C6.1 Improving processes and products
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C6.1a explain, using the position of carbon in the reactivity series, the principles of industrial processes used to extract metals, including extraction of a non-ferrous metal
C6.1b explain why and how electrolysis is used to extract some metals from their ores
C6.1c evaluate alternative biological methods of metal extraction to include bacterial and phytoextraction
C6.1d describe the basic principles in carrying out a life-cycle assessment of a material or product
C6.1e interpret data from a life-cycle assessment of a material or product
C6.1f describe a process where a material or product is recycled for a different use, and explain why this is viable
C6.1g evaluate factors that affect decisions on recycling
C6.2h describe the separation of crude oil by fractional distillation to include the names of the fractions
C6.1i explain the separation of crude oil by fractional distillation to include molecular size and intermolecular forces
C6.1j describe the fractions as largely a mixture of compounds of formula CnHn+2 which are members of the alkane homologous series
C6.1k recall that crude oil is a main source of hydrocarbons and is a feedstock for the petrochemical industry
C6.1l explain how modern life is crucially dependent upon hydrocarbons and recognise that crude oil is a finite resource
C6.1m describe the production of materials that are more useful by cracking to include conditions and reasons for cracking and some of the useful materials produced
In topics 6.1a-6.1c, learners will be looking at the reactivity series, and how this series relates to how metals are extracted from their ores. They will also be looking at alternative methods to how metals are extracted such as phytomining.
In this section there are some areas of difficulty that should have attention paid to. Learners are often introduced to carbon reduction via the blast furnace and the extraction of iron. Due to this there is often difficulty in relating this process to the reduction of other metals that are above carbon in the reactivity series, but are not extracted via electrolysis. Ensure there is clarity in this, and that the blast furnace is merely an example. When explaining this also, terms such as oxidation and reduction may be new to the learners. Due to this ensure learners are clear as to the meaning of these terms with regards to the loss and gain of electrons, and that oxidation does not need the presence of oxygen.
In topics 6.1d-g, learners will be tasked with making life-cycle assessments of material.
In topics 6.2h-m learners will be looking at crude oil, and how it is separated into its fractions. Learners are generally able to explain the process of fractional distillation but they often lack clarity in their answer. For example, when asked to describe the process of fractional distillation, learners often miss out that the oil when heated, vaporises, and then condenses when it cools down further up the column. Also, learners often forget to link the change in boiling point to the length of the hydrocarbon chain.
In this topic, learners must be reminded of the uses for crude oil, and that it is not just used as a fuel source, but also as a valuable product in the petrochemical industry. When explaining cracking to learners, it can be useful to refer back to previous work on polymerisation to show the similarity of the two processes. An explanation that cracking is useful because it can provide the alkenes for addition polymerisation can help link the two topics.
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