Carbon Chemistry

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Carbon Chemistry
OCR Gateway
W Richards
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Fundamental concepts
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Compounds
Compounds are formed when two or more elements
are chemically combined. Some examples
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Some simple compounds
Carbon dioxide, CO2
Water, H2O
Ethyne, C2H2
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More simple compounds
Water
SO2
Carbon dioxide
H2O
Carbon monoxide
NaHCO3
Sodium hydrogencarbonate
Na2CO3
Sulfur dioxide
CO2
Sodium carbonate
CO
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Chemical formulae
The chemical formulae of a molecule or compound
is simply a way of showing the ratio of atoms in
it. For example
sodium chloride (NaCl)
potassium iodide (KI)
potassium nitrate (KNO3)
K
N
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Chemical formulae

• Try drawing these
• Water H2O
• Carbon dioxide CO2
• Calcium sulphate CaSO4
• Magnesium hydroxide Mg(OH)2

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Simple chemical reactions
Water
H2O
Magnesium sulphate
MgSO4
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Naming compounds
Rule 1 If two identical elements combine then
the name doesnt change
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Naming compounds
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Naming compounds

1. Potassium hydrogen oxygen
2. Lithium hydrogen oxygen
3. Calcium hydrogen oxygen
4. Mg(OH)2

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Naming compounds
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Balancing equations
Consider the following reaction


This equation doesnt 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 equations
We need to balance the equation


Now the equation is balanced, and we can write it
as
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Some examples
2 2 2 3
2 2 2 2 3
2 2 2 2 2 4
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The structure of the atom
The Ancient Greeks used to believe that
everything was made up of very small particles.
I did some experiments in 1808 that proved this
and called these particles ATOMS
Dalton
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Mass and atomic number
Particle Relative Mass Relative Charge
Proton 1 1
Neutron 1 0
Electron Very small -1
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Mass and atomic number
How many protons, neutrons and electrons?
1
11
16
H
B
O
1
5
8
23
35
238
Na
Cl
U
11
17
92
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Atoms, ions and molecules
An atom is simply one particle on its own in
its normal state, e.g. a helium atom
An ion is an atom that has lost or gained
electrons, e.g. sodium
A molecule is a combination of atoms in a
compound
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Examples of ionic molecules
Magnesium chloride

MgCl2
Calcium oxide
CaO
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Bonding introduced
Hi. My names Johnny Chlorine. Im in Group 7,
so I have 7 electrons in my outer shell







Id quite like to have a full outer shell. To do
this I need to GAIN an electron. Who can help me?
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Bonding
Here comes one of my friends, Harry Hydrogen
Hey Johnny. Ive only got one electron but its
really close to my nucleus so I dont want to
lose it. Fancy sharing?
Now were both really stable. Weve formed a
covalent bond.
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Bonding
Here comes another friend, Sophie Sodium
Hey Johnny. Im in Group 1 so I have one
electron in my outer shell. Unlike Harry, this
electron is far away from the nucleus so Im
quite happy to get rid of it. Do you want it?
Okay
Now weve both got full outer shells and weve
both gained a charge. Were both called IONS and
weve formed an IONIC bond.
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C1a Making Crude Oil useful
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Fuels
A fuel is something that can be burned to
release heat and light energy. The main examples
are
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Hydrocarbons and crude oil
Crude oil is a mixture of HYDROCARBONS (compounds
made up of carbon and hydrogen). Some examples

• Longer chains mean
• Less ability to flow
• Less flammable
• Less volatile
• Higher boiling point

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Distillation revision
This apparatus can be used to separate water and
ethanol because they have different _____ ______.
The ______ will evaporate first, turn back into
a _______ in the condenser and collect in the
_______. The water remains in the round flask,
as long as the _______ does not exceed waters
boiling point. This method can be used to
separate crude oil.
Words temperature, boiling points, ethanol,
beaker, liquid
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Forces between molecules
Weak force of interaction here
Longer molecules stronger force of attraction
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Fractional distillation
Crude oil can be separated by fractional
distillation. The oil is evaporated and the
hydrocarbon chains of different lengths condense
at different temperatures due to the different
intermolecular forces between each molecule
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Crude Oil
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Using Crude Oil
Benefits
Drawbacks
Getting oil from unstable countries?
Cheap to extract
Burning fossil fuels causes pollution
Crude Oil
Wide range of uses as fuel
Used to make plastics
It takes millions of years to form
Its going to run out
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Cracking
Shorter chain hydrocarbons are in greater demand
because they burn easier. They can be made from
long chain hydrocarbons by cracking
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Cracking
This is a THERMAL DECOMPOSITION reaction, with
clay used as a catalyst
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

1. Carbon dioxide causes the _________ effect
2. Sulfur dioxide causes _____ _____
3. Plastics are not _____________

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C1b Using Carbon Fuels
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Choosing a fuel
Which fuel should you use?
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Burning Fuels Combustion
Lots of oxygen
Methane
What would a balanced symbol equation for this
reaction look like?
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Incomplete Combustion
Incomplete combustion is when a fuel is burned
without having a plentiful supply of oxygen, e.g.
when the Bunsens air hole is closed
Some oxygen
Little oxygen
Balanced symbol equations?
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Incomplete Combustion
As well as producing carbon monoxide, incomplete
combustion can also produce soot
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C1c Clean Air
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The Earths Atmosphere
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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The Carbon Cycle
21/11/2013
2. Plants and algae release CO2 through
respiration
1. CO2 is taken in by plants and algae for
photosynthesis and turned into carbohydrates,
fats and proteins
4. Animals release CO2 through respiration
3. The carbon taken in by plants is then eaten by
animals and the animals that eat them
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Evolution of the Earths Atmosphere
Present day atmosphere contains 78 nitrogen, 21
oxygen, 1 noble gases and about 0.03 CO2
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Evolution of the Earths Atmosphere
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.
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Population and Pollution
The human population is growing exponentially,
particularly in countries like China and India
This has a number of effects on the environment
Resources more resources needed, e.g.
deforestation
Farming less land available for crops
Pollution More phosphates, nitrates, CO2 and SO2
Waste more waste needs to be disposed of
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Pollution
What causes pollution?
Sulfur dioxide causes acid rain that kills
aquatic life and damages buildings and metals.
Its caused when fuels containing sulfur are
burned.
Carbon monoxide is a poisonous gas formed by
incomplete combustion.
Oxides of nitrogen can cause photochemical smog
and acid rain, and are formed in internal
combustion engines
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Reducing Pollution from vehicles
A 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!
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C1d Making Polymers
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Hydrocarbons revision
21/11/2013
Crude oil is a mixture of HYDROCARBONS (compounds
made up of carbon and hydrogen). Some examples

• Longer chains mean
• Less ability to flow
• Less flammable
• Less volatile
• Higher boiling point

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Alkanes
Alkanes 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 COVALENT bonds, for example
Alkanes are fairly unreactive (but they do burn
well). The general formula for an alkane is
CnH2n2
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General Formulae for Alkanes
Instead of circles, lets use letters
General formula for alkanes CnH2n2
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Alkenes
Alkenes are different to alkanes they contain
DOUBLE COVALENT bonds (a bond that has two shared
electrons). For example
This double bond means that alkenes have the
potential to join with other molecules this
make them REACTIVE. Alkenes turn bromine water
colourless.
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Testing for alkenes
This is an addition reaction where the colour
change is caused by the formation of a colourless
dibromo compound.
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General Formulae for Alkenes
General formula for alkenes CnH2n
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Monomers and Polymers
Heres 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 (this often
requires high pressure and a catalyst)
Step 2 Add the molecules together
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Another way of drawing it
Instead of circles, lets use letters
General formula for addition polymerisation
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Some examples
Ethene polyethene
Vinylchloride Polyvinylchloride (PVC)
Propene Polypropene
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C1e Designer Polymers
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Uses of addition polymers
Poly(ethene)
Poly(propene)
What properties would these polymers have?
Poly(chloroethene), PVC
Poly(styrene)
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Structure of Plastics
1) Some plastics have ____ intermolecular forces
between each molecule these have __ melting
points and can be ______ easily as the molecules
_____ over each other.
2) Some plastics have _____ forces between each
molecule. These have ____ melting points and are
____.
Words high, low, strong, weak, stretched,
rigid, slide
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Outdoor Clothing
I love doing outdoor sports. Id like to wear
clothing that is tough but also lets my sweat
out. What should I wear?
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Nylon and Gore-Tex
Nylon lightweight, tough, waterproof, blocks UV
Gore-tex nylon coated with PTFE this means
that it can allow perspiration to escape but rain
cannot get in (it can breathe)
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Gore-Tex
Gore-tex is a material made from nylon laminated
with the polymer PTFE and its invention has been
of great use in the world of outdoor sports.
Heres how it works
Basically, the holes in the material are too
small for water drops to pass through but big
enough for sweat vapour. On its own, the
membrane is too fragile so it is combined with
nylon.
Sweat
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Disposal of plastics
Words recycling, greenhouse, decompose,
biodegradable, poisonous
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Biodegradable carrier bags
21/11/2013
This carrier bag has been made with flax fibre
from industrial waste.
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C1f Cooking and Food Additives
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The Chemistry of Cooking
The process of cooking food causes some chemicals
to turn into others (i.e. a chemical change) and
these are irreversible. For example, consider a
protein molecule
Denatured
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The Chemistry of Cooking
Now consider a potato cell
Cooking a potato causes the cell wall to break,
leading to a softer texture. Starch grains also
swell up and spread out.
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Artificial Additives
Why do we use additives?
Some examples
Additive Interesting information
Flavour enhancers Can include traditional ingredients like salt, vinegar etc. Monosodium glutamate is often used in Chinese foods (its found in soy sauce)
Colour enhancers Processing food often results in colour loss so colour enhancers are used. Could be natural like carotenes or artificial like tartrazine
Preservatives Can include vinegar and sugar. Artificial preservatives are used to stop microbes growing and antioxidants stop fats going off
Vitamins and minerals Can be used to replace those lost during cooking
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E numbers
If artificial additives are approved they are
given an E number
E100E199 (colours) E200E299 (preservatives)
E300E399 (antioxidants, acidity regulators)
E400E499 (thickeners, stabilizers, emulsifiers)
E500E599 (acidity regulators, anti-caking
agents) E600E699 (flavour enhancers) E900E999
(miscellaneous) E1000E1999 (additional
chemicals)
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Emulsions
Whats an emulsion?
Its a mixture of oil and water, like in salad
dressing
Paint is an emulsion. Other examples
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Why use emulsions?
Emulsions can have varying textures and this
makes them useful. Some examples
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Emulsifiers
An emulsifier is an additive that will stop oil
and water from seperating, like in mayonnaise.
How they work
Im an emulsifier Ill sort this out with my
hydrophobic end and my hydrophilic end!
I dont want to mix with you!
Water
Oil
The water and oil drops become coated and
insulated from one another, which prevents them
from seperating.
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Uses of emulsifiers in food

• Emulsifiers are used
• In bread, to stop large _____ developing when it
  bakes
• In low fat spreads, to allow the oil and water to
  be _____
• In ice cream and spray cream, to ______ the foam
• In sponge cakes, to make tiny pockets of ____
• In chocolate, to stop melted chocolate forming
  _______

Words crystals, air, holes, mixed, stabilise
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Baking Powder
Baking powder is used to make bread rise
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Testing for carbon dioxide
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C1g Smells
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Perfumes
Perfumes are synthetically made from chemicals
called esters. Here are some facts about
perfumes. Why are these things important?

1. Perfumes are non-toxic
2. They are non-irritants
3. They evaporate easily
4. They do not dissolve in water
5. They dont react with water

A typical perfume reaction
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Solutions revision
If a substance CAN be dissolved it is called
__________ If a substance CANNOT be dissolved it
is called _________
Words soluble, solute, solvent, solution,
insoluble
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Solubility words
Solute Solution Solvent Soluble Insoluble Saturate
d Solubility
Something that CAN dissolve is described as
being How much of something that can be
dissolved is called Something that CANNOT be
dissolved is described as being A solution that
CANT dissolve anything else is The solid that
will be dissolved is the The mixture of solute
and solvent is called the The liquid that the
solute will be dissolved into is the
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Making a solution

• A solution forms because there are
• Weak forces of attraction between solute
  molecules
• Strong forces of attraction between solute and
  solvent molecule

For example, nail varnish remover works because
the nail varnish remover molecules are attracted
to the nail varnish molecules with a stronger
attraction than water molecules are. Esters can
be used as solvents.
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Cosmetics
I think that the testing of cosmetics should be
allowed.
No way! I totally disagree.
The testing of cosmetics on animals is currently
banned in the EU. Who do you agree with and why?
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C1h Paints and Pigments
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Paint
Paint is an example of a colloid a mixture of
one or more substances in a liquid but which are
not dissolved. The molecules have a large
surface areavolume ratio and, as such, they have
a large surface tension and are difficult to
separate.
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Water based vs Oil based
In water-based paints the paint dries when the
_______ evaporates, causing them to dry in around
one ______. In oil-based paints the solvent has
to ________ and then the oil is _______ by oxygen
in the air, which takes longer and paint brushes
have to be cleaned with ____ ___ rather than
water.
Words white spirit, evaporate, water, hour,
oxidised
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Thermochromic Paint
Thermochromic paint is paint that changes colour
when heated. Some uses
Acrylic paints can be added to thermochromic
paint to give it an even wider range of
colours. Heres a strange use of this paint
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Phosphorescent Paint
Phosphorescent paint is paint that contains
pigments that can glow in the dark. They do this
by storing energy and then release it over time
The original glow-in-the-dark paint contained
radioactive materials so this paint is much safer!