Choosing a Reaction Pathway (Edexcel GCSE Chemistry)

Revision Note

Stewart Hird

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Choosing a Reaction Pathway

  • Reactions that have low atom economies use up a lot of resources and produce a lot of waste material which then needs to be disposed of, a very expensive procedure

  • These reactions are thus unsustainable as they use up too much raw material to manufacture only a small amount of product

  • They are not economically attractive as raw materials tend to be expensive, as does waste disposal which requires chemicals, equipment, space and transport

  • Companies continually analyse reactions and processes and evaluate several factors in an effort to improve efficiency

  • Atom economy, percentage yield, rates of reaction and equilibrium position are important factors which need to be considered when choosing a reaction pathway

  • High percentage yields and fast reaction rates are desirable attributes in industrial chemical processes

  • In reversible reactions, the position of the equilibrium may need to be changed in favour of the products by altering reaction conditions

  • If the waste products can be sold or reused in some way that would improve the atom economy

  • Alternative methods of production could also be considered that may produce a more useful by-product

Examiner Tips and Tricks

Look for information on percentage yield, atom economy, rate and equilibria in questions on this topic. Your answer should then be based on evaluating (for example by comparing the pros and cons of) this information.

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Stewart Hird

Author: Stewart Hird

Expertise: Chemistry Lead

Stewart has been an enthusiastic GCSE, IGCSE, A Level and IB teacher for more than 30 years in the UK as well as overseas, and has also been an examiner for IB and A Level. As a long-standing Head of Science, Stewart brings a wealth of experience to creating Topic Questions and revision materials for Save My Exams. Stewart specialises in Chemistry, but has also taught Physics and Environmental Systems and Societies.