Carbon compounds as fuels and feedstock study guide

Carbon compounds as fuels and feedstock

This AQA GCSE Chemistry 8462 Unit 4.7 Organic chemistry guide focuses on Carbon compounds as fuels and feedstock. It is built from approved learning objectives in Organic chemistry and keeps formulae, reactions, properties, and organic families separate.

What this topic covers

• Crude oil, hydrocarbons and alkanes: 10 approved learning objectives.
• Fractional distillation and petrochemicals: 7 approved learning objectives.
• Properties and combustion of hydrocarbons: 9 approved learning objectives.
• Cracking and alkenes: 11 approved learning objectives.

Core revision points

• State that most of the compounds in crude oil are hydrocarbons. In exam answers, connect this point to Crude oil, hydrocarbons and alkanes and use precise organic chemistry language.
• Use molecular modelling kits to make models of alkane molecules. (WS 1.2) In exam answers, connect this point to Crude oil, hydrocarbons and alkanes and use precise organic chemistry language.
• Describe crude oil as a finite resource found in rocks. In exam answers, connect this point to Crude oil, hydrocarbons and alkanes and use precise organic chemistry language.
• Explain that crude oil is the remains of an ancient biomass consisting mainly of plankton buried in mud. In exam answers, connect this point to Crude oil, hydrocarbons and alkanes and use precise organic chemistry language.
• Describe crude oil as a mixture of a very large number of compounds. In exam answers, connect this point to Crude oil, hydrocarbons and alkanes and use precise organic chemistry language.
• State that most hydrocarbons in crude oil are alkanes. In exam answers, connect this point to Crude oil, hydrocarbons and alkanes and use precise organic chemistry language.
• State the general formula for the homologous series of alkanes as CnH2n+2. In exam answers, connect this point to Crude oil, hydrocarbons and alkanes and use precise organic chemistry language.
• Recall the first four members of the alkanes as methane, ethane, propane and butane. In exam answers, connect this point to Crude oil, hydrocarbons and alkanes and use precise organic chemistry language.
• Represent alkane molecules in displayed, structural and molecular formula forms. In exam answers, connect this point to Crude oil, hydrocarbons and alkanes and use precise organic chemistry language.
• Recognise substances as alkanes from their formulae. In exam answers, connect this point to Crude oil, hydrocarbons and alkanes and use precise organic chemistry language.
• Explain that each fraction contains molecules with a similar number of carbon atoms. In exam answers, connect this point to Fractional distillation and petrochemicals and use precise organic chemistry language.
• Explain that crude oil hydrocarbons may be separated into fractions by fractional distillation. In exam answers, connect this point to Fractional distillation and petrochemicals and use precise organic chemistry language.
• Explain that fractions can be processed to produce fuels and feedstock for the petrochemical industry. In exam answers, connect this point to Fractional distillation and petrochemicals and use precise organic chemistry language.
• Identify common fuels produced from crude oil, such as petrol, diesel oil, kerosene, heavy fuel oil and liquefied petroleum gases. In exam answers, connect this point to Fractional distillation and petrochemicals and use precise organic chemistry language.
• Identify useful materials produced by the petrochemical industry, such as solvents, lubricants, polymers and detergents. In exam answers, connect this point to Fractional distillation and petrochemicals and use precise organic chemistry language.
• Explain that the diversity of carbon compounds comes from carbon atoms forming families of similar compounds. In exam answers, connect this point to Fractional distillation and petrochemicals and use precise organic chemistry language.
• Explain how fractional distillation works in terms of evaporation and condensation. In exam answers, connect this point to Fractional distillation and petrochemicals and use precise organic chemistry language.
• Recall how viscosity changes with increasing molecular size. In exam answers, connect this point to Properties and combustion of hydrocarbons and use precise organic chemistry language.
• Investigate the properties of different hydrocarbons. (WS 1.2, 4.1) In exam answers, connect this point to Properties and combustion of hydrocarbons and use precise organic chemistry language.
• State that complete combustion of a hydrocarbon produces carbon dioxide and water. In exam answers, connect this point to Properties and combustion of hydrocarbons and use precise organic chemistry language.
• State that some properties of hydrocarbons depend on the size of their molecules, including boiling point, viscosity and flammability. In exam answers, connect this point to Properties and combustion of hydrocarbons and use precise organic chemistry language.
• Recall how boiling point changes with increasing molecular size. In exam answers, connect this point to Properties and combustion of hydrocarbons and use precise organic chemistry language.
• Recall how flammability changes with increasing molecular size. In exam answers, connect this point to Properties and combustion of hydrocarbons and use precise organic chemistry language.
• Explain that combustion of hydrocarbon fuels releases energy. In exam answers, connect this point to Properties and combustion of hydrocarbons and use precise organic chemistry language.
• Explain that carbon and hydrogen in hydrocarbon fuels are oxidised during combustion. In exam answers, connect this point to Properties and combustion of hydrocarbons and use precise organic chemistry language.
• Write balanced equations for the complete combustion of hydrocarbons with a given formula. In exam answers, connect this point to Properties and combustion of hydrocarbons and use precise organic chemistry language.
• Balance chemical equations as examples of cracking when given the formulae of the reactants and products. In exam answers, connect this point to Cracking and alkenes and use precise organic chemistry language.
• Explain that hydrocarbons can be cracked to produce smaller, more useful molecules. In exam answers, connect this point to Cracking and alkenes and use precise organic chemistry language.
• Recall the colour change when bromine water reacts with an alkene. In exam answers, connect this point to Cracking and alkenes and use precise organic chemistry language.
• Describe catalytic cracking and steam cracking as methods of cracking. In exam answers, connect this point to Cracking and alkenes and use precise organic chemistry language.
• Describe in general terms the conditions used for catalytic cracking and steam cracking. In exam answers, connect this point to Cracking and alkenes and use precise organic chemistry language.
• State that the products of cracking include alkanes and alkenes. In exam answers, connect this point to Cracking and alkenes and use precise organic chemistry language.
• Explain that alkenes are more reactive than alkanes. In exam answers, connect this point to Cracking and alkenes and use precise organic chemistry language.
• Explain that bromine water is used as a test for alkenes. In exam answers, connect this point to Cracking and alkenes and use precise organic chemistry language.
• Explain that some cracked products are useful as fuels because there is a high demand for fuels with small molecules. In exam answers, connect this point to Cracking and alkenes and use precise organic chemistry language.
• Explain that alkenes are used to produce polymers and as starting materials for the production of many other chemicals. In exam answers, connect this point to Cracking and alkenes and use precise organic chemistry language.
• Give examples to illustrate the usefulness of cracking and explain how modern life depends on the uses of hydrocarbons. In exam answers, connect this point to Cracking and alkenes and use precise organic chemistry language.

Formula and structure checks

Use molecular formulae to show atom counts, structural formulae to show how atoms are arranged, displayed formulae only when a diagram renderer is available, and general formulae such as CnH2n+2 or CnH2n only for the correct homologous series.

Concept boundaries

Keep molecular formula, structural formula, displayed formula, and general formula distinct. Do not confuse alkanes with alkenes, saturated with unsaturated, cracking with combustion, polymers with monomers, or hydrocarbons with oxygen-containing alcohols and carboxylic acids. When formulae are used, preserve the stored notation exactly and explain the GCSE chemistry idea in words rather than using unsupported displayed-formula diagrams.

Key terms

• Hydrocarbon
• Crude Oil
• Alkane
• Molecular modelling kits
• finite resource
• crude oil
• Crude oil
• Biomass
• alkanes
• Homologous series
• Methane
• Molecular Formula
• Fraction
• Fractional Distillation
• Hydrocarbon Fraction
• Feedstock
• Diesel oil
• Petrol
• polymer
• petrochemical
• family of compounds
• homologous series
• Evaporation
• Fractional distillation

Exam practice advice

When answering questions, name the organic family, state the formula type, describe the reaction or property, and then connect the evidence back to the learning objective. If a question asks about cracking, focus on forming smaller hydrocarbons and alkenes; if it asks about combustion, focus on oxidation to carbon dioxide and water. If a question asks about polymers, keep monomers and repeat units distinct.