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  • 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...
  • 21 May 2024
    Austin Dwyer
    R1.1 Measuring energy changes
    Hi Geoff,Interesting read, thanks!  A couple of thoughts:1. I've always found the enthalpy/energy distinction a little tricky at this stage.  I try to discuss the constant pressure distinction and how it relate to whether or not additional...
  • 20 May 2024
    Geoffrey Neuss
    Rates of reaction questions
    Hello Ivan, The question you are referring to looks to be Question 16 on SL N22P1 and Question 18 on the corresponding HL paper. The first three data points form a straight line in which the concentration has decreased from 1.6 to 1.2 mol dm-3...