Four identical sealed containers are prepared each containing \({\text{10 c}}{{\text{m}}^{\text{3}}}\) of an organic compound and at the temperature shown below. Which container will have the highest vapour pressure?

D

In this question, candidates were asked to identify the container with the highest vapour pressure from a list of two substances and related temperatures. One of the substances was \({\text{C}}{{\text{H}}_{\text{3}}}{\text{OC}}{{\text{H}}_{\text{3}}}\), methoxymethane. One respondent stated that ethers are off-syllabus. This is an important point that has been addressed before in a number of subject reports. It is true to say that in the current programme candidates are not required to either identify ethers as a formal functional group or to name them, applying IUPAC rules. However, it should be noted that ethers are referred to in the TN corresponding to AS 4.3.2 in relation to the difference in boiling point between ethanol and methoxymethane, with regard to hydrogen bonding considerations. Hence, it is perfectly valid for methoxymethane to be cited in this particular question on vapour pressure.