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  • 21 May 2024
    Geoffrey Neuss
    Major changes for the 2023 programme
    Yes, Andrew - you are correct. A mole is an SI base unit and is defined as exactly 6.02214076 × 1023 elementary entities . In the Guide under S1.4.1 it states "One mole contains exactly the number of elementary entities given by the Avogadro...
  • "This is based on the fact that the atomic mass of the isotope of 12C is exactly 12 so all atomic masses are relative to 1/12 of the mass of one mole of 12C." This was true until they redefined the mole in 2019. Sadly the molar mass constant...
  • 21 May 2024
    Geoffrey Neuss
    R1.1 Measuring energy changes
    Thank you for the feedback and comments Austin. It is true that the definition of standard enthalpy of combustion refers to one mole of the compound so the units of the value should just be kJ. However, there is no command term "define" in...
  • 21 May 2024
    Austin Dwyer
    S2.4 From models to materials
    Probably my favourite part of teaching electronegativity is discussing with students the fact that it is a completely man-made scale.  It correlates with observable physical quantities such as ionisation energies, but does not itself correspond...