Organic (Year 1)

1. Crude oil is heated and vaporised.
2. Fractions have different boiling points.
3. Boiling point depends on size, where shorter hydrocarbons have lower boiling points.
4. There is a temperature gradient where it is hotter at the bottom.
5. Higher boiling point fractions condense nearer the bottom.
6. As a higher boiling point means they liquify more quickly from gas.

1. The carbons cannot rotate about the C=C.
2. Each carbon in the C=C has two different groups attached to it.

1. For the right-hand C in the C=C bond, atom X has a higher atomic number than atom Y, meaning group X takes priority.Note: make sure you refer to ‘atomic number’.
2. For the left-hand C in the C=C bond, atom A has a higher atomic number than atom B, meaning group A takes priority.Note: if the two atoms bonded to one of the Cs in the C=C bond, consider the atoms one bond further away.
3. The highest priority groups, X and A, are on the same side of the C=C bond so it is a Z isomer.

1. They have the same general formula, where successive members differ by CH₂.
2. They have the same functional group.
3. They are chemically similar, so react in (pretty much) the same way.
4. They exhibit a trend in physical properties e.g. increasing boiling point going down the series.

1. Compounds with the same molecular and structural formula.
2. But a different spatial arrangement of atoms.

1. Compounds with the same molecular formula.
2. But different structural formulae.

1. They form when oxygen and nitrogen from the air.
2. React at high temperatures.

1. Acid rain.Note: this damages buildings and ecology.
2. It causes respiratory problems.

1. Acid rain.
2. Respiratory issuesNote: same as SO₂.

1. Usually further substitution of the desired product occurs.
2. Substitution can occur in different positions to the position required for the desired product.
3. Radicals can combine to form long chain products.

1. Thermal occurs at a higher temperature.
2. Thermal occurs at a higher pressure.
3. Catalytic uses a zeolite catalyst.
4. Thermal produces a high percentage of alkenes, whereas catalytic produces a high percentage of motor fuels and aromatics (alongside the shorter chain alkanes)

1. Bond enthalpy. This is the most important factor and decreases going down group 7, where a C-I bond requires less energy to break than a C-Cl bond, meaning iodoalkanes are more reactive than chloroalkanes.
2. Bond polarity. This also plays a role as it means the carbon has a greater positive charge, meaning the lone pair on the nucleophile is more attracted to it, but it is less influential than bond enthalpy so is trumped.

1. Ethanol would form in water as the hydroxide ions would act as a nucleophile.
2. Bromoethane is insoluble in water.

1. The molecules have polar bonds, which absorb infrared radiation and then vibrate.Note: always name the polar bond, e.g. C-Cl.
2. This means the infrared radiation emitted by the Earth does not escape from the atmosphere, as the energy is transferred to other molecules in the atmosphere by collisions.Note: this explanation also applies to greenhouse gases like CO₂.Note 2: not all mark schemes mention the second point, but always include it.

1. There was a lack of evidence that ozone was being depleted.
2. There was a lack of alternatives to CFCs.
3. There was a commercial interest to continue use CFCs.
4. It was hard to obtain international agreement on a ban.

1. The halogen is more electronegative than the carbon it is bonded to, forming a polar bond.
2. This makes the carbon partially positive, causing it to attract the lone pair on the nucleophile.
3. The nucleophile then donates the lone pair to the partially positive carbon.

1. The C=C double bond is an area of high electron density.
2. This polarises the Br₂.
3. The delta positive Br is attracted to the double bond.

1. It is formed from a secondary/ tertiary carbocation.
2. This is more stable than the primary/ secondary carbocation.Note: sometimes it will be tertiary vs. secondary, usually it will be secondary vs. primary.
3. Due to the greater inductive effect from more C groups surrounding the C⁺.

1. Excess ethene.
2. 60 atm (6000kPa) pressure.
3. 300 degrees C.
4. Concentrated phosphoric acid catalyst.

1. The yield is very low.
2. The rate of reaction is very slow.
3. The haloalkane is expensive.

1. No net emissions of CO₂.
2. To the atmosphere.Note: you have to talk about emissions and CO₂ (not carbon) and the atmosphere.

1. When the H⁺ is lost from the C adjacent to the C⁺ to which the -OH was originally attached,Note: remember to always describe the part of the mechanism that results in the isomers in detail.
2. It can either be lost from 1C to form but-1-ene.
3. Or 3C to form but-2-ene.
4. But-2-ene then forms a mixture of E-Z isomers.Note: I'd also add ‘because the C=C bond cannot be rotated’.

1. The thermometer in a bung.
2. Conical flask/ test tube in a beaker of ice for the collection of the liquid.
3. Pear shaped flask connected to the glassware with a clamp.
4. Water cooled condenserNote: make sure you mention where the water goes in and out.
5. Heat with arrow pointed up at the bottom of the pear shaped flask.
6. Antibumping granules and labelled reactants in the pear shaped flask.

1. A label of the reactants that are involved.
2. Heat source.Note: you probably don’t need to actually draw it, just label ‘heat’.
3. Flask with a vertical water condenser.Note: label water in and water out.
4. No gaps in the apparatus, apart from the top where it must be open.

1. Sealing the system, e.g. by adding a bung.Note: the top should be open.
2. Adding a thermometer when it isn’t needed.
3. Not adding antibumping granules.
4. Entering water from the top of the condenser when.Note: it should enter from the bottom.

To test for the presence of ethanal:

1. Add Tollen’s reagent.
2. Warm (often forgotten - was its own mark in this case).
3. Silver mirror is formed.

1. A mixture of liquids is heated to boiling point for a prolonged time.Note: I’d say mentioning it is a ‘mixture’, the fact they reach ‘boiling point’ and it occurs for a ‘prolonged time’ is important.
2. Vapour is formed which escapes from the liquid mixture, is changed back into liquid and returned to the liquid mixture.Note: I would also mention that it is the cooling from the water in the vertical condenser that does this.
3. Any ethanal and ethanol that initially evaporates (as the boiling point is below the activation energy) can then be oxidised.

1. They provide a surface area for small bubbles to form on.
2. This prevents vigorous boiling (bumping) from occurring, which can cause liquid to spill over or blow the equipment apart.Note: if they aren’t labelled as ‘anti-bumping granules’ you can say they ‘prevent bumping’.

1. Add sodium carbonate/ sodium hydrogen carbonate. If a carboxylic acid is present, the solution will fizz and the gas (carbon dioxide) will turn limewater cloudy when bubble through it.Note: make sure you say the full reagent, not just 'carbonate ions'.
2. Add magnesium. If a carboxylic acid is present, the solution will fizz and the gas (hydrogen) will cause a pop to be heard when exposed to a lit splint.
3. Warm with ethanol and a few drops of concentrated sulphuric acid. If a carboxylic acid is present, a sweet smell (from an ester) will be produced.Note: this is the most obscure of the methods - I wouldn’t use unless necessary.

1. Warm with Tollens reagent (ammonia + silver nitrate). Aldehydes will form a silver mirror, but solutions containing ketones will remain colourless.
2. Warm with Fehling's solution. Aldehydes will form a brick-red precipitate, but solutions containing ketones will remain blue.Note: make sure you reference the ‘warm’ part.

1. The fact it oxidises the alcohol.
2. The fact it is acidifiedNote: the acid is needed to provide H⁺ ions for the reduction of the dichromate ions.