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I taught chemistry for 25 years. I now provide tuition online. I just like nicely produced, imaginative resources.

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I taught chemistry for 25 years. I now provide tuition online. I just like nicely produced, imaginative resources.
NMR examples explained: comparing two esters.
simondobbssimondobbs

NMR examples explained: comparing two esters.

(0)
I came across an exam question which asked the student to identify an ester from two apparently very similar structures and a proton NMR spectrum. This is my attempt to explain the spectra pictorially. I will bundle it with my other ‘NMR examples explained’ series. (NB, I used spectra from a database. The original question shows an expansion of the multiplet peak due to methyl groups as a heptet, ie seven peaks, due to six protons, although this appears to be simulated. The methyl groups appear to be chemically equivalent to me so the multiplet should be a quartet, due to three protons, but I cannot tell from the database spectra. I have stuck with the exam board interpretation and mark scheme. The question is OCR A F324 Wednesday 27 January 2010 question 4)
Ions
simondobbssimondobbs

Ions

(0)
This is a simple powerpoint giving names and formulae of ions. Knowledge of these can provide a key to understanding chemistry at GCSE and A level. Print these off, laminate them, and display in a prominent position in a lab. (NB I have corrected the ammonium ion error)
2,2,4-trimethylpentane- an interesting molecule.
simondobbssimondobbs

2,2,4-trimethylpentane- an interesting molecule.

(0)
2,2,4-trimethylpentane, or iso-octane used to feature heavily in the OCR Salters A level chemistry, because it is an important additive to petrol. It has slipped out of the specification, but the examiner must be sitting on many questions that might be recycled to test understanding. This is a simple information sheet that gives answers to a legacy question that one of my students was completing. It aims to answer difficulties with the question in a graphic way. The sheet runs to three pages and examines isomerism.