04/19/23

Carbon ChemistryCarbon Chemistry

OCR Gateway

W Richards

Fundamental concepts

Compounds

Compounds are formed when two or more elements are chemically combined. Some examples:

Glucose

Methane

Sodium chloride (salt)

Some simple compounds…

Methane, CH4 Water, H2O

Carbon dioxide, CO2

Ethyne, C2H2Sulphuric

acid, H2SO4

Key

Hydrogen

Oxygen

Carbon

Sulphur

More simple compounds…Water

Carbon dioxide

Carbon monoxide

Sulfur dioxide

Sodium hydrogencarbonate

Sodium carbonate

SO2

H2O

NaHCO3

CO2

Na2CO3

CO

Chemical formulaeThe chemical formulae of a molecule or compound is simply a way of showing the ratio of atoms in it. For example…

Na

Cl = sodium chloride (NaCl)

K I = potassium iodide (KI)

K N

O

O

O

= potassium nitrate (KNO3)

Chemical formulae

Try drawing these:

1) Water H2O

2) Carbon dioxide CO2

3) Calcium sulphate CaSO4

4) Magnesium hydroxide Mg(OH)2

Simple chemical reactions

Mg OH Cl

Mg ClCl

HH OH Cl

Magnesium

+ Copper sulphate

Mg

O

OCu

O

O S Cu Mg

O

O

O

O S

Magnesium

sulphate

Copper +

H2OMgO +

WaterMagnesium oxide

+ Hydrochloric acid

Magnesium chloride

+

2HCl MgCl2 +

MgSO4Mg + CuSO4 Cu +

Naming compoundsRule 1– If two identical elements combine then the

name doesn’t change

This happens with the following elements:

1) H2

2) N2

3) O2

4) F2

5) Cl2

6) Br2

These elements always go around in pairs (diatomic molecules). For example, hydrogen looks like this:

Naming compoundsRule 2 – When two elements join and one is a

halogen, oxygen or sulphur the name ends with ____ide

e.g. Magnesium + oxygen magnesium oxide

1) Sodium + chlorine

2) Magnesium + fluorine

3) Lithium + iodine

4) Chlorine + copper

5) Oxygen + iron

6) KBr

7) LiCl

8) CaO

9) MgS

10)KF

Naming compoundsRule 3 – When three or more elements combine and two of them are hydrogen and oxygen the name ends

with hydroxide

e.g. Sodium + hydrogen + oxygen Sodium hydroxide

1) Potassium + hydrogen + oxygen

2) Lithium + hydrogen + oxygen

3) Calcium + hydrogen + oxygen

4) Mg(OH)2

Naming compoundsRule 4 – When three or more elements combine and one of them is oxygen the ending is _____ate

e.g. Copper + sulphur + oxygenCopper sulphate

1) Calcium + carbon + oxygen

2) Potassium + carbon + oxygen

3) Calcium + sulphur + oxygen

4) Magnesium + chlorine + oxygen

5) Calcium + oxygen + nitrogen

6) AgNO3

7) H2SO4

8) K2CO3

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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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The structure of the atomThe structure of the atom

ELECTRON – negative,

mass nearly nothingPROTON –

positive, same mass as neutron

(“1”)

NEUTRON – neutral,

same mass as proton

(“1”)

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 numberMass and atomic number

Particle Relative Mass Relative Charge

Proton 1 +1

Neutron 1 0

Electron Very small -1

MASS NUMBER = number of protons + number of neutrons

SYMBOL

PROTON NUMBER = number of protons (obviously)

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Mass and atomic numberMass and atomic numberHow many protons, neutrons and electrons?

Atoms, ions and moleculesAn “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:

Na

+

Na

Examples of ionic molecules

Mg

Magnesium chloride:

MgCl2

Cl

Cl

+ Mg

2+

Cl

-

Cl

-

Calcium oxide:

CaO

OCa + Ca

2+

O

2-

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Bonding introducedBonding introduced

Hi. My name’s Johnny Chlorine. I’m in Group 7, so I have 7 electrons in my outer

shell

I’d quite like to have a full outer shell. To do this I need to GAIN an electron. Who can

help me?

Cl

Cl

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BondingBondingHere comes one of my friends,

Harry Hydrogen

Hey Johnny. I’ve only got one electron but it’s really close to my nucleus so I don’t want to

lose it. Fancy sharing?

Cl

H

Cl

H

Now we’re both really stable. We’ve formed a covalent bond.

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BondingBondingHere comes another friend,

Sophie Sodium

Hey Johnny. I’m in Group 1 so I have one electron in my outer

shell. Unlike Harry, this electron is far away from the nucleus so I’m

quite happy to get rid of it. Do you want it?

Cl

Now we’ve both got full outer shells and we’ve both gained a charge. We’re both called IONS

and we’ve formed an IONIC bond.

Na

Okay

Cl

Na

+-

C1a – Making Crude Oil useful

FuelsA “fuel” is something that can be burned to release heat and light energy. The main examples are:

Coal, oil and gas are called “fossil fuels”. In other words, they were made from fossils.

04/19/23Hydrocarbons 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 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 water’s boiling point. This method can be used to separate crude oil.

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

Forces between molecules

Weak force of interaction here

Longer molecules = stronger force of attraction

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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 due to the different intermolecular forces between each molecule:

Fractions with low boiling points condense at the top

Fractions with high boiling points condense at the bottom

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Crude OilCrude Oil

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Using Crude OilUsing Crude Oil

Crude Oil

Benefits Drawbacks

Cheap to extract

Wide range of uses as fuel

Used to make plastics

Getting oil from unstable

countries?Burning

fossil fuels causes

pollution

It takes millions of years to

form

It’s going to run out

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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

04/19/23CrackingCracking

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

C1b – Using Carbon Fuels

Choosing a fuel

Does it create pollution?

How much does it cost? Is it easy to use,

store and transport?

Is it toxic?

How much energy does it release?

Which fuel should you use?

Burning Fuels – “Combustion”

Lots of oxygen:

C

H

H

H

HO

O

OO

OH H

OH H

CO

O

Methane Oxygen+ Water+Carbon dioxide

What would a balanced symbol equation for this reaction look like?

Incomplete Combustion

Some oxygen:

Little oxygen:

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

Incomplete combustion is when a fuel is burned without having a plentiful supply of oxygen, e.g. when the Bunsen’s air hole is closed:

Balanced symbol equations?

Incomplete CombustionAs 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”

C1c – Clean Air

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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

04/19/23The Carbon The Carbon CycleCycle

CO2 in air 1. CO2 is taken

in by plants and algae for photosynthesis and turned into carbohydrates, fats and proteins

2. Plants and algae release CO2 through respiration

3. The carbon taken in by plants is then eaten by animals and the animals that eat them

4. Animals release CO2 through respiration

5. Burning fossil fuels also releases 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. Carbon from CO2 becomes locked up in sedimentary rocks as carbonates and fossil fuels. Methane and ammonia react with the oxygen and nitrogen is released.

Population and PollutionThe human population is growing exponentially, particularly in countries like China and India:

Population

Time

This has a number of effects on the environment:

Bigger population means…

Resources – more resources

needed, e.g. deforestation

Farming –less land

available for crops

Waste –more waste needs to be disposed of

Pollution –More phosphates,

nitrates, CO2 and SO2

PollutionWhat causes pollution?

Carbon monoxide is a poisonous gas formed by incomplete combustion.

Sulfur dioxide causes acid rain that kills aquatic life and damages buildings and metals. It’s caused when fuels containing sulfur are burned.

Oxides of nitrogen can cause photochemical smog and acid rain, and are formed in internal combustion engines

Reducing 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

2CO + 2NO N2 + 2CO2

C1d – Making Polymers

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Hydrocarbons revisionHydrocarbons revision

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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AlkanesAlkanesAlkanes 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:

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

04/19/23General Formulae for General Formulae for AlkanesAlkanesInstead of circles, let’s use letters…

General formula for alkanes = CnH2n+2

Butane (n=4)

H

C C

H

HH

H

C C

H

HH

H H

Methane (n=1)

H

C H

H

H

Ethane (n=2)

H

H

C C

H

HH

H

Propane (n=3)

H

C H

H

H

C C

H

HH

H

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AlkenesAlkenesAlkenes are different to alkanes; they contain DOUBLE COVALENT bonds (a bond that has two shared electrons). 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

Testing for alkenesTesting for alkenes04/19/23

Oil Bromine goes colourless

Bromine water This is an

“addition” reaction where the colour change is caused by the formation of a colourless dibromo compound.

04/19/23General Formulae for General Formulae for AlkenesAlkenes

General formula for alkenes = CnH2n

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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Monomers and PolymersMonomers and PolymersC C

HH

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

(this often requires high pressure and a catalyst)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 H

HCH3

Ethene –

polyethene

Vinylchloride –

Polyvinylchloride (PVC)

Propene –

PolypropeneC Cn

H H

HCH3

C1e – Designer Polymers

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

Poly(chloroethene), PVC

Poly(styrene)

What properties would these

polymers have?

Structure of Plastics1) 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

Outdoor Clothing

I love doing outdoor sports. I’d like to wear clothing that is tough but also lets my sweat

out. What should I wear?

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”)

Inner fabric

Gore-tex

Gore-TexGore-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. Here’s how it works:

Outer fabric

Sweat

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.

Disposal 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

Biodegradable carrier bagsBiodegradable carrier bags04/19/23

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

C1f – Cooking and Food Additives

The Chemistry of CookingThe 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”

The Chemistry of CookingNow 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.

Artificial AdditivesWhy 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

E numbers

E100–E199 (colours)

E200–E299 (preservatives)

E300–E399 (antioxidants, acidity regulators)

E400–E499 (thickeners, stabilizers, emulsifiers)

E500–E599 (acidity regulators, anti-caking agents)

E600–E699 (flavour enhancers)

E900–E999 (miscellaneous)

E1000–E1999 (additional chemicals)

If artificial additives are “approved” they are given an E number:

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EmulsionsEmulsionsWhat’s an emulsion?

It’s a mixture of oil and water, like in salad dressing…

Paint is an emulsion. Other examples:

Milk Cream Butter

Butterfat

Watery liquid

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Why use emulsions?Why use emulsions?Emulsions can have varying textures and this makes them useful. Some examples:

Different thicknesses

of cream

Paint and mayonnaise

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EmulsifiersEmulsifiersAn emulsifier is an additive that will stop oil and water from seperating, like in mayonnaise.How they work:

Water Oil

I’m an emulsifier – I’ll sort this out with my hydrophobic end and my hydrophilic end!

I don’t want to mix with you!

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 foodUses of emulsifiers in food

Emulsifiers are used:

1) In bread, to stop large _____ developing when it bakes

2) In low fat spreads, to allow the oil and water to be _____

3) In ice cream and spray cream, to ______ the foam

4) In sponge cakes, to make tiny pockets of ____

5) In chocolate, to stop melted chocolate forming _______

Words – crystals, air, holes, mixed, stabilise

Baking PowderBaking powder is used to make bread rise:

Sodium hydrogen carbonate sodium carbonate + water + carbon dioxide

NaHCO3(s) Na2CO3(s) + H20(g) + CO2(g)2

Gas

Limewater turns milky/cloudy

LimewaterTesting for carbon dioxide:

C1g – Smells

PerfumesPerfumes 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 don’t react with water

A typical perfume reaction:

Ethanol + ethanoic acid ethyl ethanoate + water

C2H5OH + CH3COOH C2H5OOCCH3 + H2O

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

Solubility words

Solute

Solution

Solvent

Soluble

Insoluble

Saturate

d

Solubilit

y

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 CAN’T 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…

Making a solutionA solution forms because

there are:

1) Weak forces of attraction between solute molecules

2) 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.

CosmeticsI 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?

C1h – Paints and Pigments

PaintPaint 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 area:volume ratio and, as such, they have a large surface tension and are difficult to separate.

“Ingredients” in paint

Function

Solvent Gives the paint its colour

Pigment Sticks the pigment to the surface

Binding medium Thins the paint, making it easier to spread

Water based vs Oil based“Water-based paints”

“Oil-based paints”

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

Thermochromic PaintThermochromic 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.

Here’s a strange use of this paint:

Phosphorescent PaintPhosphorescent 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!