14   6 An ester Q has the molecular formula C8H16O2 . (a) When burned in excess oxygen, 1.879 g of Q formed 4.594 g of carbon dioxide and 1.879 g of water. Show that the empirical formula of Q is C4H8O. (4) (b) Data from the high resolution 1H (proton) NMR spectrum of the ester Q are shown in the table. Chemical shift (δ) / ppm Splitting pattern of peak Relative peak area 2.50 singlet 3 1.56 quartet 4 1.43 singlet 3 0.92 triplet 6 Turn over 15   Part of the structure of Q is shown. Complete the structure of Q. Justify your answer by linking the proton environments in your structure to the relative peak areas and the splitting pattern of the peaks. (7) O O H3C C .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... (Total for Question 6 = 11 marks)