Mary Rodriguez

CHEMISTRY REVIEW C10-C14

METALS

• 1 Distinguish between metals and nonmetals by their general physical and chemical properties.

• 3 Explain why metals are often used in the form of alloys.

• 2 Identify and interpret diagrams that represent the structure of an alloy.

10.1 PROPERTIES OF METALS

Metals

Often have 1-3 outer valence electrons

Lose valence electrons quite easily.

Form oxides that are basic

Good reducing agents

NonMetals

Often have 4-8 valence electrons

Gain or share valence electrons easily.

Good oxidizing agents

Form oxides that are acidic

CHEMICAL DIFFERENCES

Metals

Good electrical conductors

Good heat conductors

Malleable – Can be beaten into thin sheets

Ductile – Is able to be stretched into wire.

Mostly solid at room temperature

Non-metals

Poor conductor of electricity

Poor conductor of heat

Nonductile

Solids, liquids or gases at room temperature

PHYSICAL PROPERTIES

the mixture of two or more metallic elements.

two different types of atoms incoherently mixed together, without any apparent order. (In GCSE, if you see this, you

can almost assume that the diagram is suggesting an alloy.)

ALLOYS

What makes alloys special is that since the atoms are all jumbled together of different sizes, it is much more difficult for alloy layers to slide over each other, so alloys are harder

than pure metals.

An alloy has the properties of both metals, therefore it is beneficial when two metals can mix to negate the

weaknesses of each other

ALLOYS

Metals such as Copper or iron are too soft for many uses. Therefore, these metals are often mixed with other methods

to acquire make it harder. Additionally, an alloy has the properties of both metals, therefore it is beneficial when

two metals can mix to negate the weaknesses of each other.

Brass is used in electrical fittings, 70% copper and 30% zinc.

Bronze is used for bearings and bells, and it often composed composed of 80% copper and 20% Tin.

Duralumin is used for airplane manufacture, 96 % aluminium and 4% copper and other metals.

EXAMPLES

METAL IMAGES

This strong bonding generally results in dense, strong materials with high melting and boiling points. Usually a relatively large

amount of energy is needed to melt or boil metals.

Good conductors of electricity/heat because these 'free' electrons carry the charge of an electric current when a potential difference (voltage!) is applied across a piece of metal. The 'hot' high kinetic

energy electrons move around freely to transfer the particle kinetic energy more efficiently to 'cooler' atoms.

Typically - silvery surface (tarnished by corrosive oxidation in air and water.

Metals are very malleable (readily bent, pressed or hammered into shape.) The layers of atoms can slide over each other without

fracturing the structure When planes of metal atoms are 'bent' or slide the electrons can run in between the atoms and maintain a

strong bonding situation

PROPERTIES OF METALS

The crystal lattice of metals consists of ions (NOT atoms) surrounded by a 'sea of electrons' forming another type of giant lattice.

The outer electrons (-) from the original metal atoms are free to move around between the positive metal ions formed (+).

These free or 'delocalised' electrons are the 'electronic glue' holding the particles together.

There is a strong electrical force of attraction between these free and mobile electrons (-) and the 'immobile' positive metal ions (+) and this is the

metallic bond. Metallic bonding is not directional – there is an attractive force between the mobile electrons that act in every direction about the fixed (immobile) metal

ions. Metals can become weakened when repeatedly stressed and strained ('metal

fatigue' or 'stress fractures'. )

It is important develop alloys which are well designed, well tested and will last the expected lifetime of the structure whether it be part of an aircraft (eg titanium aircraft frame) or a part of a bridge (eg steel suspension cables).

METAL BONDING

• 1 Place in order of reactivity: potassium, sodium, calcium, magnesium, zinc, iron, hydrogen and copper, by reference to the reactions, if any, of the elements with water or steam, dilute hydrochloric acid (except for alkali metals).

• 2 Compare the reactivity series to the tendency of a metal to form its positive ion, illustrated by its reaction, if any, with: the aqueous ions of other listed metals, the oxides of the other listed metals.

• 3 Deduce an order of reactivity from a given set of experimental results.

10.2 REACTIVITY SERIES

REACTIVITY SERIES

Metal Reactivity Extraction

Potassium Reacts with water Electrolysis

Sodium

Calcium

Magnesium Reacts with acids

Zinc Smelting with coke (Blast Furnace)Iron

Hydrogen Included for comparison

Copper May react with strongly oxidizing acids

Heat or physical extraction

THE TENDENCY OF A METAL TO FORM ITS POSITIVE ION

• Elements at the top form positive ions the easiest, and this tendency decreases as you go down the group. Valence electrons are more easily lost up in the reactive series to form ionic bonds.

• Reaction of Potassium with Water

2K (s) + 2H2O (l) —-> 2KOH (aq)  + H2 (g)

Potassium + Water —-> Potassium Hydroxide + Hydrogen• Reaction of Magnesium with Water

2Mg (s) + 2H2O —> 2Mg(OH)2 (aq) + H2

Magnesium + Water —> Magnesium Hydroxide + Hydrogen

• Reaction of Magnesium with Steam

Magnesium + Steam —> Magnesium Oxide + Hydrogen

• Let’s take three unknown metals X,Y and Z• We will put these three metals in three separate beakers

immersed with Hydrochloric Acid• Observe• In the exam, you are likely to see these type of questions.• The beaker which produces the most bubbles, effervescence is

likely to contain the most reactive metal.

• However, for this to be a successful experiment, we have to ensure some variables are controlled. We call this controlled variables.

Time allowed for reaction to occur.

Temperature of acid

Initial surface of metal

Volume of acid

Many more.

EXPERIMENTAL RESULTS

• 1 Describe the use of carbon in the extraction of some metals from their ores.

• 2 Describe the essential reactions in the extraction of iron in the blast furnace.

• 3 Relate the method of extraction of a metal from its ore to its position in the reactivity series.

10.3 EXTRACTION OF METALS

Carbon is oxidised to Carbon Dioxide

Coke, which consists mostly of carbon, is burned to give off heat.

CARBON IN EXTRACTION OF METALS

BLAST FURNACE

1. Hot blast from Cowper stoves

2. Melting zone3. Reduction zone of

ferrous oxide4. Reduction zone of

ferric oxide5. Pre-heating zone6. Feed of ore,

limestone and coke7. Exhaust gases8. Column of ore, coke

and limestone9. Removal of slag10.Tapping of molten

pig iron11.Collection of waste

gases

• Iron Ore: The major component of iron is hematite, which is mainly composed of Iron (III) oxide, mixed with some sand and other compounds

• Limestone: Mainly composed of Calcium Carbonate, CaCO3

• Coke: Mainly made from coal, and it is composed nearly out of pure carbon.

INSIDE BLAST FURNACE

• Stage 1: The coke is burned, which gives off heat.

The hot air starts burning the coke and allows it to react the oxygen in the air to produce Carbon Dioxide

Carbon + Oxygen → Carbon Dioxide

C (s)  + O2 (g) → CO2 (g)• Stage 2: Carbon Monoxide  is made

The Carbon Dioxide subsequently reacts with more coke:

Carbon + Carbon Dioxide → Carbon Monoxide

C(s)   + CO2 →2CO (g)• Stage 3: Iron Oxide (III) is reduced.

Only in this step does extraction actually occur.

The Carbon Monoxide reacts with the iron ore, producing liquid iron, something we actually want.

Iron (III) oxide + Carbon Monoxide → Iron + Carbon Dioxide

Fe2O3 (s) + 3CO (g) → 2Fe (l) + 3CO2 (g)

STAGES

• The limestone breaks down in the heat of the furnace• CaCO3 → CaO + CO2• Calcium Carbonate → Calcium Oxide + Carbon Dioxide• The calcium oxide that is formed reacts with sand, which

is mainly silicon dioxide.• This reaction forms slag which runs down the furnace

and then floats on the iron.

LIMESTONE

Metal Ion Reactivity Extraction

Cs Cs+

reacts with water

Electrolysis

Rb Rb+

K K+

Na Na+

Li Li+

Ba Ba2+

Sr Sr2+

Ca Ca2+

Mg Mg2+ reacts with acidsAl Al3+

C included for comparisonMn Mn2+

reacts with acids

smeltingwith coke

Zn Zn2+

Cr Cr2+

Fe Fe2+

Cd Cd2+

Co Co2+

Ni Ni2+

Sn Sn2+

Pb Pb2+

H2 H+ included for comparisonSb Sb3+

may react with some

strongly oxidizing acids

heat orphysicalextraction

Bi Bi3+

Cu Cu2+

Hg Hg2+

Ag Ag+

Au Au3+

Pt Pt2+

The paradigm here is that the most reactive metals such as Sodium is extracted through electrolysis.

The less reactive metals, typically those lower than Carbon in the reactivity series are extracted via the Blast Furnace.

Lastly, those metals such as gold which are extremely unreactive are usually not extracted because they are so unreactive that they can often be found native or simply

alone, by themselves.

EXPLANATION

1. Iron Ore: Iron ore is extracted via reduction through the blast furnace.

Iron (III) Oxide + Carbon Monoxide → Iron + Carbon Dioxide

2. Aluminium Ore: This is usually just aluminium oxide. Aluminium is higher than carbon in the reactivity series, so it is therefore extracted through electrolysis.

Aluminium Oxide → Aluminium + Oxygen

Nice and simple.

3. Zinc Blende. Usually just Zinc Sulfide. This is roasted in air to produce Zinc Oxide and Sulfur Dioxide

Zinc Sulfide + Oxygen → Zinc Oxide + Sulfur Dioxide

EXAMPLES OF REACTIONS

• 1 Explain the use of aluminium in aircraft manufacture in terms of the properties of the metal and alloys made from it.

• 3 Explain the use of aluminium in food containers because of its resistance to corrosion.

• 2 Explain the use of zinc for galvanising steel, and for sacrificial protection.

10.4 USES OF METALS

AIR AND WATER

• 1 Describe a chemical test for water.• 2 Describe and explain, in outline, the purification of the water supply by

filtration and chlorination.• 3 State some of the uses of water in industry and in the home.• 5 Describe the composition of clean air as being a mixture of 78%

nitrogen, 21% oxygen and small quantities of noble gases, water vapour and carbon dioxide.

• 6 State the common air pollutants as carbon monoxide, sulfur dioxide and oxides of nitrogen, and describe their sources.

• 9 State the adverse effect of common air pollutants on buildings and on health.

• 10 Describe the formation of carbon dioxide:

• as a product of complete combustion of carbon-containing substances,

• as a product of respiration,

• as a product of the reaction between an acid and a carbonate.

C11. AIR AND WATER

• 12 Describe the rusting of iron in terms of a reaction involving air and water, and simple methods of rust prevention, including paint and other coatings to exclude oxygen.

• 13 Describe the need for nitrogen-, phosphorus- and potassium-containing fertilisers.

• 14 Describe the displacement of ammonia from its salts by warming with an alkali.

• 4 Describe the separation of oxygen and nitrogen from liquid air by fractional distillation.

• 7 Explain the presence of oxides of nitrogen in car exhausts and their catalytic removal.

• 8 Explain why the proportion of carbon dioxide in the atmosphere is increasing, and why this is important.

• 11 Describe the essential conditions for the manufacture of ammonia by the Haber process including the sources of the hydrogen and nitrogen, i.e. hydrocarbons or steam and air.

AIR AND WATER

• Here are a few ways in which you can use to test for the presence of water:

• Test the liquids boiling point. Water boils at precisely 100 degrees and freezes at exactly 0 degrees.

• If you add water to Anhydrous Copper Sulphate Powder, it forms a blue solution and may give out heat.

• Add Anhydrous Cobalt Chloride which is blue in color. If water is present, should change to color pink.

CHEMICAL TEST FOR WATER

• Water extracted from the earth is always infested with impurities. This water might be contaminated with disease and bacteria. That is why it is crucial to “purify” the water before it is drank. This is done by two processes, Filtration and Chlorination.

• Here is how it works:

• Water is extracted from reservoirs and sent to be “treated”

• The water is first passed through a filter to filter out large objects such as rocks or mud.

• Smaller particles in the water is removed by adding Aluminium Sulfate which causes the smaller particles to stick together in large pieces and settle down the filter.

• Water is now passed through sand and gravel filters which continue to filter off the smaller particles and kills bacteria.

• Now its time for chlorination

• Chlorine gas is first bubbled through the water to kill the bacteria that exists in the water.

• Sodium Hydroxide may be added in the water to prevent the water from being acidic from the chlorine.

• Water is delivered to the people that need them.

PURIFICATION OF WATER

Irrigation

Cooling

Recreation

Agricultural

Industrial use

Shower

USES OF WATER

FRACTIONAL DISTILLATION

• Clean air is cooled to around -80 degrees, Carbon Dioxide sublimes into a solid, water vapour condenses then freezes into ice to be collected.

• Cold Air is put into a compressor which increases the pressure to around 100 atm. This causes the air to warm up.

• The re-cooled, compressed is now allowed to expand and lose its pressure, which allows it to cool further.

• The air is again compressed and then expanded to continue to be cooled. This continues until all liquids liquefy.

• The cold air is brought into a fractionating column (as seen above) and slowly left to warm.

• Gases separate according to their boiling points. The gas with the lowest boiling points evaporate first.

COMPOSITION OF AIR

COMMON AIR POLLUTANTS

CARBON MONOXIDE

• Poisonous pollutant of air• Main source is factories that burning Carbon-containing

fossil fuels as carbon is one of the products of incomplete combustion of fossil fuels.

• Contributes to acidic rain• Main Source comes from two products: 

1. Combustion of sulphur

2. Extraction of metals from their sulfide ores

• Mixes with water vapour of cloud and air.• This forms Sulphuric Acid (H2SO4)• When it rains, the rain water becomes acidic .• Acidic water is dangerous because it causes the death of

sea creatures, acidifies soil which can cause death to plants and cause deforestation.

• May also cause lung cancer

SULPHUR DIOXIDE

• Formed in high temperatures when nitrogen and oxygen react.

• In Cars, the engine operates at a high temperature, giving the nitrogen and the oxygen in the air and engine a chance to react, hence forming nitrogen monoxide. Nitrogen monoxide further reacts with the oxygen in the air to form Nitrogen Oxide.

• Nitrogen oxide is dangerous in that it also rises in the air and mixes with rain water to form nitric acid. This can also cause acid rain

• Additionally, Nitrogen oxygen can cause certain respiratory problems.

OXIDES OF NITROGEN

• Oxides of nitrogen are present in car exhausts, and these can cause problems both to the environment and us humans. Therefore, scientists need to find a way to remove the “oxides of nitrogen” in cars.

• This is done through a catalytic converter• The catalytic converter is fitted at the end of the car

exhaust.• The purpose of the catalytic converter which catalyzes

the reaction between the Nitrogen Oxide and Carbon Monoxide, which in turn produces two harmless separate gases, nitrogen and carbon dioxide. The carbon dioxide comes from the fact that carbon is already present in the cars engine.

THE PRESENCE OF OXIDES OF NITROGEN IN CAR

EXHAUSTS

Equation of the Reactions

2NO + 2CO → 2CO2 + N2Nitrogen Oxide + Carbon Monoxide → Carbon Dioxide + Nitrogen

2NO2 + 4CO → 4CO2 + N2Nitrogen Dioxide + Carbon Monoxide → Carbon Dioxide + Nitrogen

• The Sun sends energy to the earth in two discrete forms, heat and light.

• Some of the heat is reflected back to the sun/space, but some is trapped in the earth.

• This is caused by the existence of some gases and we call this the Greenhouse effect.

• The primary Greenhouse gases are Carbon Dioxide and Methane.• The greenhouse effect is a serious threat to our world. The reason for

this can be described by the proliferation of greenhouse gases which causes the greenhouse effect. Increased combustion of carbon in industries which mass produce Carbon Dioxide as a side product and the cutting down of trees which release CO2 via respiration are two major reasons why the greenhouse effect is becoming more serious.

• The increase of heat trapped in the earth causes an average rise in sea level and global average temperatures, and we call this effect Global warming

INCREASE IN CARBON DIOXIDE

• Formed in power stations by the complete combustion of Carbon containing fuels.

• Formed as a product as respiration.• When an acid reacts with a carbonate, Carbon Dioxide is

usually formed.

FORMATION OF CARBON DIOXIDE

THE HABER PROCESS

• The Haber Process manufactures Ammonia from Hydrogen and Nitrogen)

• The reaction is as follows:

• N2 + 3 H2 ⇌ 2 NH3

• Conditions required to manufacture this:

• High temperature (400-450°C )

• Iron catalyst

• High pressure

• Sources:

• Hydrogen – from natural gases

• Nitrogen – from the air

SULFUR

• 1 Describe the manufacture of sulfuric acid by the Contact process, including essential conditions.

• 2 Describe the properties of dilute sulfuric acid as a typical acid.

C12. SULFUR

The Contact Process is a method used to produce Sulphuric Acid.

CONTACT PROCESS

Conditions for Contact Process to occur• 450C°• 2-9 atm

(pressure)• Vanadium Pent-

oxide (V2O5) Catalyst

Colored

Corrosive liquid

Strong oxidizing agent

Reacts violently with bases.

Doesn’t conduct electricity

Insoluble in Water

Brittle

PROPERTIES OF DILUTE SULFURIC ACID

CARBONATES

1 Describe the manufacture of lime (calcium oxide) from calcium carbonate (limestone) in terms of the chemical

reactions involved, and its uses in treating acidic soil and neutralising industrial waste products.

C13. CARBONATES

• Carbonates are “salts” of Carbonic Acids (H2CO3).• Calcium Carbonate (CaCO3) is an especially important

Carbonic Acid.

Uses of Calcium Carbonate• Helping extraction of iron from its ore• Manufacture of cement

CALCIUM CARBONATE

• One industrial use of Calcium Carbonate is that it can be used to make “lime”. This process takes place in a kiln, and is largely based on the thermal decomposition of Calcium Carbonate. Limestone is inserted in the Kiln and then is heated. The bottom of the Kiln is both where air is blown in and where lime is collected.  Carbon dioxide is also produced.

• We can describe this reaction with a simple equation, which you will have to memorize.

• CaCO3 (Limestone) ⇌ CaO (Lime) + CO2 (Carbon Dioxide)

MANUFACTURE OF LIME

• Used to neutralize soil acidity in farms. This is because lime is a basic oxide, so therefore can be used to neutralize the acidity of the soil.

• Another use is to neutralize sulphur waste in power stations. This is also because Sulphur is acidic whilst lime is a basic oxide. And as we’ve learned before, an acid and a basic involves a process of neutralization.

USES OF LIME

ORGANIC CHEMISTRY

• 1 Recall coal, natural gas and petroleum as fossil fuels that produce carbon dioxide on combustion.

• 3 Name methane as the main constituent of natural gas.• 4 Describe petroleum as a mixture of hydrocarbons and its

separation into useful fractions by fractional distillation.• 5 State the use of:

• refinery gas for bottled gas for heating and cooking,

• gasoline fraction for fuel (petrol) in cars,

• diesel oil / gas oil for fuel in diesel engines.

• 2 Understand the essential principle of fractional distillation in terms of differing boiling points (ranges) of fractions related to molecular size and intermolecular attractive forces.

• https://www.acceleratedstudynotes.com/2012/02/28/igcse-coordinated-science-introduction-to-organic-compounds/

14.1 FUELS

FOSSIL FUELS

Natural gas, coal, petroleum(oil)

Form over millions of years

Produce CO2 during combustion

Provides great amount of energy

Nonrenewable

Petroleum: These are formed from the remains of dead organisms that fell to the ocean floor and were then buried by the thick

sediment. The high pressure in which the dead organisms are buried eventually converts the dead organisms into petroleum, but this is a

process that takes millions of years.

Natural Gas: This is composed mainly of methane and is often found with petroleum. High temperatures and pressure causes the

compounds to break down into gas.

Coal: This is the remain of lush vegetation that grew in ancient swamps. Over the millions of years, high pressure and heat

eventually converted the vegetation into coal.

REASONS

USES

Refinery gas-bottled gas for heating and cooking

(natural gas, methane, propane, butane )

Gasoline-fuel in cars

Diesel Oil / Gas Oil-fuel in diesel engines

Mixture of hydrocarbons and its separation into useful fractions by fractional distillation

PETROLEUM

FRACTIONAL DISTILLATION

Separation of a mixture into its component parts

Principle-Every liquid has a different boiling point

Higher molecular size=Higher BP

Stronger intermolecular forces=Higher BP

Petroleum is a mixture of hundreds and hundreds of different hydrocarbons.

Putting all these mixtures together isn’t really productive.

In order to solve this problem, we have to refine the petroleum in the process of Fractional Distillation.

Acknowledge fractional distillation in terms of differing boiling points of fractions related to molecular size and

attractive forces. The compounds with large molecules are likely to have a higher boiling point, so therefore condense

faster and are collected on a lower position in the fractionating column.

BOILING POINTS

FRACTIONAL DISTILLATION

Steps:1. When you heat the petroleum,

the compounds start to evaporate as particles will more Kinetic Energy and therefore will more likely be able to break bonds. The compounds which are smaller and lighter evaporate first as it takes less energy to evaporate these.

2. The hot vapour rises and the vapour then condenses in the cool test tube.

3. when the thermometer reaches 100 degrees, the first test tube is then replaced with an empty one. The liquid in the first test tube is the first fraction from the distillation.

4. Repeat, replacing the test tube at 150 degrees, 200 degrees, and 250 degrees.

FRACTIONATING TOWER

Petroleum is pumped in at the base.

The compounds start to evaporate.

Those with the smallest molecules evaporate off first, and rise to the top of the tower.

Others rise only part of the way, this is entirely dependent on their boiling points, and then condenses.

The compounds are collected in their respective levels before they condense.

Refinery gas

Used for bottled gas for heating and cooking,

Gasoline fraction

Used for fuel (petrol) in cars.

 Diesel oil/gas oil

Used for fuel in diesel engines.

USES

• 1 Identify and draw the structures of methane, ethane, ethene and ethanol.

• 3 State the type of compound present, given a chemical name ending in -ane, -ene and -ol, or a molecular structure.

• 2 Describe the concept of homologous series of alkanes and alkenes as families of compounds with similar properties.

• 4 Name, identify and draw the structures of the unbranched alkanes and alkenes (not cis-trans), containing up to four carbon atoms per molecule.

14.2 INTRODUCTION TO ORGANIC COMPOUNDS

METHANE

• Main component of natural gas

ETHANE

ETHENE

ETHANOL

ALKANES

Simplest organic compound

Single bonds

Covalently bonded

Composed of only Hydrogen and Carbon

Generally unreactive

Combustible

The chemistry of carbon compounds is called organic chemistry. There are millions of organic chemicals, but they can be divided into groups called homologous series. All members of a particular series will have similar

chemical properties and can be represented by a general formula.

Members in a Homologous Series have:

 

•    Same chemical reactions

•    Same functional group (Eg. –OH, ‐COOH)

•    Same general formula, Alkanes CnH2n+2, Alkenes CnH2n

•   Similar, but Different Physical Properties

 

The alkane series is the simplest homologous series. The main source of alkanes is from crude oil.

The first five members of this homologous series are:

Methane, Ethane, Propane, Butane, Pentane

ALKANES AND ALKENES: HOMOLOGOUS SERIES

-ane will usually be a Alkane.

-ene will usually form compound Alkene.

-ol will usually form Alcohol.

-yne will usually form Alkyne

ENDINGS

PRODUCTS OF COMBUSTION

Methane

Carbon Dioxide

Water

• 1 Describe the properties of alkanes (exemplified by methane) as being generally unreactive, except in terms of burning.

• 2 State that the products of complete combustion of hydrocarbons, exemplified by methane, are carbon dioxide and water.

• 3 Name cracking as a reaction which produces alkenes.• 5 Recognise saturated and unsaturated hydrocarbons

• from molecular structures,

• by their reaction with aqueous bromine.

• 4 Describe the manufacture of alkenes by cracking.• 6 Describe the addition reactions of alkenes, exemplified by

ethene, with bromine, hydrogen and steam.

14.3 HYDROCARBONS

Alkanes are generally quite unreactive, and they do not combine well with other substances. The only exception to

this is when you burn the alkane, especially methane, in the air with oxygen

SINGLE BONDS

PROPERTIES OF ALKANES

If you burn a hydrocarbon in the air with oxygen, the hydrocarbon undergoes a process called combustion,

and produces Carbon Dioxide + Water.

E.g.

Methane + Oxygen –> Carbon Dioxide + Water

CH4 + 2O2 → CO2 + 2H2O

PRODUCTS OF COMPLETE COMBUSTION

In the exam, if they give you a question showing a process where an alkane is being manufactured into alkenes, you can confidently put down cracking as the process which turns the alkane into an

alkene.

• You can make an alkene from an alkane through a process called cracking.

•  Cracking is basically a process where you break down heavier molecules into lighter hydrocarbons, as there is little industrial use

for these heavy hydrocarbons.

INA REFINERY

How cracking takes place in a refinery?

Long chain hydrocarbon is heated to be vaporized.

The vapour is passed through a catalyst.

Thermal decomposition takes place, and the alkane is decomposed into the smaller alkenes.

CRACKING

CRACKING

• H2 is produced in the cracking process.

• High temperature is needed

• Catalyst speeds up the reaction.

• Obviously, cracking ethane is an example of cracking short hydrocarbons. Most hydrocarbons are very long in terms of their molecular structure, which is why they have to be cracked in the first place!

• From molecular structures,• By their reaction with aqueous bromine.

Saturated Hydrocarbons have single C-C bonds between the atoms. Examples of saturated hydrocarbons

Unsaturated Hydrocarbons have C=C double bonds.

Examples of unsaturated hydrocarbons are alkenes.• Molecular Structures

Saturated Hydrocarbons have C-C single bonds whilst C=C is a double bond• Reaction with aqueous bromine

Get some orange solution bromine water and the suspected hydrocarbon

Add a few drops of bromine to the hydrocarbon

If the solution decolorizes (color disappears), a unsaturated hydrocarbon is present.

SATURATED AND UNSATURATED HYDROCARBONS

“An addition reaction is a process where an unsaturated alkene is turned to a saturated compound”.

 We’re going to learn how we form ethanol from ethane.

 When you crack ethane, you form ethene. As a result, hydrogen is also produced.

Ethene can react with hydrogen again, under heat, pressure and a catalyst to form ethane

Ethene can add on with water (steam) to form ethene

Ethene + Steam →  Ethanol

ADDITION REACTIONS

• 1 State that ethanol may be formed by reaction between ethene and steam.

• 3 Describe the complete combustion reaction of ethanol.• 4 State the uses of ethanol as a solvent and as a fuel.• 2 Describe the formation of ethanol by the catalytic

addition of steam to ethene.

14.4 ALCOHOLS

Hydration: Basically means water is added on. An Addition Reaction

HYDRATION

Ethene + Steam —> EthanolC2H4 + H2O —> C2H5OH• Reaction is reversible• Exothermic• High pressure and low temperature would give the

highest yield.• Catalyst is used to speed up the reaction.

Ethanol burns quite well in oxygen to give out heat:

C2H5OH (l) + 3O2 (g) → 2CO2 (g) + 3H2O (l) + heat

Additionally, carbon dioxide and water vapour is formed as a product.

COMBUSTION REACTION OF ETHANOL

1) Ethanol is often used a fuel.

2) Ethanol is often used as fuel because:

It can be made quite cheaply.

Many countries lack petroleum and need to import from other nations, so ethanol seems more cost effective.

Less impact on Carbon Dioxide levels are compared to fossil fuels.

Used for:

Motor Fuel, Rocket fuel

As a solvent

Ethanol is the alcohol in alcoholic drinks such as vodka.

Its a good solvent because it easily dissolves many substances that do not dissolve in water.

Evaporates easily so it is a suitable solvent to use in glues, printing inks, perfumes, and aftershave.

ETHANOL

USES OF ETHANOL

Drinks

The "alcohol" in alcoholic drinks is simply ethanol.

Industrial methylated spirits (meths)

Ethanol is usually sold as industrial methylated spirits which is ethanol with a small quantity of methanol added and possibly some colour. Methanol is poisonous, and so the industrial methylated spirits is unfit to drink. This

avoids the high taxes which are levied on alcoholic drinks (certainly in the UK!).

As a fuel

Ethanol burns to give carbon dioxide and water and can be used as a fuel in its own right, or in mixtures with petrol (gasoline). "Gasohol" is a petrol /

ethanol mixture containing about 10 - 20% ethanol.

Because ethanol can be produced by fermentation, this is a useful way for countries without an oil industry to reduce imports of petrol.

As a solvent

Ethanol is widely used as a solvent. It is relatively safe, and can be used to dissolve many organic compounds which are insoluble in water. It is used,

for example, in many perfumes and cosmetics.

Ethanol can be used as a solvent and a fuel

MAKING ALKENES IN THE LAB

http://www.chemguide.co.uk/organicprops/alkenes/making.html#top

• 1 Describe macromolecules in terms of large molecules built up from small units (monomers), different macromolecules having different units.

14.5 MACROMOLECULES

• Macromolecules are sometimes also called polymers.

• An individual unit of a polymer is called a “monomer”. Lets just say the monomer was one bead of the necklace. A group of many monomers stringed together will form a “Macromolecule”.

• And obviously, different macromolecules will be built out of different units.

MACROMOLECULES

• 1 Describe the formation of poly(ethene) as an example of addition polymerisation of monomer units.

• 2 Draw the structure of poly(ethene).• 3 Describe the formation of a simple condensation

polymer exemplified by nylon, the structure of nylon being represented as:

14.6 SYNTHETIC POLYMERS

A polymer is a substance that contains large molecules formed by many small molecules added together.

Let’s take ethene as an example

A polymer that is made from ethene is called “Poly-ethene”. Poly- basically just means many. We often call this reaction Polymerisation, or polymerization if you’re American.

In a polymerization reaction, what essentially happens is that thousands or smaller molecules join to form a

macromolecule. We call these small molecules monomers.

FORMATION OF POLY(ETHENE)

POLYETHENE

• Double bonds break, which allows monomers molecules to ultimately join together. However, in condensation polymer, no double bonds break. Alternatively:

• Two different monomers join.• The monomers join at their function groups by eliminating small

molecules.• Go on google and find the structure of Diaminohexane and

Hexan-1,6 Dioyl Chloride.• Now, lets call them A and B respectively.• A has an NH2 group at each end. B has a COCl group at each end.

Only these parts, called functional groups take part in the reaction.

• The nitrogen atom at one end of “A” has joined to the carbon atom at one end of B, by eliminating a molecule of hydrogen chloride.

• This continues at the other ends of A and B

CONDENSATION POLYMER

• 1 Describe proteins as possessing the same (amide) linkages as nylon but formed from the linking of amino acids.

• 2 State that proteins can be hydrolysed to amino acids under acid or alkaline conditions. (Structures and names are not required.)

14.7 NATURAL MACROMOLECULES

Proteins are polymers formed from amino acids.

Amino Acids Form

Firstly, protein consists of the elements:

Carbon

Nitrogen

Sulphur

Hydrogen

Oxygen

PROTEINS

The OH and H make a water molecule which is then “eliminated”

Step 1

Just like nylon, we have amide linkage in the place I circled above, but this time it is composed of amino acids.

Step 2

State: Proteins can be hydrolysed to amino acids under acid or alkaline conditions.

Hydrolysis is basically just a process where molecules are broken down upon reaction with water.