A sample of canola oil is mainly the unsaturated fat Z\text{Z}Z mixed with a small amount of inert impurity. The unsaturated fat Z\text{Z}Z has the molecular formula C57H102O6\text{C}_{57}\text{H}_{102}\text{O}_6C57H102O6 (Mr=882M_r = 882Mr=882) and contains 4 carbon-carbon double bonds per molecule.
The amount of Z\text{Z}Z is determined using the following procedure:
A suitable target titre for the titration is 32.0 cm3 of 0.020 mol dm-3 Br2(aq)\text{Br}_2(\text{aq})Br2(aq).
Justify why a much smaller target titre would not be appropriate.
Calculate the amount, in moles, of bromine in this target titre.
Calculate a suitable mass of canola oil to transfer to the volumetric flask using your answer to Part 1 and the structure of Z\text{Z}Z. Assume that the canola oil contains 80.0% of Z\text{Z}Z by mass. (If you were unable to calculate the amount of bromine in the target titre, you should assume it is 6.0 × 10-4 mol. This is not the correct amount.)
The canola oil solution is prepared using this method:
Suggest an extra step to ensure that the mass of canola oil in the solution is recorded accurately. Justify your suggestion.
State the reason for inverting the flask several times.
A sample of the canola oil was dissolved in methanol and analysed using electrospray ionisation mass spectrometry. Each molecule gained a hydrogen ion (H+\text{H}^+H+) during ionisation. The spectrum showed a peak for an ion with m/z=253m/z = 253m/z=253 formed from an impurity in the canola oil. This ion was formed from a compound with the empirical formula C5H8O\text{C}_5\text{H}_8\text{O}C5H8O. Deduce the molecular formula of this compound, showing your working.
