Chemistry review c10 c14

Mary Rodriguez
CHEMISTRY REVIEW C10-C14

• 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

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 zone
3. Reduction zone of ferrous
oxide
4. Reduction zone of ferric
oxide
5. Pre-heating zone
6. Feed of ore, limestone
and coke
7. Exhaust gases
8. Column of ore, coke and
limestone
9. Removal of slag
10. Tapping of molten pig
iron
11. 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

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 comparison
Mn Mn2+
reacts with acids
smelting
with coke
Zn Zn2+
Cr Cr2+
Fe Fe2+
Cd Cd2+
Co Co2+
Ni Ni2+
Sn Sn2+
Pb Pb2+
H2 H+
included for comparison
Sb Sb3+
may react with some
strongly oxidizing
acids
heat or
physical
extraction
Bi Bi3+
Cu Cu2+
Hg Hg2+
Ag Ag+
Au Au3+

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
1. 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.
1. 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

• 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.

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 + N2
Nitrogen Oxide + Carbon Monoxide → Carbon Dioxide + Nitrogen
2NO2 + 4CO → 4CO2 + N2
Nitrogen 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

• 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

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

• 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

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 —> Ethanol
C2H4 + 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)

• 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.

Chemistry review c10 c14

Chemistry review c10 c14

Recomendados

Mais conteúdo relacionado

Mais procurados

Mais procurados(20)

Destaque

Destaque(6)

Similar a Chemistry review c10 c14

Similar a Chemistry review c10 c14(20)

Último

Último(20)

Chemistry review c10 c14