Updated version of the 2014 Guide

Tuesday 17 March 2015

Almost exactly one year after the new Chemistry 2014 Guide was published (for first assessment in 2016) an updated version has just appeared on the OCC.

This updated version is dated February 2015 and has several changes. What seems a little odd is that it does not appear to have been flagged on the OCC or, as yet, elicited any comments in the discussion forum. Some, but not all, of the changes are listed in the latest edition (March 2015) of the IB coordinator's notes.

Although there are no major changes it does seem to be a considerable improvement. Many of the ‘typos’ have been corrected so that for example all the ΔHs now have the H in italics and the equation ΔG = − RT lnK in sub-topic 17.1 now has the standard sign next to the ΔG. Equally pleasing is that some of the misinformation has been corrected. In sub-topic 1.3 Lavoisier is no longer stated to be the person who discovered oxygen and the statement in Option A4 on liquid crystals “Friedrich Reinitzer accidently discovered flowing liquid crystals in 1888 while experimenting on cholesterol has now been sort of corrected to “…whilst experimenting on cholesterol (sic) benzoate”. In fact it was cholesteryl benzoate, not cholesterol benzoate. Gone too is the statement in 18.3 referring to the acidity of hydrated transition metal ions - this is definitely not on the new programme. The new guide also clarifies the solvent conditions for SN1 and SN2 reactions. “SN2 reactions are best conducted using aprotic, polar solvents and SN1 reactions are best conducted using protic polar solvents". The word 'peak' is no longer used when describing 1H NMR spectra - it has been replaced by the word 'signal.'

Unfortunately, not all the misinformation has been corrected in this updated version. For example, it still infers in the Nature of Science statement in sub-topic 8.3 that the pH scale is an example of Occam’s razor. In fact it is nothing or the sort. It is just a way of expressing the hydrogen ion concentration in solution in logarithmic form. At least one new error has crept in that was not there before. In sub-topic 1.3 : Reacting masses and volumes the equation PV = nRT has lost the PV so now it is just = nRT. (Thanks to Rebecca Bechard from the United Nations International School of Hanoi who alerted me to this). I know from writing this website that chemistry is fiendishly difficult to write with absolutely no mistakes so my sympathies go out to whoever was responsible for the updated version – will it be corrected before too long?

Tags: Chemistry guide, Lavoisier, Reinitzer, cholesteryl benzoate


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