5.21 Understand that condensation polymerisation produces a small molecule, such as water, as well as the polymer.

When the two monomers come together, one or more atoms is/are lost. These join together to make a small molecule (i.e. H₂O, CH₃OH (methanol) or HCl). The monomers then join together to make the polymer.

5.20 Understand that some polymers, such as nylon, form by a different process called condensation polymerisation

Condensation polymerisation is a situation in which a polymer is formed, along with a small molecule such as H₂O, HCl or CH₃OH (methanol). 

Nylon is an example:

5.19 Explain that addition polymers are hard to dispose of as their inertness means that they do not easily biodegrade

Addition polymers are unreactive because they are saturated, which means they don't biodegrade easily. Solutions used today include:

• burning (not good, produces cancerous / harmful gases)
• landfills (takes up a lot of useful land and harmful chemicals leak into the soil)
• recycling (good for the environment but uses up energy and isn't always cheapest)

5.18 Describe some uses for polymers, including poly(ethene), poly(propene) and poly(chloroethene)

Poly(ethene)

• plastic bags
• light carrier bags
• plastic bottles

poly(propene)

• crates
• ropes
• thermal undergarments

poly(chloroethene)

• water pipes
• wire insulation

5.17 Deduce the structure of a monomer from the repeat unit of an addition polymer

In the simplest terms possible: take away the two 'floating' / empty bonds at the sides and make a carbon carbon double bond between 2 carbons instead. 

5.16 Draw the repeat unit of addition polymers, including poly(ethene), poly(propene) and poly(chloroethene)

Repeat units must be drawn:

• within large brackets
• with two bonds sticking out of the brackets
• an n at the end, representing the number of times it is repeated (i.e. n could be anything, you don't write the number, write n)

Poly(ethene) and poly(chloroethene):

Poly(propene)

5.15 Understand that an addition polymer is formed by joining up many small molecules called monomers

Exactly what the point says: addition polymers are made by joining up many small ones called monomers: "mono" meaning one and "poly" meaning many

3.8 Describe the addition reaction of alkenes with bromine, including the decolourising of bromine water as a test for alkenes

When an alkene reacts with bromine, it turns one of its double (unsaturated) bonds into a single bond so it can bond with the bromine atoms. For example, ethane (shown below as ethylene) will bond with bromine to form 1,2 dibromoethane. (Br is on molecules 1 and 2, there are 2 of them, and the rest is ethane. That's the naming process aha)

Because of this, Br water will decolorize if you mix an alkane with it. 

It will not decolorize immediately with alkenes because they are saturated.

This is a good way to test for alkenes, since there is always a colour change (bromine water turns from brown to colourless) whenever alkenes are put in it.

Also, to bond to two bromines, the alkene must make its double bond a single bond, hence the name addition reaction

1.55 Write ionic half-equations representing the reactions at the electrodes during electrolysis

At positive (anode) electrode, electrons are lost.
eg 2Br- > Br2 + 2e-

At negative (cathode) electrode, electrons are gained.
eg 2H+ + 2e- > H2

*Make sure charges are the same on both sides!!

1.54 Describe experiments to investigate electrolysis, using inert electrodes, of aqueous solutions such as sodium chloride, copper(II) sulfate and dilute sulfuric acid and predict the products

• Place inert electrodes in aqueous ionic solution
• At positive electrode (anode), - ion will form an atom (non metal) 
• At negative electrode (cathode), + ion will form an atom (metal)

eg

• Sodium chloride: sodium at cathode, chlorine at anode
• Copper(II) sulphate: copper at cathode, oxygen at anode, sulphur stays in solution
• Sulphuric acid: hydrogen at cathode, oxygen at anode, sulphur stays in solution

To help remember:

CINDY IS NOT AN INDECENT POTATO:

Cathode

Is

Negative

Anode

Is

Positive

NAP MAN:

Non-metal

At

Positive

Metal

At

Negative

CCOASS (for copper(II) sulphate)

(Cathy Chopped Apples And Stabbed Sue)

Copper

Cathode

Oxygen

Anode

Sulphur

Solution

HCOASS (for dilute sulphuric acid)

(Henry Cut Onions And Started Sulking)

Hydrogen

Cathode

Oxygen

Anode

Sulphur

Solution

1.53 Describe experiments to investigate electrolysis, using inert electrodes, of molten salts such as lead(II) bromide and predict the products

Figure 1

• Set up the apparatus in figure 1
• The lead (metal) will be attracted to the negative cathode where it will gain electrons
• The bromine (non metal) will be attracted to the positive anode where it will lose electrons
• Lead and bromine formed
• Yay

Inert electrodes don't react with other substances - only play a role in electron transfer and you need to be able to draw that apparatus. Good luck, padawan.

1.52 Understand that electrolysis involves the formation of new substances when ionic compounds conduct electricity

Ionic compounds conduct electricity when molten or in solution. During electrolysis, positively charged ions move to one side (cathode, which is the negatively charged electrode) and form metals. The negatively charged ions move to the other side (anode, the positively charged electrode) to form non metals. This is because opposite charges attract. These ions become atoms / new products because they undergo a reaction where either a gain or loss of electrons occurs.

TO REMEMBER:
Cathode
Is
Negative
Anode
Is
Positive

Cindy Is Not An Indecent Potato

1.51 Describe experiments to distinguish between electrolytes and non-electrolytes

• Set up a circuit with an LED light, a battery/power pack, wire and a solution
• Create a gap between the two ends of the wire. Place them in the solution.
• Switch the power pack on (if required)
• If LED lights up, a current is flowing through the molten substance / solution. This means it is an electrolyte.
• If it doesn't light up, there's no current, therefore it is not an electrolyte.

Or you could just...

1.50 Understand why ionic compounds conduct electricity only when molten or in solution

When in solution, ions separate (to form + and - ions, accordingly) and they become free to move, so they can carry electricity and so the compound can now conduct when it is molten / in solution.

1.49 Understand why covalent compounds do not conduct electricity

In covalent substances, the electrons are not free to move, so current can't move through the substance; there's no electrons to carry it - no transfer of electricity.

1.48 Understand that an electric current is a flow of electrons or ions

Surprise! An electric current is a flow of electrons or ions. Well done, me. 

5.14 describe how long-chain alkanes are converted to alkenes and shorter-chain alkanes by catalytic cracking, using silica or alumina as the catalyst and a temperature in the range of 600–700ºC

Passing long-chain hydrocarbons over a hot catalyst (in this case silica or alumina at roughly 600-700ºC) will cause them to break down into smaller chains of hydrocarbons

Some of the atoms are lost from the molecules, making them unsaturated and able to form a double bond. This is how you can get alkenes from cracking, not just short-chain hydrocarbons

5.13 Understand that fractional distillation of crude oil produces more long-chain hydrocarbons than can be used directly and fewer short-chain hydrocarbons than required and explain why this makes cracking necessary

The main problem is that long-chain hydrocarbons are more viscous and less flammable, whereas the short-chain hydrocarbons flow and burn well, which makes them more useful.

However, as the title said, more long-chain hydrocarbons are produced then short-chain ones.

TADA! We have cracking, which breaks up the longer, less useful hydrocarbons into shorter, more useful hydrocarbon

5.12 Understand that nitrogen oxides and sulfur dioxide are pollutant gases which contribute to acid rain, and describe the problems caused by acid rain

NO (nitrogen oxide) is produced in car engines.

When nitrogen oxide and sulfur dioxide are in the atmosphere they react with rainwater to create H+ ions, making it more acidic. This means that when rain falls it can alter the PH in soil or rivers which will severely affect the ecosystem. It can also corrode limestone, damaging rocks, buildings (a big problem if the buildings are historical ones)

5.11 Understand that, in car engines, the temperature reached is high enough to allow nitrogen and oxygen from air to react, forming nitrogen oxides

Literally what it says in the title.

In car engines, the temperature is high enough for nitrogen and oxygen in the air to react, forming NO

5.10 Understand that incomplete combustion of fuels may produce carbon monoxide and explain that carbon monoxide is poisonous because it reduces the capacity of the blood to carry oxygen

Usually hydrogens combust with oxygen to give carbon dioxide and and water, like so:

• Hydrocarbons + oxygen > carbon dioxide + water

However, if there is not enough oxygen, resulting in an incomplete combustion, the following reaction will be produced:

• Hydrocarbons + oxygen > carbon monoxide + carbon + water

Carbon monoxide is poisonous because it bonds with haemoglobin in the blood instead of oxygen, meaning that the oxygen isn't carried around the body

5.9 Describe the trend in boiling point and viscosity of the main fractions

Fractions with low boiling points are less viscous than fractions with higher boiling points.

5.8 Recall the names and uses of the main fractions obtained from crude oil: refinery gases, gasoline, kerosene, diesel, fuel oil and bitumen

This diagram has all that you need to know :)

5.7 Describe and explain how the industrial process of fractional distillation separates crude oil into fractions

Crude oil is separated into it's various hydrocarbons by fractional distillation, which happens like so:
1. Crude oil is heated
2. As a gas it floats upwards, where the temperature decreases
3. One by one, each compound in the crude oil will reach it's condensing point and condense
4. It will then be collected

This ensures that all groups with similar condensing temperatures (known as fractions) are each separated, since each fraction is a different substance

5.6 Understand that crude oil is a mixture of hydrocarbons

Basically, crude oil is made up of different hydrocarbons (molecules with ONLY hydrogen and carbon atoms in them)

3.12 Describe the dehydration of ethanol to ethene, using aluminium oxide.

• Ethanol > ethene + water
• C2H5OH > C2H4 + H2O

Aluminium oxide is a catalyst in this reaction

3.11 Evaluate the factors relevant to the choice of method used in the manufacture of ethanol, for example the relative availability of sugar cane and crude oil

HYDRATION OF ETHENE

• Pros
• The process is continuous
• Only one product is produced (no need to separate them afterwards)
• Fewer workers are needed
• Fast process
• Cons
• Comes from non-renewable, expensive sources (crude oil, cracked to make ethene)
• High temperature and pressure is needed
• A lot of energy is used

FERMENTATION OF SUGARS

• Pros
• Sugar is a renewable source
• It is also widely available and cheap
• Normal pressure and a warm environment used
• Cons
• Two products are produce (they are impure and need to be purified)
• It is a batch process (stop-start)
• A lot of workers are needed
• It is a slow process

3.10 Describe the manufacture of ethanol by the fermentation of sugars, for example glucose, at a temperature of about 30°C

The (natural) catalyst for this reaction are the enzymes found in single-celled fungi (yeast)

The anaerobic respiration of microorganisms can produce ethanol.

• Glucose > ethanol + carbon dioxide
• C₆6H₁₂O₆ > 2C₂H₅OH + 2CO₂

The reaction also takes place at a temperature of 30°C

The absence of air is required for this reaction, and the products are purified by fractional distillation

3.9 Describe the manufacture of ethanol by passing ethene and steam over a phosphoric acid catalyst at a temperature of about 300°C and a pressure of about 60–70 atm

Ethanol can be made by reacting ethene (from cracking crude oil fractions) with steam (aka the hydration of ethene).

• Ethene + steam > ethanol
• C2H4 + H2O > C2H5OH

Phosphoric acid is a catalyst for this reaction. You also need to remember:
- The pressure (60-70 atm) at which the reaction takes place
- The temperature (300°C)

The process is continuous (as long as there are always reactants)

The high pressure and temperature make the reaction happen really quickly. This is described as the dehydration of ethene (I'm pretty sure)

3.7 Draw displayed formulae for alkenes with up to four carbon atoms in a molecule, and name the straight-chain isomers

This is where it gets difficult. Because all alkenes have a double carbon to carbon bond, when drawing the displayed formula for an alkene you must always remember:
- Carbon only has four bonds
- Therefore, if two of those are to another carbon
- It will only be bonded to two other hydrogens

3.6 Recall that alkenes have the general formula CnH2n

Basically, all compounds in the homologous group alkenes have the general formula CnH2n, which means that for every carbon atom there are two hydrogen ones

3.5 Describe the substitution reaction of methane with bromine to form bromomethane in the presence of UV light.

(Taken directly, word for word (because I am extremely lazy right now) from Hannah Help Chemistry)

In UV light bromine and methane will form bromomethane:

CH₄  +  Br₂ >CH₃Br  +  HBr

What has happened in this reaction is a bromine has taken the place of a hydrogen (substitution.)

3.4 Recall the products of the complete and incomplete combustion of alkanes

Complete combustion of alkanes will give you carbon dioxide and water

Incomplete combustion will give you carbon monoxide and water

3.3 Draw displayed formulae for alkanes with up to five carbon atoms in a molecule, and name the straight-chain isomers

All you need to remember when drawing displayed formulas for alkanes is that every carbon is bonded to two hydrogens (usually draw them one on top and one below) and there are two hydrogens on the end of the whole thing.

Below is the displayed formula for
1. Methane


2. Ethane
 

3. Propane


4. Butane


5. Pentane

1.23 Understand how the formulae of simple compounds can be obtained experimentally, including metal oxides, water and salts containing water of crystallisation

• Weigh the compound
• Remove one element of it through a reaction
• Weigh again
• If the first weight [mass] of the compound is AB and the second weight [mass] is A, you can work out B by: AB-A=B
• Work it out by dividing the weight by the relative atomic mass

3.2 Recall that alkanes have the general formula CnH2n+2

If you see the post tagged 3.1, a general formula is a formula that all members of a homologous series (in this case, the alkanes) will fit.

Basically (in every single alkane) for every carbon atom there will be twice the amount of hydrogen plus two.
- E.g.: 2 carbons
-         2(2) + 2 hydrogens = 6 hydrogens

3.1 Explain the terms homologous series, hydrocarbon, saturated, unsaturated, general formula and isomerism.

HOMOLOGOUS SERIES: 
"A homologous series is a family of hydrocarbons with similar chemical properties who share the same general formula" (BBC Bitesize). Basically, compounds (in this case hydrocarbons) in the same homologous series have the SAME general formula and SIMILAR chemical properties

HYDROCARBON
A compounds made up of ONLY hydrogen and carbon atoms

SATURATED 
A compound is described as 'saturated' if it ONLY has single bonds present. This means that the compounds has "bonded as many times as possible" (Hannah Help). 

UNSATURATED
A hydrocarbon with a double carbon carbon bond is described as unsaturated, because more bonds can be made (as can be seen later in polymerisation)

GENERAL FORMULA
A formula that all members of the same homologous series will fit.

ISOMERISM
Compounds with the same chemical formulas, but different structural formulas

2.38 Describe tests for anions

i) USING DILUTE NITRIC ACID & SILVER NITRATE SOLUTION (depending on the precipitate)

• Chloride ions (Cl-) + nitric acid + silver nitrate > white precipitate 
• Precipitate = silver chloride
• Bromide ions + nitric acid + silver nitrate > cream precipitate 
• Precipitate = silver bromide
• Iodide ions + nitric acid + silver nitrate > yellow precipitate 
• Precipitate = silver iodide

ii) USING DILUTE HYDROCHLORIC ACID & BARIUM CHLORIDE SOLUTION

• Sulphate ions + hydrochloric acid + barium chloride > white precipitate
• SO4(2-) + HCl + BaCl2 (2+) > BaSO4
• Precipitate = barium sulphate

iii) USING DILUTE HYDROCHLORIC ACID (& identifying if CO2 is produced)

• Carbonate + hydrochloric acid > salt + water + carbon dioxide
• Test for CO2:
• When bubbled through lime water, will turn it cloudy

2.37 Describe tests for the following cations:

i) FLAME TESTS

• Li+ (Lithium) burns with a red flame
• Na+ (Sodium) burns with a strong orange flame (sometimes it is so strong it can mask other colours)
• K+ (Potassium) lilac flame
• Ca2+ (Calcium) burns with a brick red flame

ii) NH4+ USING SODIUM HYDROXIDE SOLUTION (& identifying the ammonia produced)

• ammonium ions + hydroxide ions > ammonia + water
• (NH4 + OH > NH3 + H2O)
• How to test for ammonia: 
• ammonia will turn red litmus paper blue
• it also has a 'pungent' smell

iii) USING SODIUM HYDROXIDE SOLUTION (CU2+, FE2+, FE3+)

• Copper (ii) sulphate + sodium hydroxide > blue precipitate
• CuSO4 + NaOH
• Iron (ii) sulphate + sodium hydroxide > green precipitate
• FeSO4 + NaOH
• Iron (iii) sulphate + sodium hydroxide > brown precipitate
• Fe2(SO4)3 + NaOH