core chemistry revision flash cards produced by mr p scutt

Core Chemistry Revision Flash Cards

Produced by Mr P Scutt

What is the difference between:- element

- compound- molecule- mixture


1.1 Atoms, elements & compoundsThe Periodic table Contains about 100 different types of atomsfound naturally on Earth. The elements have been given chemical symbols that are Internationally recognised.

molecules:A group of atoms bonded together

compound:Two of more different atoms bonded together.

element:A substance that is made up of one kind of atom only.

mixture:Contains more than one substance, but they are not bonded together.

Na = sodium

Cl = chlorine

NaCl = sodium chloride

NaCl

O2 = oxygen molecule

Air contains:

O2 N2 CO2 water vapour, trace gases (e.g. Ar)

What are the sub-atomic particles and where are they found?


How are electrons arranged in an atom?


1.2 Atomic Structure

ProtonNeutron

Electron shell or orbital

Nucleus

Electron

A helium atom

Sub atomic particle Charge Mass

Proton +1 1

Neutron 0 1

Electron -1 0 (almost)

He4

2

Atomic mass (Ar)

Atomic number

Proton number

In an atom the number of protons equal the number of electronsAtoms: Have no charge

1.3 The arrangement of electrons in atoms

Electronic structure for K is: 2,8,8,1

First shell holds up to 2 electronsSecond shell holds up to 8 electrons

Third shell holds up to 8 electrons

Forth shell holds up to 18 electrons

nucleus

Energy levels increase as you move away from the nucleus

potassium

K

Electrons and the periodic table:Elements in the same group have the same number of electrons in its outermost shell, therefore the way they react is similar.

2,1lithium

2,8,1

sodium

2,8,8,1potassium

lithium + water lithium hydroxide + hydrogen

sodium + water sodium hydroxide + hydrogen

potassium + water potassium hydroxide + hydrogen

Balance the equation for:

H2 + O2 H2O


How is calcium carbonate formed and what happens to it when it is

heated?


1.5 Chemical equationsLaw of conservation of mass: States that the whatever mass is present on the reactants side will be present on the products side.

Balanced symbol equation: shows the same number of each type of atom on both

the reactant and product side

Step 1: Write a shopping list of atoms on both reactants and products side.

hydrogen + oxygen water

reactants products

H = 2

O = 2

H = 2

O = 1

H2 + O2 H2O

X


reactants products

H = 2 4

O = 2

H = 2 4

O = 1 2

2H2 + O2 2H2O

XX

X


reactants products

xH = 2

O = 2

H = 2 4

O = 1 2

X

X

Step 2: To balance the number of oxygen atoms on the product side we need to double the number of water molecules

H2 + O2 2H2O

Step 3: To balance the number of hydrogen atoms on the reactants side we need to

double the hydrogen molecules

2.1 Limestone and its uses

calcium carbonate calcium oxide + carbon dioxide CaCO3 CaO + CO2

Thermal decomposition (HEAT BREAKDOWN)

sediment layers built up over millions of years

dead shelled marine organisms

As sediment layers build up on top of the dead marine

organisms water is squeezed out ,it cements together and

limestone is formed

Formation of calcium carbonate

(limestone)

Rotary lime kilnHeats calcium carbonate strongly

to make calcium oxide. Energy costs are high & produces 5% of total CO2 caused by human activity. This contributes to global

warming and climate change.

What is produced when a metal carbonate is heated and how can

you test for the products?


Draw the limestone reaction cycle


2.2 Reactions of carbonates

All metal carbonates decompose, however the more reactive the metal carbonate is the more heat energy is required

Testing for CO2 Lime

water

metal carbonate

HEATcalcium hydroxide + carbon dioxide calcium carbonate + water

(limewater) (insoluble precipitate)

Ca(OH)2 + CO2 CaCO3 + H2O

LimewaterFrom: clear/colourlessTo: white precipitate

metal carbonate + acid salt + water + carbon dioxide

calcium + hydrochloric calcium + water + carbon carbonate acid chloride dioxide

CaCO3 + HCl CaCl2 + H2O + CO2

2.3 The “limestone reaction cycle”

1….

3….

4....

Thermal decomposition

Add waterAdd more

water & filter

Add carbon dioxide

2….

Calcium carbonate

Calcium oxide

Calcium hydroxide

Calcium hydroxide solution (limewater)

CaCO3 (s) CaO(s) + CO2(g)

CaO(s)+ H2O(l) Ca(OH)2(s)Ca(OH)2 (aq)

Ca(OH)2 (aq)+ CO2 (g) CaCO3 (s)+ H2O(l)

If you carry on blowing CO2 through, calcium hydrogen carbonate Ca(HCO3)2 forms; this does dissolve in limewater so

it changes back to clear and colourless

What is the difference between cement and concrete?


Discuss the issues surrounding limestone quarrying.


2.4 Cement and concrete

Problems with lime mortar:

Doesn’t set underwater (stops CO2 reacting) Too little sand = mortar shrinksToo much sand = brittle

Cement: Limestone is heated to form calcium oxide this is then mixed with powdered clay

Lime mortar: Calcium hydroxide mixed withsand & water. This then slowly reacts with CO2 in the air to form calcium carbonate (rock!)

calcium hydroxide + carbon dioxide calcium carbonate + water

Ca(OH)2 + CO2 CaCO3 + H2O

Concrete: Aggregates (crushed stones/gravel)are mixed with water, cement and sand.Resists crushing or squashing forces.Can be strengthened by adding steel rods(reinforced concrete) which resist pulling forces.

C:\Program Files\Chemistry\main.html

2.5 Limestone issuesLimestone Quarrying Usually blasted from the quarry using explosives.Dumped into large lorries to be processed.Much of it is processed nearby into cement.

Developments in concreteConcrete can be reinforced with: glass fibres, Kevlar, polypropene.Mixed with recycled paper = resists cracking, impact and cracking.Using reinforced concrete is cheaper than using steel although Steel is much more stronger (more resistant to snapping).

For quarrying• Local jobs (directly and indirectly)• local economy improves. • Limestone is supplied to industry (added to bread, cosmetics, paper).• Improve road links/by-pass.• Site can be re-beautified and used for leisure activities (lakes). = revenue/jobs after quarry closes.

Against quarrying• Many sites in National Parks.• Areas of habitat are destroyed.• Sites have unique/rare wildlife.• Blasting scares off wildlife (sheep!)• Increased traffic noise & jams.• Increased air pollution from lorries.• Increased risk of road accidents.• Dust lays on crops affecting yield.

Give an example of how electrolysis can be used to extract a

metal.


Give an example of how carbon can be used to extract metal.


3.1 Extracting metalsMost metals in the Earth’s crust are found as compounds, usually as an oxide or a carbonate. If a rock contains a high amount of a metal compound it becomes economical to extract. We call this rock an ore.

Haematite (Fe2O3) iron ore Bauxite (Al2O3) aluminium orePotassium

SodiumCalcium

MagnesiumAluminiumCARBON

ZincIronLead

CopperSilverGold

In

crea

sin

g r

eact

ivit

y

Carbon is more reactive than copper so it displaces it from its oxide

Reduction

Native Found naked, on its own!

Use electric to break down to separate the metal from the oxygen

Copper oxide + carbon copper + carbon dioxide CuO + C Cu + CO2

Electrolysis

Panning for gold!

reductionREDUCING AGENT

3.2 Iron and steelsTo remove iron from its ore(iron(III) oxide) we reduce

it in a blast furnace.

iron oxide + carbon iron + carbon dioxide 2Fe2O3 + 3C 4Fe + 3CO2

reductionREDUCING AGENT

Cast iron: 96% iron + impuritiesMakes it hard but brittle.

If we remove the impurities we get pure iron; although it is easily

shaped its too soft to use.

So we mix it with other elementsto form alloys of steel.

Pure iron: atom layers roll over each other making it easy to shape (malleable).

Elements such as carbon, nickel and chromium, disrupt the uniform pattern, so the atoms don’t roll over each other making it is harder to shape.

The higher the % of other element added the harder it is.

Examples:•Carbon steels•Low alloy steels•High alloy steels•Stainless steel

Does not rust, resists corrosionv. hard, strong

What are the main properties of aluminium and titanium? Why do

these properties mean that the metals have to extracted in

different ways.


Discuss the steps to extract copper.


3.3 Aluminium and titanium

Properties of aluminium:• High electrical & heat conductivity• Ductile (shape into wires)

Aluminium is ALLOYED to improve strength.Used to make: drinks cans, saucepans, cooking foil, aircraft & bike frames.

Aluminium at the surface reacts withoxygen, (in the air) forming a thin layer of aluminium oxide around it. This protects it from further corrosion.

Properties of titanium:• High melting point

Properties of both: >Silvery and shiny >Low density > Strong > Resistant to corrosion

layer of aluminium oxide

aluminium

Titanium is used to make: bike and air frames (low density & strength)Parts of jet engines (maintains its strength even at high temps)

Replacement hip joints (low density, strength and corrosion resistance)

Aluminium is extracted by ELECTROLYSIS. High energy costs to melt & electrolyse the Al ore.

Titanium is extracted by DISPLACEMENT using sodium (it’s more reactive) Na itself needs electrolysing from its ore + time consuming + energy costs

3.4 Extracting copper

Copper is purified using electrolysis

Copper rich ore e.g. chalcocite (Cu2S)

Waste SO2 gas is collected as it causes acid rain.

(environmental reason) It’s recovered to make sulfuric acid for extraction process (1)

(economic reason)

Two main extraction methods are used:1. React with sulfuric acid, to make copper sulfate solution.

Then iron is added to displace the copper from its sulfate.

2. Smelting (roasting): by heating the ore in air it is reduced.

copper sulfate + iron iron sulfate + copper

copper(I) sulfide + oxygen copper + sulfur dioxide

copper ore + sulfuric acid copper sulfate

Anode mud

TOXIC!

+ - XImpure copper Pure

copper

Cu2+ used for electrical

wiring

Discuss uses of different metals.


Discuss the issues surrounding metals and their uses.


3.5 Useful metals

CopperWater pipes (doesn’t react with water, can be bent)Wires (good electrical conductivity)Saucepans (good thermal conductivity, maintains shininess)

An alloy is (usually) a mixture of

metals. This makes the

metal harder.

Properties of transition metals: •Good conductors of heat & electricity•Strong•Bent or hammered into shapes

Transition metals

Copper alloys e.g. Bronze (copper + tin) Brass (copper + zinc) Brass harder than bronze used for making musical instruments.

Aluminium alloysMagnox = used in the building of nuclear power plants e.g. Sizewell A Duralumin = aircraft and bike frames (lightweight, strong)

Gold alloys Red gold (gold + copper) White gold (gold + nickel) Used in jewellery because it is hardwearing, shiny and colourful.

3.6 Metallic issuesOpen cast miningScar the landscapeCreate noise and dustDestroys habitatsLeave heaps of waste rock Phytomining

Plants absorb small quantities of metalions through their roots. Plants are then Burnt (possible production of electricity).If the metal is copper, sulfuric acid is added to make copper sulfate.

It is then reacted with iron in a displacement reaction.Finally electrolysis is used to get pure copper metal.

As rain water drains through exposed rock & slag heaps the groundwater becomes acidic. This then runs into rivers causing damage to the wildlife.

Recycling•Saves energy (& money)•Reduces the need to mine more ore•Conserves the Earth’s resources•Prevents pollution problems associated with extraction of metals from its ore ( see above)

BioleachingBacteria to feed on low concentration of metal ions. A chemical process then forms a leachate.

Iron in steel rusts weakeningit. Even protecting it with paint or grease costs money

What is meant by hydrocarbon and what are the properties of alkanes?


Discuss the process of fractional distillation.


4.1 Fuels from crude oil

Alkanes• Saturated hydrocarbons (contains maximum number of hydrogen atoms possible)• Contain single bonds• Has the general formula

Crude oilA mixture containing many different compoundsHydrocarbon

A compound containing hydrogen and carbon atoms ONLY.

SHORT CHAIN

e.g. methane

butane (C4H10)

H HC

H

H

H CC

H

H H

HH

methane (CH4)

ethane (C2H6)

Cn H2n+2

VOLATILITYTendency to turn

into a gas

BOILING POINT

VOLATILITY

VISCOSITY

FLAMMABILITY

LONG CHAIN

e.g. decane

(C10H22)

VISCOSITYHow easy it flows

FLAMMABILITYHow easy it burns

BOILING POINTTemp at which liquid boils

or gas condenses

4.2 Fractional distillationFractionsHydrocarbons with similar boiling points

kerosine

refinery gasesgasoline(petrol)

dieselresidue

Crude oil vaporised

residue

refinery gases

kerosine

diesel

gasoline(petrol)

bottled gas

SHORT CHAIN

LONG CHAIN

LOW BOILING POINT

HIGH BOILING POINT

Fractional distillation column

car fuel

aircraft fuel

lorry & car fuel

e.g. bitumenmaking roads

& flat roofs

Crude oil is fed in at thebottom as a hot vapour.The temperature in the column decreases as

you reach the top. Gases condense when they reach their boiling

point . So different fractions are collected

as liquids at thedifferent levels.

What happens when hydrocarbons are burnt?


How can the burning of fuels be cleaner?


4.3 Burning fuels (burning hydrocarbons)

Pollution from fuels.• Carbon monoxide is a poisonous gas (RBC pick up CO rather than O2). • Particulates (PM10’s) =Tiny solid particles of unburnt HC’s & carbon (soot) (damage cell lining of lungs & could cause cancer. Soot makes things dirty).• Many hydrocarbon fuels contain sulfur. This reacts with oxygen and when dissolved in water it forms acid rain. (damages forests, acidify lakes & land).• High temperature in the car engine allows nitrogen to react with oxygen to form nitrogen oxides (triggers asthma attacks and causes acid rain).

LimewaterClear/colourless

milky precipitate

Captures gases

FUELpropane

anhydrous cobalt

chloride paper

Blue pink

propane + oxygen water + carbon dioxide C3H8 5O2 4H2O + 3CO2

To pump to suck gases

through

water + carbon dioxide carbon monoxide + carbon

Incomplete combustion

(low O2 supply)propane + oxygen

Complete combustion

(good O2 supply)

ice

4.4 Cleaner fuelsCatalytic converter

carbon monoxide + nitrogen oxides nitrogen + carbon dioxide 2CO + 2NO N2 + 3CO2

Contains expensive precious metalsCatalysts works best at high temps

(so needs time to warm up).

clean gases + CO2

Flue gas desulfurisation

calciumhydroxide

Calcium sulfate

waste gases(sulfur dioxide)

Scrubs SO2 from waste gases then Clean gases arereleased into air.

Global dimming

USESplaster boardsplaster of Paris

Particulates in the upper atmosphere reflect back

sunlight. Rainfall patterns are affected & it even cools

the Earth (masking the effects of global warming).

Global warming

What are the alternatives to fossil fuels?


How can the products of fractional distillation be made more useful?


4.5 Alternative fuels1. They are carbon neutral.2. It burns with a much cleaner flame (compared to fossil fuels).3. It comes from a renewable resource (crops).4. If it is spilled it breaks down faster than normal diesel.5. It produces little sulphur dioxide gas and other pollutants .

hydrogen + oxygen water 2H2 + O2 2H2O

Hydrogen as a fuel:Burns with a clean flame.No pollution so no env- effects

Problems: SAFETY: Hydrogen/oxygen mix is explosive when ignited. Possibility

of gas leaking, or accidents.

STORAGE: Hydrogen as a gas takes up more space than a liquid

Bio

fuels/ B

iod

iesel

Crops are grown to make biofuels requires land = habitat loss Biofuels generate money for the economy, however their will be less food crops = price increases = risk of famine.

How can the products of fractional distillation be made more useful?


Some of the products are long-chained and therefore not very useful. They can be broken into smaller chains using the process of “cracking”.

This is carried out by heating the hydrocarbon to form a vapour. Passing it over a powdered catalyst. (Aluminium oxide)

At 400C

What is the structure of the first two alkenes?


What is the structure of the first four alkanes?


What is the structure of the first four alkenes?


Remember:Alkenes have 1 double bond between two carbon atoms.

http://www.google.co.uk/url?sa=i&rct=j&q=alkenes&source=images&cd=&cad=rja&uact=8&docid=oMIlcRZ4N-ylJM&tbnid=BQ0e9_bgV4K7mM:&ved=0CAUQjRw&url=http%3A%2F%2Frevisescience.co.uk%2F2011%2Fschools%2Fsspp%2Fsc1mhc3.asp&ei=G79YU6OKN5Cu7AbunYHICg&bvm=bv.65397613,d.ZGU&psig=AFQjCNEwrO5t0nLU_tVnmb3fM5W3fAqNDw&ust=1398411406783810

What is the structure of the first four alkenes?


Remember:

MEPB

M – 1 carbonE – 2 carbonsP – 3 carbonsB – 4 carbons

http://www.google.co.uk/url?sa=i&rct=j&q=alkanes&source=images&cd=&cad=rja&uact=8&docid=TM6EPoACAV5IrM&tbnid=N7_U_5Lx0l2i7M:&ved=0CAUQjRw&url=http%3A%2F%2Fwww.educator.com%2Fstarkey&ei=eL9YU7vKBcXY7AbztIHYDg&bvm=bv.65397613,d.ZGU&psig=AFQjCNE1dsTZbAC41ELRonyFM9tJy93Z4Q&ust=1398411500996465

How can you test to see if a material is a alkane or alkene?


How can ethanol be produced?


How can you test to see if a material is a alkane or alkene?


You test for the presence of a double bond in the alkene

By adding to bromine water (orange)This will decolourise the water

How can ethanol be produced?


Ethene + SteamProduces ethanolAs it is hydrated

Ferment sugar using yeastSugar carbon dioxide + ethanol

This happens at a low temperature and so is cheaperSugar is renewable and more can be grown

Although product is not as pure

How are polymers formed?


Where are polymers used?


How are polymers formed?


Alkenes can under go a process called polymerisationThis is where small molecules join up to produce long chains of repeating units, called monomers.

Example:Ethene produces polyethene.

Propene produces polypropene.

Depending on the conditions (temperature and pressure) they were made in, their properties differ. They are cheaper than metals, however crude oil is being used up.

Where are polymers used?


Bags – polyethene – as light and stretchy

Lyrca – elastic properties

Waterproof coatingsDental fillings

Medicine – wound dressings (hydrogel)Biodegradable packaging – cornstarch added to material

Memory foam – beds, pillows,

Where do plant oils come from and how are they used?


Compare saturated and unsaturated fats/oils?


Where do plant oils come from and how are they used?


Fruits and seeds contain oilThese can be extracted and used as fuel

By crushing the seed/fruit in a pressUsing a centrifuge – which is like a large tumble drier and separates the oil from the other solid bits.

Distillation refines the oil by removing water.

Used in foods (high energy content), cooking (high temperatures and flavour), fuels (biodiesel)

Compare saturated and unsaturated fats/oils?


Saturated – no double bondsUnsaturated – contains double bonds

Unsaturated oils can be hydrogenated – where extra hydrogen can be added to it. Process uses Nickel catalyst

At 60CThe product is a solid, high melting points, used from spreads

Margarine is partially hydrogenated – partly solid but still can flow and spread easily.

Saturated fats are bad for you as they increase your cholesterol in your blood.

What is an emulsion and how is it useful?


What is Wegner’s Theory?


What is an emulsion and how is it useful?


Oils don’t dissolve in waterIf you mix with water they make an emulsion (droplets suspended in water)

Emulsions are thicker than oil and water

Examples: Mayonnaise, Ice-Cream,

What is Wegner’s Theory?


He realised that there were similar fossils found on opposite sides of the Atlantic ocean – he asked how.

He proposed that idea that once all the land on Earth was as one – a huge super continent called Pangea. Overtime, the land has been pulled apart.

This is by tectonic plates moving. This can be seen now by the different land masses fitting together like a jigsaw – matching shape, rock types and fossils.

What is the Earth’s structure?


Discuss the role of tectonic plates.


What is the Earth’s structure?


Inner core – solid – under huge pressure from the rock above to cause it to be solid as all the particles are forced together. Iron and Nickel found here to give magnetic properties.

Outer core – Liquid (very hot area where the heat is from the radioactive decay of elements)

Mantle – semi-liquid (where convection current occur to move tectonic plates).

Crust – solid

Discuss the role of tectonic plates.


The crust of the Earth is split into different plates called tectonic plates.

These sit on top of the mantle. As the mantle is semi-liquid, convection currents cause the tectonic plates to move.

At the edge of the plates, where they meet (plate boundary), volcanoes and earthquakes occur. These though can not be predicted as they are random events.

What are the main stages in the evolution of the atmosphere on Earth?


What are the main stages in the evolution of the atmosphere on Earth?


1. Volcanic Earth – very hot, lots of Carbon Dioxide in the air. No water as too hot. 2. Earth cools and oceans begin to form, trapping some carbon dioxide in the water.

3. Plants and algae grow and begin to pollute the atmosphere with oxygen and remove carbon dioxide, by the process of photosynthesis.

4. Carbon is trapped in the formation of sedimentary rocks. 5. Oxygen forms the Ozone layer, a layer in the atmosphere that protects us from harmful rays. 6. Todays atmosphere is mainly Nitrogen 78% and Oxygen, which allows us to live on the Earth.

core chemistry revision flash cards produced by mr p scutt

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