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Quantitative Chemistry | AQA GCSE Chemistry Notes |Topic 3

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  • Ar (Relative atomic mass): the mass number.
  • Mr (Relative formula mass): the mass numbers added up (do not multiply by the big number/ coefficient).
  • Moles = mass/ Mr
  • Percentage yield = (actual moles/ calculated moles) x 100
  • Reasons why percentage yield is less than 100%: not all reactants react fully, some reactants left in container, some products escsape.
  • Atom economy = (Mr of desired product/ Mr of all products) x 100
  • Reasons why atom economy is less than 100%: too many products.
  • Importance of high atom economy: saves money, less waste products, saves energy, better for the environment.
  • Limiting reactant: multiply the moles of another reactant by the molar ratio and see if the number of moles is smaller than it shoiuld be.

Topic 3 Quantitative Chemistry for AQA GCSE Triple Science Chemistry Students Only

  • number of moles = concentration (mol/dm3) x volume (dm3)
  • 1 dm3 = 1000 cm3
  • 1000 mol/dm3 = 1 mol/cm3
  • concentration can also be mass/ volume (g/dm3)

Exam Questions to Practice

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