

e.g. C Cn

H CH3

HH

C C

n

H CH3

HH


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4 Billion years 3 Billion years 2 Billion years 1 Billion years Present day

Evolution of the Earths AtmosphereEvolution of the Earths AtmosphereVolcanic activityreleases CO2, methane,

ammonia and watervapour into theatmosphere. The watervapour condenses toform oceans.

Some of the oxygen isconverted into ozone.

The ozone layer blocksout harmful ultra-violet

rays which allows for thedevelopment of new life.

Green plants evolve which take in CO2 and

give out oxygen. Carbon from CO2becomes locked up in sedimentary rocks ascarbonates and fossil fuels. Methane andammonia react with the oxygen andnitrogen is released. Nitrogen is also

produced as a result of denitrifyingbacteria on nitrates from decaying plants.

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4 Billion years 3 Billion years 2 Billion years 1 Billion years Present day

Evolution of the Earths AtmosphereEvolution of the Earths AtmosphereCarbon

dioxide

Methane Ammonia Oxygen Nitrogen Others

Present dayatmosphere contains78% nitrogen, 21%oxygen, 1% noblegases and about

0.03% CO2

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Carbon dioxide in the atmosphereCarbon dioxide in the atmosphereThe amount of CO2 in the atmosphere is affected by 3 things:

1) Geological activity moves carbonate rocks deep intothe Earth and they release ______ _______ into theatmosphere during volcanic activity.

2) When fossil fuels are burned the carboncontained in them reacts with _____ to form CO2.

3) Increased CO2 in the atmosphere causes a reaction

between it and _______. These reactions produce two things:INSOLUBLE CARBONATES (which are deposited as ______)and SOLUBLE HYDROGENCARBONATES (which ________ inthe seawater). These reactions do not remove ALL of the newCO2 so the greenhouse effect is still getting _______!

Words oxygen, seawater, carbon dioxide, worse, dissolve, sediment

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The Structure of the EarthThe Structure of the EarthA thin crust -

10-100km thick

A mantle has the

properties of a solidbut it can also flow

A core made of

molten nickel and iron.Outer part is liquid

and inner part is solid

The average density of the Earth is much higher thanthe crust, so the inner core must be very dense

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The CrustThe Crust

Sedimentary rockssettle in layers.The oldest rock isat the bottom.

Layers of sedimentary rock can be examined to discover howthey were formed. They are often found folded or fractured:

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Movement of the LithosphereMovement of the LithosphereThe Earths LITHOSPHERE (i.e. the _______) is splitup into different sections called ________ plates:

These plates are moving apart from each other afew centimetres every _______ due to the

________ currents in the mantle caused by the________ decay of rocks inside the core.

Words radioactive, crust, convection, tectonic, year

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Forming new crustForming new crust

Magma

Earthquakes andvolcanic eruptions canbe common here

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Tectonic theoryTectonic theoryPeople once thought that the oceans and the continents were formed byshrinkage from when the Earth cooled down after being formed.

Alfred Wegener proposed something different. Consider Africa and SouthAmerica:

These continents look

like they fit together.They also have similar

rock patterns and fossilrecords. These two

pieces of evidence led

me to believe thatthere was once a singleland mass. This is myTECTONIC THEORY.

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Forming mountainsForming mountainsThe formation of mountain ranges can be explained bytectonic theory. Consider the Himalayas at the top of India:

This is where

India is now

This is whereIndia was millions

of years ago

The intense heat and pressure from this process causes therocks to change structure into metamorphic rocks.

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The Answer:

2) Scientists discovered 50 years later that the Earth generates massiveamounts of heat through radioactive decay in the core. This heatgenerated convection currents in the mantle causing the crust to move

3) We also now know that the sea floor is spreading outwards from plateboundaries

Tectonic theoryTectonic theoryThe Evidence:

2) Some continents look like they used to fit together

3) Similar rock patterns and fossil records

The Problems:

Wegener couldn't explainhow continental drifthappened so nobodybelieved him

Conclusion scientists now believe Wegeners Tectonic Theory

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f h


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Movements of the crustMovements of the crustWhen the lithosphere(crust) moves three

things can happen:

1) Plates move pasteach other, causingearthquakes

2) Plates move away from eachother a constructive platemargin. The gap is filled with

magma which cools to form basalt.This is called sea floor spreading.

3) Plates move towards each other adestructive plate margin. The lessdense one slides underneath

(subduction) and partially melts. Thiscauses volcanoes and earthquakes.

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Evidence for sea floor spreadingEvidence for sea floor spreadingSince the Earth was formed the north and south poles haveperiodically ________ ____. When tectonic plates moveapart and _____ fills the gap the iron particles in the magmaorientate themselves in line with the Earths ________ field.This means that the rock formed on the sea floor contains amagnetic __________ of the changing field:

These magnetic patterns can be used to prove that sea floorspreading does happen, and at a rate of about 2cm per _____.

Words: impression magma swapped over magnetic year

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GCSE Earth Materials 000