O-LevelChemistryOrganic Chemistry5070/21 · May/June 2016 · Q37 Marks

Esters, such as propyl ethanoate, are often used as solvents.

(a)Give one other use for esters such as propyl ethanoate.[1]
(b)Draw the structure of propyl ethanoate, showing all of the atoms and all of the bonds.[1]
(c)(i)A bottle of propyl ethanoate is opened in a room. Some of the propyl ethanoate evaporates and then diffuses into the room. What is meant by the term diffusion?[1]
(c)(ii)What happens to the rate of diffusion of propyl ethanoate as the temperature of the room increases? Explain your answer in terms of the kinetic particle theory.[2]
(c)(iii)The table shows some information about different esters. | name | structure | relative molecular mass (Mr) | |---|---|---| | methyl methanoate | HCO2CH3 | 60 | | ethyl methanoate | HCO2C2H5 | 74 | | propyl methanoate | HCO2C3H7 | 88 | | butyl methanoate | HCO2C4H9 | 102 | | pentyl methanoate | HCO2C5H11 | 116 | Which ester has the greatest rate of diffusion at room temperature and pressure? Explain your answer.[2]

Mark scheme

Marking points from the official mark scheme (May/June 2016). The mark or mark type is shown in brackets.

[1] Flavouring (1)
[1] Diagram showing H-C-C(=O)-O-C-C-C-H with all bonds correct (1)
[1] (Net) movement of a substance from a region of high concentration to low concentration (1)
[2] Rate of diffusion increases (1) Particles have more energy/particles are moving faster (1)
[2] Methyl methanoate/HCO2CH3 (1) Lowest relative formula mass (1)

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