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neurologyYou need to know

• Crude oil is formed over millions of years from the buried remains of plankton and other marine organisms that were heated and compressed in the absence of oxygen.
• Crude oil is a finite fossil fuel and a mixture of many different hydrocarbons, mostly alkanes.
• A hydrocarbon is a compound that contains hydrogen and carbon atoms only.
• Alkanes are saturated hydrocarbons because they contain only carbon-carbon single bonds.
• The general formula of an alkane is 𝐶𝑛⁢𝐻2⁢𝑛+2.
• The first four alkanes are methane 𝐶⁢𝐻4, ethane 𝐶2⁢𝐻6, propane 𝐶3⁢𝐻8, and butane 𝐶4⁢𝐻10.
• As alkane chain length increases, boiling point, viscosity and flammability change: boiling point and viscosity increase, while flammability decreases.
• Fractional distillation separates crude oil into fractions because hydrocarbons with different chain lengths have different boiling points.
• In fractional distillation, crude oil is vaporised and hydrocarbons condense at different heights in the fractionating column, with smaller molecules condensing near the cooler top and larger molecules condensing near the hotter bottom.
• Common crude oil fractions include refinery gases for heating and cooking, petrol for cars, kerosene for aircraft fuel, diesel for vehicles, fuel oil for ships and power stations, and bitumen for road surfaces and roofing.
• Complete combustion occurs when a hydrocarbon burns in a plentiful supply of oxygen to produce carbon dioxide and water.
• Incomplete combustion occurs when a hydrocarbon burns in a limited supply of oxygen to produce water and carbon monoxide and/or carbon.
• Carbon dioxide turns limewater cloudy, and water can be detected because it turns anhydrous copper sulfate from white to blue or cobalt chloride paper from blue to pink.
• Cracking is the thermal decomposition of long-chain hydrocarbons into shorter alkanes and alkenes.
• Catalytic cracking uses a hot catalyst, such as aluminium oxide or silica, to break long-chain hydrocarbons into smaller molecules.
• Steam cracking uses high temperature and steam to break long-chain hydrocarbons into smaller molecules.
• Alkenes are unsaturated hydrocarbons because they contain at least one carbon-carbon double bond, which makes them more reactive than alkanes.
• The first three alkenes are ethene 𝐶2⁢𝐻4, propene 𝐶3⁢𝐻6, and butene 𝐶4⁢𝐻8, and alkenes with one double bond have the general formula 𝐶𝑛⁢𝐻2⁢𝑛.
• Bromine water tests for unsaturation: alkenes decolourise bromine water from orange to colourless, while alkanes do not react under normal conditions.
• Carboxylic acids contain the functional group 𝐶⁢𝑂⁢𝑂⁢𝐻, are weak acids, and react with metals to form salts and hydrogen, with bases to form salts and water, and with carbonates to form salts, water and carbon dioxide

• Draw and name the displayed and molecular formulae of methane, ethane, propane, butane, ethene, propene and butene, showing single or double carbon-carbon bonds correctly.
• Explain trends in boiling point, viscosity and flammability of hydrocarbons using chain length, intermolecular forces and ease of ignition.
• Describe fractional distillation of crude oil in the correct sequence, including vaporisation, the temperature gradient, condensation and collection of fractions.
• Write balanced symbol equations for complete and incomplete combustion of hydrocarbons, ensuring atoms are conserved on both sides.
• Calculate reacting masses for combustion reactions using the balanced equation, relative formula masses and the mole ratio from the equation.
• Write balanced cracking equations by splitting a long-chain alkane into a shorter alkane and an alkene while conserving atoms.
• Use bromine water to distinguish saturated from unsaturated hydrocarbons, identifying a positive test as a colour change from orange to colourless.
• Predict and write addition reaction equations for alkenes reacting with hydrogen, halogens or steam, showing the double bond opening to form one product.
• Draw repeating units for addition polymers from alkene monomers, and identify the monomer from a given polymer repeating unit.
• Describe condensation reactions that form esters, peptides or biological polymers by identifying the reacting functional groups and the small molecule eliminated.