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Chemistry Unit C1 – Chemistry Unit C1 – Chemistry in our WorldChemistry in our World

EdExcel

N Smith

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ElementsElementsIf a solid, liquid or gas is made up of only one type of atom we say it is an element. For example, consider a tripod made up of iron:

These atoms are ALL iron – there’s nothing else in

here

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CompoundsCompoundsCompounds are different to elements. They contain different atoms. Here are some examples:

Glucose

Methane

Sodium chloride (salt)

21/04/2321/04/23Some simple Some simple compounds…compounds…

Methane, CH4 Water, H2O

Carbon dioxide, CO2

Ethyne, C2H2Sulphuric

acid, H2SO4

Key

Hydrogen

Oxygen

Carbon

Sulphur

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Balancing equationsBalancing equationsConsider the following reaction:

Na

O

H HH H

Na

OH

Sodium + water sodium hydroxide + hydrogen

+ +

This equation doesn’t balance – there are 2 hydrogen atoms on the left hand side (the “reactants” and 3 on the right hand side (the “products”)

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Balancing equationsBalancing equationsWe need to balance the equation:

Na

O

H H

H H

Na

OH

Sodium + water sodium hydroxide + hydrogen

+ +

Na

O

H HNa

OH

Now the equation is balanced, and we can write it as:

2Na(s) + 2H2O(l) 2NaOH(aq) + H2(g)

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Some examplesSome examples

Mg + O2

Zn + HCl

Fe + Cl2

NaOH + HCl

CH4 + O2

Ca + H2O

NaOH + H2SO4

CH3OH + O2

MgO

ZnCl2 + H2

FeCl3

NaCl + H2O

CO2 + H2O

Ca(OH)2 + H2

Na2SO4 + H2O

CO2 + H2O

2

2

2 3

2

2

2

2 3

2

2

2

2

2 4

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Hazard signs to learn…Hazard signs to learn…

h i

Acid

Harmful Irritant

Corrosive

Oxidising

Toxic

21/04/23Topic 1 – The Earth’s Sea and Topic 1 – The Earth’s Sea and AtmosphereAtmosphere

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The EarthThe Earth’’s Atmospheres Atmosphere

Carbon dioxide, water vapour

Oxygen Nitrogen Noble gases

For the last 200 million years the atmosphere has remained roughly the same – it contains 78% nitrogen, 21% oxygen, 1% noble gases and about 0.03% CO2

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

Evolution of the EarthEvolution of the Earth’’s s AtmosphereAtmosphere

Carbondioxide

Methane Ammonia Oxygen Nitrogen Others

Present day atmosphere contains 78% nitrogen, 21% oxygen, 1% noble gases and about 0.03% CO2

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

Evolution of the EarthEvolution of the Earth’’s s AtmosphereAtmosphere

Volcanic activity releases CO2, methane, ammonia and water vapour into the atmosphere. The water vapour condenses to form oceans.

Some of the oxygen is converted into ozone. The ozone layer blocks out harmful ultra-violet rays which allows for the development of new life.

Green plants evolve which take in CO2 and give out oxygen by photosynthesis, increasing the amount of oxygen in the atmosphere. Carbon from CO2 becomes locked up in sedimentary rocks as carbonates and fossil fuels and is dissolved into the sea. Methane and ammonia react with the oxygen and nitrogen is released.

21/04/2321/04/23Carbon dioxide in the Carbon dioxide in the atmosphereatmosphereThe amount of CO2 in the atmosphere is affected by 3

things: 1) Geological activity moves carbonate rocks deep into the Earth and they release ______ _______ into the atmosphere during volcanic activity.

2) Human activity - When fossil fuels are burned the carbon contained in them reacts with _____ to form CO2. Furthermore, deforestation means that less _____ are around to take in CO2.

3) Increased CO2 in the atmosphere causes a reaction between it and _______. These reactions do not remove ALL of the new CO2 so the greenhouse effect is still getting _______!

Words – oxygen, seawater, carbon dioxide, worse, trees

21/04/23Topic 2 – Materials from the Topic 2 – Materials from the EarthEarth

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21/04/23What are rocks?

Rocks are made from a combination of minerals and can be hard or soft depending on how the minerals are arranged.

Rocks can be found here…

…and here…

…and here…

…and here

21/04/23Sedimentary rocks

Sandstone

Conglomerate

Limestone

Chalk

21/04/23Sedimentary rocks

How sedimentary rocks are formed:

1) Weathering

2) Transportation

4) Burial

3) Deposition

21/04/23Metamorphic rocks

Slate

Marble (made from chalk or limestone)

Quartzite

21/04/23Metamorphic rocks

Metamorphic rocks are formed by the combined effect of heat and pressure on other rocks:

Pressure from rocks above…

…and heat from magma nearby

21/04/23Igneous rocks

Granite

Pumice

Obsidian

21/04/23Igneous Rock

Granite – a slow cooling rock with big crystals and rich in silica

Basalt – a fast cooling rock with small crystals and rich in iron

Rhyolite – a fast cooling rock with small crystals and rich in silica

Gabbro – a slow cooling rock with big crystals and rich in iron

21/04/23Igneous rocks

Igneous rocks are formed when lava or magma cools down and solidifies

If the lava or magma cools QUICKLY it has SMALL crystals

If the lava or magma cools SLOWLY it has BIG crystals

21/04/23Summary

Sedimentary, igneous or metamorphic?

How they were formed Appearance

Sedimentary

(e.g. sandstone, _______, chalk)

Small pieces of sediment were ______ together by salt and pressure from rocks above

Usually soft, can contain ________, easily eroded

Igneous

(e.g. basalt, _______)

Liquid rock (______ or lava) cooled down and turned back into a ______

Contain ______, very hard, never contain fossils

Metamorphic

(e.g. ______, slate)

Other rocks were acted on by heat and _______ over a long time

Sometimes have tiny crystals, no fossils, always hard and sometimes arranged in _______

Words to use – layers, stuck, granite, marble, fossils, limestone, crystals, pressure, magma, solid

21/04/2321/04/23Conservation of mass in Conservation of mass in reactionsreactions

In any reaction the total mass of products is the same as the total mass of the reactants

Example 1 – Magnesium oxide and hydrochloric acid

Mg OH Cl

Mg ClCl

HH OH Cl

1 x magnesium, 1 x oxygen, 2 x hydrogen and 2 x chlorine atoms

Also 1 x magnesium, 1 x oxygen, 2 x hydrogen and 2 x chlorine atoms

C

H

H

H

HO

O

OO

OH H

OH H

CO

O

Example 2 – Burning methane

21/04/23Calcium Carbonate

Calcium carbonate is a common chemical in the Earth and we’ve already come across it in a number of forms:

ChalkLimestone

Marble (made from chalk or limestone)

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LimestoneLimestone

View video of limestone being quarried

21/04/23Limestone

Limestone is a __________ rock made up of mainly calcium carbonate. It’s cheap and easy to obtain. Some uses:

1) Building materials – limestone can be quarried and cut into blocks to be used in _______. However, it is badly affected by ____ ____.2) Glass making – glass is made by mixing limestone with _____ and soda:

3) Cement making – limestone can be “roasted” in a rotary kiln to produce dry cement. It’s then mixed with sand and gravel to make _______.

Limestone + sand + soda glass

Words – sand, building, sedimentary, concrete, acid rain

21/04/23Pros and Cons of quarrying limestone

Reasons why quarrying limestone is a good idea

Reasons why quarrying limestone is a bad idea

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LimestoneLimestoneLimestone has a number of uses when it undergoes chemical reactions. There are two reactions to know:

1) Firstly, a THERMAL _________________ reaction is used to break the calcium carbonate down into calcium ______ and _______ __________:

2) _____ is then added to produce calcium __________:

Calcium carbonate calcium oxide + carbon dioxideHEAT

Calcium oxide calcium hydroxideWATER

Words – hydroxide, decomposition, carbon dioxide, water, oxide

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The The ““Limestone CycleLimestone Cycle””

Calcium Carbonate

(limestone)

Calcium Oxide

Calcium Hydroxide

Step 1: heat

Step 2: add a little water

Step 3: add more water and filter

Step 4: add CO2

CO2

CO2

Calcium Hydroxide solution

21/04/23Uses of these Calcium compounds

Calcium carbonate (limestone), calcium oxide and calcium hydroxide have a number of uses:

1) Neutralising acidic soil – calcium carbonate, calcium hydroxide and calcium oxide are _______ and can be used to ________ soil acidity to help ______ growth.

2) Removing pollutants – calcium carbonate can be used as a “_______” to remove acidic gases from a coal-fired power station’s waste products, helping prevent ____ _____.

Words – acid rain, alkaline, plant, scrubber, neutralise

21/04/2321/04/23Thermal decomposition of Thermal decomposition of carbonatescarbonates

Limestone undergoes thermal decomposition when heated. The same happens to other carbonates. For example, consider copper carbonate:

Limewater

Copper carbonate (green) turns into copper oxide (black)Limewater goes cloudy due to carbon dioxide being made

Copper carbonate copper oxide + carbon dioxide

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Topic 3 – AcidsTopic 3 – Acids21/04/23

21/04/23Neutralisation reactionsWhen acids and alkalis react together they will NEUTRALISE each other:

OH

Sodium hydroxide

ClH

Hydrochloric acid

The sodium replaces the hydrogen from HCl

ClNa

Sodium chloride

H2O

Water

Na

21/04/23Neutralisation experiment

In this experiment we mixed sodium hydroxide (an _____) and hydrochloric acid together and they ________ each other. The equation for this reaction is…

Sodium hydroxide + hydrochloric acid sodium chloride + water

Words – nitrate, neutralised, alkali, sulphate, salt, evaporating

A ____ was formed during the reaction, and we could have separated this by __________ the solution. The salt that we formed depended on the acid:

• Hydrochloric acid will make a CHLORIDE• Nitric acid will make a _________• Sulphuric acid will make a _________

21/04/23Stomach Acid

Words – digestion, indigestion, acid, alkalis, bacteria

Hydrochloric acid is used in the stomach to help _______ and to kill ______. If we eat too many “rich” foods our stomachs create too much ____ – this is called ______. This acid needs to be neutralised by taking indigestion tablets. Indigestion tablets contain substances such as _______ that neutralise excess stomach acid.

21/04/23Neutralisation reactions

A neutralisation reaction occurs when an acid reacts with an alkali. An alkali is a metal oxide or metal hydroxide dissolved in water.

ACID + ALKALI SALT + WATER

NaClH

H OH ClNa O

H

Copy and complete the following reactions:

1) Sodium hydroxide + hydrochloric acid

2) Calcium hydroxide + hydrochloric acid

3) Sodium hydroxide + sulphuric acid

4) Magnesium hydroxide + sulphuric acid

21/04/23Making salts

Whenever an acid and alkali neutralise each other we are left with a salt, like a chloride or a sulphate. Complete the following table:

Hydrochloric acid

Sulphuric acid

Nitric acid

Sodium hydroxide

Sodium chloride + water

Potassium hydroxide

Potassium sulphate + water

Calcium hydroxide

Calcium nitrate + water

21/04/23Using different bases

A metal oxide base:

Suphuric acid + copper oxide copper sulphate + water

heat

H2SO4(aq) + CuO(s) CuSO4(s) + H2O(l)heat

Sulphuric acid + calcium carbonate calcium sulphate + water + CO2

heat

H2SO4(aq) + CaCO3(s) CaSO4(aq) + + H20(l) + CO2(g)heat

A metal carbonate base:

Acid + metal oxide natural salt solution + water

Acid + metal carbonate natural salt soln + water + CO2

21/04/23Reactions of metals carbonates with acid

A metal carbonate is a compound containing a metal, carbon and oxygen.

METAL CARBONATE + ACID SALT + CARBON DIOXIDE + WATER

Copy and complete the following reactions:

1) Magnesium carbonate + hydrochloric acid

2) Calcium carbonate + hydrochloric acid

3) Sodium carbonate + sulphuric acid

Mg H ClMg

Cl

Cl

HH

H Cl

C

O

O

OO

OO

C

21/04/23Reactions of metal oxides with acidA metal oxide is a compound containing a metal and oxide. They are

sometimes called BASES. For example:

Mg O NaNa

O

O

Al

AlO

O

Magnesium oxide

Sodium oxide Aluminium oxideMETAL OXIDE + ACID SALT + WATER

Copy and complete the following reactions:

1) Magnesium oxide + hydrochloric acid

2) Calcium oxide + hydrochloric acid

3) Sodium oxide + sulphuric acid

Mg OH Cl

Mg ClCl

HH OH Cl

21/04/23Electrolysis of Hydrochloric Acid

++++

----

Positive electrode

H+

H+

H+

Negative electrode

Cl-

Cl-

Cl-Hydrochloric acid

21/04/23Testing for Hydrogen

“POP”

21/04/23Testing for Chlorine

Chlorine “bleaches” damp indicator paper. It is also a toxic gas so don’t breathe it! This leads to problems when it comes to large-scale manufacture of chlorine gas.

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Positive electrode

Negative electrode

Electrolysis of seawater

Sodium chloride solution (seawater)

NaCl(aq) Sodium hydroxide (NaOH(aq))

Seawater is a mixture of water and salt (sodium chloride) and we can electrolyse it to produce chlorine and other useful products:

Chlorine gas (Cl2) Hydrogen gas (H2)

21/04/23Uses of chlorine

Polyvinylchloride (PVC) is made up of lots of monomers of vinyl chloride (chloroethene):

Chloroethene monomer

C C

Cl

H

HH

C C

Cl

H

HH

Lots more Chloroethene

monomers

H

C C

H

HH

H

C C

H

HH

Polyvinylchloride (PVC)

Chlorine is also used in the manufacture of bleach. Sodium hydroxide is reacted with chlorine to form sodium hypochlorite (bleach):

Cl2 + 2 NaOH → NaCl + NaClO + H2O

21/04/23Electrolysis of Water

Positive electrode

Negative electrode

Water

H2O

Water is two atoms of hydrogen and one atom of oxygen. It can be electrolysed to break it down:

Oxygen gas (O2) Hydrogen gas (H2)

OH H

21/04/23Testing for Oxygen

Oxygen will relight a glowing splint

21/04/23Topic 4 – Obtaining and Using Topic 4 – Obtaining and Using MetalsMetals

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Extracting MetalsExtracting Metals

A METAL ORE is a mineral or mixture of minerals from which it is “economically viable” to extract some metal.

To “extract” a metal from a metal oxide we need to REDUCE the oxygen. This is called a REDUCTION reaction. To put it simply:

Most ores contain METAL OXIDES (e.g. rust = iron oxide).

Some definitions:

Iron OxideIron ore

“Reduce” the oxygen to make iron

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OxideIron

How do we do it?How do we do it?Potassium

Sodium

Calcium

Magnesium

Aluminium

Carbon

Zinc

Iron

Tin

Lead

Copper

Silver

Gold

Platinum

Metals ABOVE CARBON, because of their high reactivity, are extracted by ELECTROLYSIS, which is very expensive!Metals BELOW CARBON are extracted by heating them with carbon in a BLAST FURNACE. This is a “displacement reaction”

These LOW REACTIVITY metals won’t need to be extracted because they are SO unreactive you’ll find them on their own, not in a metal oxide

Carbon

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Extracting metalsExtracting metals1) What is an ore?

2) In what form are metals usually found in the Earth?

3) How do you get a metal out of a metal oxide?

4) What is this type of reaction called?

Type of metal Extraction process Examples

High reactivity (i.e anything above carbon)

Middle reactivity (i.e. anything below carbon)

Low reactivity

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Extracting AluminiumExtracting Aluminium

Aluminium has to be extracted from its ore by electrolysis. This is because aluminium is very ___________ and so it cannot be extracted using ______. The amount of energy and _____ required to extract aluminium and other metals is very high and so ________ is a much better option.

Words – reactive, recycling, money, carbon

21/04/2321/04/23Copper, Aluminium and Copper, Aluminium and TitaniumTitanium

Metal Uses and why Extraction method

Problems

Copper Electrical wires – good

conductor

Electrolysis Limited supply

Gold Jewellery – attractive and

resistant to corrosion

None needed – its unreactive

so you find it in the Earth as

gold

Limited supply and very

expensive

Aluminium and titanium

Planes – light and corrosion

resistant

Complicated and expensive

Expensive and difficult to

extract

21/04/2321/04/23Using impurities to strengthen Using impurities to strengthen IronIron

In pure iron all impurities are removed. This makes the iron soft:

Adding 1% impurities makes the iron much stronger:

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AlloysAlloysSteel is an “alloy” – i.e. a mixture of metals. Here are other alloys:

Gold mixed with copper

Aluminium mixed with magnesium and copper

Aluminiun mixed with chromium

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Making steelMaking steel

Amount of carbon added (%)0.5% 1%

Strong

Weak

1.5%

Strength

Hardness

Steel with a low carbon content is easily shaped

Steel with a high carbon content is strong but brittle

Steel with chromium and nickel is called stainless steel

21/04/23Smart Alloys

A “smart alloy” is one that can “remember” its original state after being bent or stretched.

These glasses are made from a “smart” material – if they are bent they will return to their original shape. They could be made from an alloy called “nitinol” (an alloy of nickel and titanium) which can be bent but then returned to its original shape simply by heating to its “transformation temperature”.

21/04/23Gold alloys

Gold can be mixed with other metals to make alloys with different properties. For example:

24-Carat gold

“Pure gold” – 99.99% of the atoms in this bar are gold atoms (fineness off 999.9). Pure and malleable but soft.

9-Carat gold

“9 carat gold” – around 9/24ths of the atoms in these earrings are gold atoms. Harder than pure gold but less malleable.

21/04/23Materials in a Car

Alloy wheels

Steel bodyPlastic trim

Glass windscreen

Copper wires

Nylon seatbelts

21/04/23Iron or aluminium?

Aluminium:

Does not corrode

Less dense so it’s lighter

Iron:

Cheaper than aluminium

Magnetic so easily recycled

Most cars are made from steel (an alloy of carbon)

From 2015 95% of a car will have to be made from recycled material. What are the advantages of this?

21/04/23Recycling

Why recycle metals?

1) Less space will be needed for landfill sites

2) Recycled metals only need about 1/10th of the energy to produce compared to producing new metals

3) Recycling saves on raw materials

4) Less excavation and mining costs

21/04/23Rusting

Rust is a hydrated form of iron oxide. It is formed when iron and/or steel combines with oxygen and water in an oxidation reaction:

Iron + oxygen + water hydrated iron (III) oxide

21/04/23Rusting

Task: To investigate what causes rusting

Tube 1 – drying agent

Tube 2 – boiled water

Tube 3 – water + air

Tube 4 – water + air

+ salt

21/04/23Rusting

Task: To investigate what causes rusting

No rust No rust Rust Lots of rust

Iron + oxygen + water hydrated iron oxide

21/04/23More on Redox Reactions

Basically, during a redox reaction electrons are either lost or gained:

The Golden Rule: OILRIG

Oxidation Is Loss (of electrons)

Reduction Is Gain (of electrons)

For example:

Fe Fe2+

2Cl- Cl2

These reactions both involve the loss of electrons – they are Oxidation reactions

Fe2+ Fe

Cl2 2Cl-

These reactions both involve the gain of electrons – they are Reduction reactions

21/04/23Reducation and Oxidation

Some examples of reduction:

Aluminium + iron oxide aluminium oxide + ironheat

2Al(s) + Fe2O3(s) Al2O3(s) + 2Fe(s)heat

Lead oxide + carbon lead + carbon dioxideheat

2PbO(s) + C(s) 2Pb(s) + CO2(s)heat

An example of oxidation:

Magnesium + oxygen magnesium oxideheat

Mg(s) + O2(s) 2MgO(s)heat

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Topic 5 – FuelsTopic 5 – Fuels21/04/23

21/04/23Fuels

Fuels are substances that can be used to release useful amounts of energy when they burn, e.g.

Oil GasWood Coal

These fuels are called “fossil fuels” and are described as being “non-

renewable”.

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Crude OilCrude Oil

21/04/2321/04/23Hydrocarbons and crude Hydrocarbons and crude oiloil

Longer chains

mean…

1. Less ability to

flow

2. Less flammable

3. Less volatile

4. Higher boiling

point

Incre

asin

g le

ng

th

Crude oil is a mixture of HYDROCARBONS (compounds made up of carbon and hydrogen). Some examples:

Ethane

C C

HH

H

HH

H

Butane

C C

HH H

HH

H C C H

H

HH

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Distillation revisionDistillation revision

This apparatus can be used to separate water and ink because they have different _____ ______. The ______ will evaporate first, turn back into a _______ in the condenser and collect in the _______. The ink remains in the round flask, as long as the _______ does not exceed ink’s boiling point. This method can be used to separate crude oil.

Words – temperature, boiling points, water, beaker, liquid

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

Fractions with low boiling points condense at the top

Fractions with high boiling points condense at the bottom

21/04/23Burning HydrocarbonsBurning hydrocarbons will produce water, carbon dioxide and energy:

C

H

H

H

HO

O

OO

OH H

OH H

CO

O

Methane Oxygen+ Water+Carbon dioxide

In this reaction the hydrocarbon is oxidised.

21/04/23Testing for Carbon Dioxide

Gas

Limewater turns milky/cloudy

Limewater

21/04/23Burning HydrocarbonsLots of oxygen:

Some oxygen:

Little oxygen:

C

H

H

H

HO

O

OO

OH H

OH H

CO

O

Methane Oxygen+ Water+Carbon dioxide

Oxygen+

OO

OO

OO

Methane

C

H

H

H

H

C

H

H

H

H

Carbon monoxid

e

CO

CO

Water+

OH H

OH H

OH H

OH H

CC

H

H

H

H

Methane

OO

Oxygen+

OH H

OH H

Water+Carbon

21/04/23Why Carbon Monoxide is Dangerous

Basically, carbon monoxide “sticks” to red blood cells instead of oxygen, causing anybody inhaling it to essentially suffocate:

CO 1) Carbon Monoxide is breathed in

2) The molecule “sticks” to red blood cells instead of oxygen

3) The red blood cells transport the “carboxyhaemoglobin” molecule to the rest of the body and the body’s cells are starved of the oxygen needed for respiration.

Carbon monoxide is odourless, colourless and non-irritating so it’s very difficult to detect!

21/04/23Incomplete Combustion

As well as producing carbon monoxide, incomplete combustion can also produce soot:

Little oxygen:

CC

H

H

H

H

Methane

OO

Oxygen+

OH H

OH H

Water+Carbon

“Soot”

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Burning Fossil FuelsBurning Fossil FuelsBurning fossil fuels like oil and coal causes pollution.

Oil contains carbon:

C

H

H

H

HO

O

OO

OH H

OH H

CO

O

Carbon dioxide is a “greenhouse gas” – it helps cause global warming

Coal contains carbon, sulfur and other particles:

sulfur + oxygen sulfur dioxide

Sulfur dioxide causes acid rain. Other particles can cause “global dimming” – sunlight is absorbed by the particles in the atmosphere.

21/04/23Global Warming

Facts:

1) The 10 warmest years of the last century have all occurred within the last 15 years

2) Sea level has risen by between 12 and 24cm in the last 100 years

3) Rainfall has risen by 1%

21/04/23The Greenhouse EffectWe get heat from the sun:

A lot of this heat is _______ back into space.

However, most of it is kept inside the Earth by a layer of gases that prevent the heat escaping by _______ and then re-radiating it back again.This is called the _________ Effect. It has always been around, but is

currently being made worse due to:

1) Burning (releasing CO2)

2) __________ (removing trees that remove CO2)

3) Increased micro organism activity (from rotting ______)

4) Cattle and rice fields (they both produce _______)

These changes will cause GLOBAL WARMING and RISING SEA LEVELSWords – methane, radiated, absorbing, deforestation, waste, greenhouse

21/04/23Carbon Dioxide and Global WarmingGlobal levels of Carbon Dioxide in PPM

Is there a link?

21/04/23Reducing the amount of Carbon Dioxide

Scientists are trying to reduce the amount of carbon dioxide in the atmosphere through a number of possibilities:

1) “Iron seeding” – this is the process where iron is intentionally put in seawater to help produce more phytoplankton which then increases photosynthetic activity, therefore reducing the amount of CO2 in the atmosphere.

Aerial view of phytoplankton near Argentina

2) Converting CO2 into hydrocarbons – carbon dioxide can be converted into hydrocarbons and then stored in the Earth by putting it in such places as old oil fields or coal beds.

21/04/23Reducing Pollution from vehiclesA number of suggestions:

1) Buy a new, smaller, cleaner car

2) Buy a “hybrid” car

3) Convert your car to run on biodiesel

4) Make sure your car has a catalytic converter:

5) Use the train or a bus!

Carbon monoxide + oxygen carbon dioxide

Nitrogen monoxide + carbon monoxide nitrogen + carbon monoxide

21/04/23Ethanol as a biofuel

Ethanol is an important chemical. Many countries are increasing the amount of ethanol put into their petrol supplies:

Ethanol is a “clean burning” energy source and produces little or no greenhouse gases. How is it made?

Ford Escape E85 – runs on 85% ethanol

The “renewable” way

Sugar ethanol + carbon dioxide

Sugar is produced from standard crops like sugar cane and

corn

What’s the point?

When ethanol burns it only produces small amounts of carbon dioxide. Making more cars run on ethanol means having less cars that need petrol.

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Does it take more CO2 to tranport it

than it takes in from the atmosphere while growing?

Choosing a biofuel

Does it create pollution?

How much does it cost? How much land is

needed?

Is it toxic?

How much energy does it release?

Biofuels

How easy is it to grow/make?

21/04/23Choosing a fuel

How easily does it burn?

How much smoke does it

produce?Is it easy to use,

store and transport?

Is it toxic?

How much energy does it release?

Which fuel should you use?

21/04/23Hydrogen Fuel Cells

Basically, a hydrogen fuel cell combines hydrogen and oxygen to form water and release energy:

21/04/23Hydrogen Fuel Cells

Hydrogen fuel cellsvs Petrol

Advantages of fuel cells Advantages of petrol

21/04/23Energy from fuels

Copper calorimeter Water

Fuel

Spirit burner

21/04/23Where fossil fuels come from

Petrol, kerosene and diesel oil are non-renewable fossil fuels that come from crude oil.

Methane is a non-renewable fossil fuel found in natural gas.

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AlkanesAlkanesAlkanes are chemicals found in crude oil. They are SATURATED HYDROCARBONS. What does this mean?

HYDROCARBONS are molecules that are made up of hydrogen and carbon atoms

SATURATED means that all of these atoms are held together by single bonds, for example:

Ethane

Alkanes are fairly unreactive (but they do burn well). The general formula for an alkane is CnH2n+2

C C

HH

H

HH

H

Butane

C C

HH H

HH

H C C H

H

HH

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Drawing AlkanesDrawing AlkanesInstead of circles, let’s use letters…

Butane

H

C C

H

HH

H

C C

H

HH

H H

Methane

H

C H

H

H

Ethane

H

H

C C

H

HH

H

Propane

H

C H

H

H

C C

H

HH

H

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

Ethane Ethene

Butane Butene

This double bond means that alkenes have the potential to join with other molecules – this make them REACTIVE. Alkenes turn bromine water colourless.

ALK

AN

ES

ALK

EN

ES

21/04/23

Testing for alkenesTesting for alkenes21/04/23

Oil Bromine goes colourless

Bromine water

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Drawing AlkenesDrawing Alkenes

Propene (n=3)

H

C H

H

H

C C

H

H

Ethene (n=2)

H

H

C C

H

H

Butene (n=4)

H

C C

H

HH

H

C C

H

H H

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CrackingCrackingShorter chain hydrocarbons are in greater demand because they burn easier. They can be made from long chain hydrocarbons by “cracking”:

Butane

Ethane

For example, this bond can be “cracked” to give these:

Ethene

21/04/2321/04/23CrackingCracking

This is a THERMAL DECOMPOSITION reaction, with clay used as a catalyst

1) Carbon dioxide causes the _________ effect

2) Sulfur dioxide causes _____ _____

3) Plastics are not _____________

Cracking is used to produce plastics such as polymers and polyethanes. The waste products from this reaction include carbon dioxide, sulfur dioxide and water vapour. There are three main environmental problems here:

Long chain hydrocarbon

Heated catalyst

Gaseous hydrocarbon

Liquid hydrocarbon

21/04/23Composition of Crude Oil

Consider the following data for different fractions from crude oil:

Amount

PetrolDeman

dSupply

Amount

Bitumen

Demand

Supply

How do people on the oil business solve this problem?

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Monomers and PolymersMonomers and Polymers

C CHH

HH

Ethene

Here’s ethene again. Ethene is called a MONOMER because it is just one small molecule. We can use ethene to make plastics…

Step 1: Break the double bond

Step 2: Add the molecules together:

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

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Another way of drawing it…Another way of drawing it…Instead of circles, let’s use letters…

Ethene

C C

HH

HH

C C

HH

HH

Ethene

H

C C

H

HH

H

C C

H

HH

Poly(e)thene

General formula for addition polymerisation:

C Cn C C

n

e.g. C Cn

H CH3

HH

C Cn

H CH3

HH

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Some examplesSome examples

C Cn

H H

HH

C Cn

H H

HCl

C CnH H

HH

C CnH H

HCl

C CnH Cl

HBr

C Cn

H Cl

HBr

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Uses of addition polymersUses of addition polymersPoly(ethene) Poly(propene)

Poly(chloroethene), PVC

Poly(styrene)

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Disposal of plasticsDisposal of plastics1) Landfill sites - most plastics do not _________ which means that landfill sites are quickly filled up. Research is being carried out on __________ plastics.

2) Burning – this releases carbon dioxide which causes the ________ effect, as well as other ________ gases.

3) _______ – the best option, but difficult because of the different types of plastic

Words – recycling, greenhouse, decompose, biodegradable, poisonous

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Biodegradable carrier bagsBiodegradable carrier bags21/04/23

This carrier bag has been made with flax fibre from industrial waste.