Y10 End of Year Exam TopicsC1 Topics Chp 1- Fundamental Ideas Chp 2- Rocks and Building materials Chp 3- Metals and their uses Chp 4- Crude oil and fuels Chp 5- Products from oil Chp 6- Plant oils Chp 7- Our changing planet !C2 Topics Chp 4- Rates and Energy !C3 Topics Chp 3- Energy Calculations

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CHAPTER 1Fundamental Ideas

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C1 1.1 ATOMS, ELEMENTS & COMPOUNDS• All substances are made of atoms

• Elements are made of only one type of atom

!• Compounds contain more than one type of atom

• Compounds are held together by bonds

• Each element has its own symbol in the periodic table

• Columns are called GROUPS.

• Elements in a group have similar properties

• Rows are called PERIODS

• The red staircase splits metals from non-metals

An atom is made up of a tiny nucleus with electrons around it

C1 1.2 ATOMIC STRUCTURE

• Atoms contain PROTONS, NEUTRONS & ELECTRONS

• Protons and Neutrons are found in the NUCLEUS

• Electrons orbit the nucleus

• ATOMIC NUMBER ! the number of protons in the nucleus ! the periodic table is arranged in this order

!• MASS NUMBER ! the number of protons plus neutrons

!Number of neutrons = Mass Number – Atomic Number

Any atom contains equal numbers of protons and electrons

PARTICLE RELATIVE CHARGE

RELATIVE MASS

Proton +1 (positive) 1

Neutron 0 (neutral) 1

Electron -1 (negative) 0

C1 1.3 ELECTRON ARRANGEMENT

• Electrons are arranged around the nucleus in SHELLS (or energy levels)

• The shell closest to the nucleus has the lowest energy

• Electrons occupy the lowest available energy level

• Atoms with the same number of electrons in the outer shell belong to the same GROUP in the periodic table

!• Number of outer electrons determine the way an element reacts

!• Atoms of the last group (noble gases) have stable arrangements and are unreactive

This is how we draw atoms and their electrons

Low energy shell

High energy shell

Sodium

C1 1.4 FORMING BONDS

• Atoms can react to form compounds in a number of ways:

i) Transferring electrons ! IONIC BONDING

ii) Sharing electrons ! COVALENT BONDING

IONIC BONDING !• When a metal and non-metal react • Metals form positive ions • Non-metals from negative ions • Opposite charges attract • A giant lattice is formed

COVALENT BONDING !• When 2 non-metals bond • Outermost electrons are shared • A pair of shared electrons forms a bond

CHEMICAL FORMULAE !• Tells us the ratio of each element in the compound !

• In ionic compounds the charges must cancel out: !E.g. MgCl2 !We have 2 chloride ions for every magnesium ion

H2 + O2 ! H2O !!!Add a 2 to the products side to make the oxygen balance !

H2 + O2 ! 2H2O !!This has changed the number of hydrogen atoms so we must now adjust the reactant side: !

2H2 + O2 ! 2H2O

C1 1.5 CHEMICAL EQUATIONS

• Chemical equations show the reactants (what we start with) and the products (what we end up with)

• We often use symbol equations to make life easier

!CaCO3 ! CaO + CO2

MAKING EQUATIONS BALANCEEquations MUST balance !We can ONLY add BIG numbers to the front of a substance !We can tell elements within a compound by BIG letters !CaCO3 ! this is a compound made of 3 elements (calcium, carbon and oxygen)

Ca = 1 C = 1 O = 3

Ca = 1 C = 1 O = 3

• This is balanced – same number of each type of atom on both sides of the equation !

• We can check this by counting the number of each type on either side

H = 2 O = 2

H = 2 O = 1

H = 2 O = 2

H = 4 O = 2

CHAPTER 2Rocks and Building materials

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C1 2.1 LIMESTONE & ITS USES

• Limestone is made mainly of Calcium Carbonate

• Calcium carbonate has the chemical formulae CaCO3

• Some types of limestone (e.g. chalk) were formed from the remains of animals and plants that live millions of years ago

USE IN BUILDING We use limestone in many buildings by cutting it into blocks. !Other ways limestone is used: !Cement = powdered limestone + powdered clay !Concrete = Cement + Sand + Water

HEATING LIMESTONE !Breaking down a chemical by heating is called THERMAL DECOMPOSITION !! Calcium ! Calcium + Carbon Carbonate Oxide Dioxide !! CaCO3 ! CaO + CO2

ROTARY LIME KILN This is the furnace used to heat lots of calcium carbonate and turn it into calcium oxide !Calcium oxide is used in the building and agricultural industries

C1 2.2 REACTIONS OF CARBONATES

• Buildings made from limestone suffer from damage by acid rain

• This is because carbonates react with acid to form a salt, water and carbon dioxide

!Calcium + Hydrochloric ! Calcium + Water + Carbon

Carbonate Acid Chloride Dioxide

!CaCO3 + 2HCl ! CaCl2 + H2O + CO2

TESTING FOR CO2 !• We use limewater to test for CO2 !• Limewater turns cloudy !• A precipitate (tiny solid particles) of calcium carbonate forms causing the cloudiness!

HEATING CARBONATES !Metal carbonates decompose on heating to form the metal oxide and carbon dioxide !!

MgCO3 ! MgO + CO2

C1 2.3 THE LIMESTONE REACTION CYCLE• Limestone is used widely as a building material

• We can also use it to make other materials for the construction industry

!Calcium Carbonate + Heat ! Calcium Oxide

Calcium Oxide + Water ! Calcium Hydroxide (Limewater)

Calcium Carbonate

Calcium Oxide

Calcium Hydroxide

Calcium Hydroxide Solution

Step 1: Add Heat !CaCO3 ! CaO + CO2

Step 2: Add a bit of water !CaO + H2O ! Ca(OH)2

Step 3: Add more water & filter !Ca(OH0)2 + H2O ! Ca(OH)2 (aq)

Step 4: Add CO2 !Ca(OH)2 + CO2 ! CaCO3 + H2O

Limestone

C1 2.4 CEMENT & CONCRETE

CEMENT Made by heating limestone with clay in a kiln !MORTAR Made by mixing cement and sand with water !CONCRETE Made by mixing crushed rocks or stones (called aggregate), cement and sand with water

! C1 2.5 LIMESTONE ISSUES

BENEFITS • Provide jobs • Lead to improved roads • Filled in to make fishing lakes or for planting trees

• Can be used as landfill sites when finished with

DRAWBACKS • Destroys habitats • Increased emissions • Noisy & Dusty • Dangerous areas for children • Busier roads • Ugly looking

CHAPTER 3Metals and their uses

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C1 3.1 EXTRACTING METALS

• A metal compound within a rock is called an ORE

• The metal is often combined with oxygen

• Ores are mined from the ground and then purified

!Whether it’s worth extracting a particular metal depends on:

à How easy it is to extract

à How much metal the ore contains

!The reactivity series helps us decide the best way to extract a metal:

!à Metals below carbon in the series can be

reduced by carbon to give the metal element

!à Metals more reactive than carbon cannot be

extracted using carbon. Instead other methods like ELECTROLYSIS must be used

THE REACTIVITY SERIES

C1 3.2 IRON & STEELS

• Iron Ore contains iron combined with oxygen • We use a blast furnace and carbon to extract it (as it’s less reactive than carbon) • Carbon REDUCES the iron oxide;

!Iron (III) Oxide + Carbon ! Iron + Carbon Dioxide

!• Iron from the blast furnace contains impurities:

à Makes it hard and brittle à Can be run into moulds to form cast iron à Used in stoves & man-hole covers

!• Removing all the carbon impurities gives us pure iron

à Soft and easily shaped à Too soft for most uses à Need to combine it with other elements

• A metal mixed with other elements is called an ALLOY

!E.g. Steel ! Iron with carbon and/or other elementsThere are a number of types of steel alloys:

àCarbon steels

à Low-alloy steels

à High-alloy steels

à Stainless steels

C1 3.3 ALUMINIUM & TITANIUM

Aluminium Titanium

Property • Shiny • Light • Low density • Conducts electricity and energy • Malleable – easily shaped • Ductile – drawn into cables and wires

• Strong • Resistant to corrosion • High melting point – so can be used at

high temperatures • Less dense than most metals

Use • Drinks cans • Cooking foil • Saucepans • High-voltage electricity cables • Bicycles • Aeroplanes and space vehicles

• High-performance aircraft • Racing bikes • Jet engines • Parts of nuclear reactors • Replacement hip joints

Extraction

Electrolysis !• Aluminium ore is mined and extracted. • Alumminium oxide (the ore) is melted • Electric current passed through at high temperature •!! Expensive process – need lots of heat and electricity

Displacement & Electrolysis !• Use sodium or potassium to displace

titanium from its ore • Get sodium and magnesium from

electrolysis • !! Expensive – lots of steps involved, &

needs lots of heat and electricity

C1 3.4 EXTRACTING COPPER

COPPER-RICH ORES These contain lots of copper. There are 2 ways to consider:1. Smelting • 80% of copper is produced this way • Heat copper ore strongly in a furnace with air

Copper + Oxygen ! Copper + Sulphur Sulphide Dioxide

!• Then use electrolysis to purify the copper • Expensive as needs lots of heat and electricity

!2. Copper Sulphate • Add sulphuric acid to a copper ore • Produces copper sulphate • Extract copper using electrolysis or displacement

LOW GRADE COPPER ORESThese contain smaller amount of copper. There are 2 main ways:1. Phytomining

• Plants absorb copper ions from low-grade ore

• Plants are burned • Copper ions dissolved by adding sulphuric acid

• Use displacement or electrolysis to extract pure copper 2. Bioleaching

• Bacteria feed on low-grade ore • These produce a waste product that contains copper ions

• Use displacement or electrolysis to extract pure copper

C1 3.5 USEFUL METALS

TRANSITION METALS • Found in the central block of the periodic table

Properties: • Good conductors of electricity and energy • Strong • Malleable – easily bent into shape

Uses: • Buildings • Transport (cars, trains etc) • Heating systems • Electrical wiring

Example: Copper 1. Water pipes – easily bent into shape, strong,

doesn’t react with water 2. Wires – ductile and conduct electricity

COPPER ALLOYS

Bronze – Copper + Tin - Tough - Resistant to corrosion

Brass – Copper + Zinc - Harder but workable

!ALUMINIUM ALLOYS

• Alloyed with a wide range of other elements

• All have very different properties

• E.g. in aircraft or armour plating!

!GOLD ALLOYS

• Usually add Copper to make jewellery last longer

C1 3.6 METALLIC ISSUES

EXPLOITING ORES Mining has many environmental consequences: • Scar the landscape • Noisy & Dusty • Destroy animal habitats • Large heaps of waste rock • Make groundwater acidic • Release gases that cause acid rain

!RECYCLING METALS • Recycling aluminium saves 95% of the energy

normally used to extract it! • This saves money! • Iron and steel are easily recycled. As they are

magnetic they are easily separated • Copper can be recycled too – but it’s trickier as

it’s often alloyed with other elements

BUILDING WITH METALS

Benefits

• Steel is strong for girders

• Aluminium is corrosion resistant

• Many are malleable

• Copper is a good conductor and not reactive

!Drawbacks

• Iron & steel can rust

• Extraction causes pollution

• Metals are more expensive than other materials like concrete

CHAPTER 4Crude oil and fuels

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C1 4.1 FUELS FROM CRUDE OIL

CRUDE OIL • A mixture of lots of different compounds [A mixture is 2 or more elements or compounds that are not chemically bonded together]

!• We separate it into substances with similar boiling points • These are called fractions • This is done in a process called fractional distillation

HYDROCARBONS

Nearly all the compounds in crude oil are hydrocarbons

Most of these are saturated hydrocarbons called alkanes

Methane CH4

Ethane C2H6

Propane C3H8

Butane C4H10

General formula for an alkane is CnH(2n+2)

C1 4.2 FRACTIONAL DISTILLATION

This is the process by which crude oil is separated into fractions

à These are compounds with similar sized chains

à Process relies on the boiling points of these compounds

à The properties a fraction has depend on the size of their hydrocarbon chains

!SHORT CHAINS ARE:

à Very flammable

à Have low boiling points

à Highly volatile (tend to turn into gases)

à Have low viscosity (they flow easily)

!Long chains have the opposite of these!

Crude oil fed in at the bottom

Temperature decreases up the column

Hydrocarbons with smaller chains found nearer the top

C1 4.3 BURNING FUELS

COMPLETE COMBUSTION

Lighter fractions from crude oil make good fuels

They release energy when they are oxidised ! burnt in oxygen: propane + oxygen ! carbon dioxide + water

POLLUTION

Fossil fuels also produce a number of impurities when they are burnt

These have negative effects on the environment

The main pollutants are summarised below

Sulphur Dioxide

• Poisonous gas

• It’s acidic

• Causes acid rain

• Causes engine corrosion

Carbon Monoxide

• Produced when not enough oxygen

• Poisonous gas

• Prevents your blood carrying oxygen around your body

Nitrogen Oxide

• Poisonous

• Trigger asthma attacks

• Can cause acid rain

Particulates

• Tiny solid particles

• Contain carbon and unburnt hydrocarbon

• Carried in the air

• Damage cells in our lungs

• Cause cancer

C1 4.4 CLEANER FUELS

Burning fuels releases pollutants that spread throughout the atmosphere:

CATALYTIC CONVERTERS

• Reduces the carbon monoxide and nitrogen oxide produced

• They are expensive

• They don’t reduce the amount of CO2

GLOBAL DIMMING !• Caused by particulates !• Reflect sunlight back into space !• Not as much light gets through to the Earth !

CARBON MONOXIDE Formed by incomplete combustion

GLOBAL WARMING !• Caused by carbon dioxide !• Causing the average global temperature to increase !

SULPHUR DIOXIDE !• Caused by impurities in the fuel !• Affect asthma sufferers !• Cause acid rain ! damages plants & buildings

Carbon + Nitrogen ! Carbon + Nitrogen Monoxide Oxide Dioxide

C1 4.5 ALTERNATIVE FUELS

These are renewable fuels ! sources of energy that could replace fossil fuels (coal, oil & gas)

BIODIESEL ETHANOL HYDROGEN

+ • Less harmful to animals • Breaks down 5 × quicker • Reduces particulates • Making it produces other useful products •!•‘CO2

create it absorb the same amount of CO

• Easily made by fermenting sugar cane !• Gives off COsugar cane it comes from absorbs COgrowing

• Very clean – no CO

!• Water is the only product

- • Large areas of farmland required • Less food produced ! Famine • Destruction of habitats • Freezes at low temps

• Large areas of farmland required • Less food produced as people use it for fuel instead!

• Hydrogen is explosive

• Takes up a large volume ! storage becomes an issue

CHAPTER 5Products from oil

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C1 5.1 CRACKING HYDROCARBONS

CRACKING ! Breaking down large hydrocarbon chains into smaller, more useful ones

SATURATED OR UNSATURATED? !We can react products with bromine water to test for saturation: !!Positive Test: !Unsaturated + Bromine ! COLOURLESS hydrocarbon Water ! = ALKENES !!!Negative Test: ! Saturated + Bromine ! NO RECTION Hydrocarbon Water (orange) ! = ALKANES

CRACKING PROCESS !1. Heat hydrocarbons to a high temp;

then either: !2. Mix them with steam; OR !3. Pass the over a hot catalyst

EXAMPLE OF CRACKING !Cracking is a thermal decomposition reaction: !!C10H22 C5H12 + C3H6 + C2H4 !!!ALKENES !• These are unsaturated hydrocarbons • They contain a double bond • Have the general formula ! CnH2n !

Decane Pentane Propene Ethene

800oC

C1 5.2 POLYMERS FROM ALKENES

PLASTICS ! Are made from lots of monomers joined together to make a polymer

HOW DO MONOMERS JOIN TOGETHER? !!!!!• Double bond between carbons ‘opens up’ • Replaced by single bonds as thousands of monomers join up • It is called POLYMERISATION

MONOMERS POLYMER

EthenePoly(ethene)

nSimplified way of writing it:

‘n’ represent a large repeating number

C1 5.3 NEW & USEFUL POLYMERS

DESIGNER POLYMER ! Polymer made to do a specific job

Examples of uses for them:

• Dental fillings

• Linings for false teeth

• Packaging material

• Implants that release drugs slowly

Light-Sensitive Plasters !• Top layer of plaster peeled

back • Lower layer now exposed

to light • Adhesive loses stickiness • Peels easily off the skin

SMART POLYMERS ! Have their properties changed by light, temperature or other changes in their surroundings

Hydrogels !• Have cross-linking chains • Makes a matrix that traps

water • Act as wound dressings • Let body heal in moist,

sterile conditions • Good for burns

Shape memory polymers !• Wound is stitched loosely • Temperature of the body

makes the thread tighten • Closes the wound up with

the right amount of force

C1 5.4 PLASTIC WASTE

NON-BIODEGRADABLE

• Don’t break down

• Litter the streets and shores

• Harm wildlife

RECYCLING

• Sort plastics into different types

• Melted down and made into new products

• Saves energy and resources…BUT

• Hard to transport and

• Need to be sorted into specific types

!DISADVANTAGES OF BIODEGRADABLE PLASTICS

• Farmers sell crops like corn to make plastics

• Demand for food goes up

• Food prices go up ! less can afford it ! STARVATION

• Animal habitats destroyed to make new farmland

• Unsightly !• Last 100’s of years !• Fill up landfill sites

BIODEGRADABLE PLASTICS !• Plastics that break down easily

• Granules of cornstarch are built into the plastic !

• Microorganisms in soil feed on cornstarch !

• This breaks the plastic down

C1 5.5 ETHANOL

There are 2 main ways to make ethanol

2) ETHENE !Hydration reaction ! water is added !

Ethene + Steam ! Ethanol !C2H4 + H2O ! C2H5OH !

+ Continuous process – lots made! + Produces no waste products !- Requires lots of heat and energy - Relies on a non-renewable resource

1) FERMENTATION !Sugar from plants is broken down by enzymes in yeast !Sugar + Yeast ! Ethanol + Carbon Dioxide !80% of ethanol is made this way !+ Uses renewable resources !-Takes longer to produce - CO2 is given off

A molecule of ethanol

HH-C-C-OH

H

H

H

USES FOR ETHANOL

• Alcohol

• Perfume

• Rocket Fuel

• Solvents

• Antiseptic wipes

C1 6.1 EXTRACTING VEGETABLE OIL

There are 2 ways to extract vegetable oils from plants:

2) DISTILLATION !1. Plants are put into water and boiled 2. Oil and water evaporate together 3. Oil is collected by condensing (cooling

the gas vapours) !Lavender oil is one oil extracted this way

1) PRESSING !1. Farmers collect seeds from plants 2. Seeds are crushed and pressed 3. This extracts oil from them 4. Impurities are removed 5. Oil is processed to make it into a

useful product

FOOD AND FUEL !Vegetable oils are important foods: !• Provide important nutrients (e.g. vitamin E) !• Contain lots of energy ! so can also be used

as fuels !• Unsaturated oils contain double bonds (C=C)

! they decolourise Bromine water

Food Energy (kJ)

Veg Oil 3900

Sugar 1700

Meat 1100

Table for info only – don’t memorise it!

CHAPTER 6Plant Oils

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C1 6.2 COOKING WITH VEGETABLE OILSCOOKING IN OIL !

• Food cooks quicker • Outside becomes crispier • Inside becomes softer • Food absorbs some of the oil • Higher energy content • Too much is unhealthy

HARDENING VEGETABLE OILS !• Reacting vegetable oils with HYDROGEN

hardens them ! increases melting points !• Makes them solid at room temperature !

makes them into spreads! !• Double bonds converted to single bonds

C=C ! C-C !• Now called a HYDROGENATED OIL !• Reaction occurs at 60oC with a nickel catalyst

+

60oC + Nickel catalyst

Double bonds converted to single bonds

Margarine

C1 6.3 EVERYDAY EMULSIONS

Oils do not dissolve in water

Emulsion ! Where oil and water are dispersed (spread out) in each other

! These often have special properties

EMULSION EXAMPLES !1. Mayonnaise 2. Milk 3. Ice cream 4. Cosmetics – face cream, lipstick etc 5. Paint

EMULSIFIERS !• Stop water and oil separating out into

layers !• Emulsifiers have 2 parts that make

them work: !1.Hydrophobic tail – is attracted

to oil !2.Hydrophilic head – is attracted

to water. It has a negative charge !!!

Oil droplet

Emulsifier molecule

Water

-

C1 6.4 FOOD ISSUES

E NUMBER !Additives approved for use in Europe !!EMULSIFIERS !• Improve texture and taste of foods

containing fats and oils !• Makes them more palatable (tasty) and

tempting to eat!

FOOD ADDITIVES !Substance added to food to: !• Preserve it • Improve its taste • Improve its texture • Improve its appearance

VEG OILS !Unsaturated Fats: !• Source of nutrients like vitamin E • Keep arteries clear • Reduce heart disease • Lower cholesterol levels !ANIMAL FATS !Saturated Fats: !• Are not good for us • Increase risk of heart disease • Increase cholesterol

E.g. chocolate!

CHAPTER 7Our changing planet

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C1 7.1 STRUCTURE OF THE EARTH

Atmosphere:

Most lies within 10km of the surface

Rest is within 100km but it’s hard to judge!

Crust:

Solid

6km beneath oceans

35km beneath land

Core:

Made of nickel and iron

Outer core is liquid

Inner core is solid

Radius is 3500km

Mantle

Behaves like a solid

Can flow very slowly

Is about 3000km deep!

C1 7.2 THE RESTLESS EARTH

MOVING CONTINENTS !The Earth’s crust and upper mantle are cracked into a number of pieces ! TECTONIC PLATES !These are constantly moving - just very slowly !Motion is caused by CONVECTION CURRENTS in the mantle, due to radioactive decay !!PANGAEA !If you look at the continents they roughly fit together !Scientists think they were once one large land mass called pangaea, which then broke off into smaller chunks

PLATE BOUNDARIES !Earthquakes and volcanoes happen when tectonic plates meet !These are very difficult to predict

C1 7.3 THE EARTH’S ATMOSPHERE IN THE PAST

PHASE 1:Volcanoes = Steam & CO2

• Volcanoes kept erupting giving out Steam and CO2 !

• The early atmosphere was nearly all CO2 !

• The earth cooled and water vapour condensed to form the oceans

Like this for a billion years!

PHASE 2:Green Plants, Bacteria &

Algae = Oxygen• Green plants, bacteria

and algae ran riot in the oceans! !

• Green plants steadily converted CO2 into O2 by the process of photosynthesis !

• Nitrogen released by denitrifying bacteria !

• Plants colonise the land. Oxygen levels steadily increase

PHASE 3:Ozone Layer = Animals

& Us

• The build up of O2 killed off early organisms - allowing evolution of complex organisms !

• The O2 created the Ozone layer (O3) which blocks harmful UV rays from the sun !

• Virtually no CO2 left

C1 7.4 LIFE ON EARTH

No one can be sure how life on Earth first started. There are many different theories: !

MILLER-UREY EXPERIMENT !• Compounds for life on Earth came from

reactions involving hydrocarbons (e.g. methane) and ammonia !

• The energy for this could have been provided by lightning !!!

OTHER THEORIES !1. Molecules for life (amino acids) came on

meteorites from out of space !2. Actual living organisms themselves arrived on

meteorites !3. Biological molecules were released from deep

ocean vents

The experiment completed by Miller and Urey

C1 7.5 GASES IN THE ATMOSPHERE

THE ATMOSPHERE TODAY: !!!!!!!!!!!!!!!!!The main gases in the atmosphere today are: !1. Nitrogen ! 78% 2. Oxygen ! 21% 3. Argon ! 0.9% 4. Carbon Dioxide ! 0.04%

CARBON DIOXIDE: !• Taken in by plants during photosynthesis !• When plants and animals die carbon is transferred to rocks !

• Some forms fossil fuels which are released into the atmosphere when burnt

The main gases in air can be separated out by fractional distillation. These gases are useful in industry

C1 7.6 CARBON DIOXIDE IN THE ATMOSPHEREThe stages in the cycle are shown below: Carbon moves into and out of

the atmosphere due to !• Plants – photosynthesis & decay !

• Animals – respiration & decay !

• Oceans – store CO2 !• Rocks – store CO2 and release it when burnt

CO2 LEVELS Have increased in the atmosphere recently largely due to the amount of fossil fuels we now burn

CHAPTER 4Rates and energy

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For a reaction to take place: !1. Particles must collide ! but not all

collisions lead to reactions...we need... !

2. Enough energy activation energy !

Activation energy = smallest amount of energy required for a reaction to occur

Rates of reaction

The 4 main factors affecting the rate are: ➢Temperature ➢Concentration or Pressure ➢Surface Area ➢Catalysts

These can either: •Increase chance of a collision •Increase the activation energy

Rates of reaction

Temperature !↑ temperature ↑ kinetic energy in the particles ↑ collisions ↑ successful collisions

Increase in temperature

Rates of reaction

Concentration/Pressure !↑ concentration/pressure ↑ collisions ↑ successful collisions !

Increase in concentration

Rates of reaction

Inside of a large lump is not in contact with other reactants ! it can’t react !Smaller chips have more surface in contact

Surface area ↑ surface area ↑ more surface available for ↑ collisions ↑ successful collisions

Rates of reaction

Catalyst !↓ activation energy Same number of collisions But ↑ successful collisions !Catalysts are usually very expensive But they can be reused

Rates of reaction

CHAPTER 3Energy Calcualtions

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Energy from fuelsAcids

& Alkalis

Calorimeter

Think HSW!

Bomb calorimeter

4.2J raises temp of 1 g of water by

1 degree

Food high in carbs and fats have lots of energy!! ! more than body needs ! obesity

A + B ! C If 0.1 mole of reactants. Total mass of A and B is 100g. Temp start is 19.6, temp max is 26.1 Work out diff….6.5 !!

(Don’t need to learn this, you would get this) So for 0.1 moles = 2730J

For 1 mole 2730 x 10 27300J (27.3kJ) …..exothermic reaction ( as temp rise) = -27.3kJ/

mol

Energy change = mass x 4.2 x temp change

Energy changesAcids

& Alkalis

Reaction = bond breaking ( endo) and bond making ( exo)

EXOTHERMIC !Energy required to break

bonds in less than energy released when new bonds are formed

ENDOTHERMIC !

Energy required to break bonds in greater than energy released when new bonds are formed

CATALYST…. Lowers activation

energy

∆H = - ve ∆H = + ve

Bond energiesAcids

& Alkalis

CH4(g) + 2O2(g) ! 2H2O(l) + CO2(g)

Identify the bonds…..stick diagrams!

Bond Bond energy kJ/mol

H-H 436

Cl-Cl 242

H-Cl 431

O-H 464

C-C 347

C-O 335

O=O 498

∆H = bond breaking + (- bond making)

Add up on the bonds in the reactants. This is bond energy needed to break the bonds

Add up on the bonds in the products. This is bond energy needed to make new bonds.

REMEMBER… making new bonds is an exothermic reaction…so it is always a –ve number