A polymerization of lactic acid was carried out at 60C. The COOH] was determined for each sample by titrating with ethanolic sodium hydroxide. Based on the structure of lactic acid and data in Table 1, answer the following questions: Satu pempolimeran asid laktik telah dijalankan pada 60C. [COOH) telah ditentukan bagi setiap sampel melalui pentitratan dengan ethanolik natrium hidroksida. Berdasarkan struktur laktik asid dan data di Jadual 1, jawab soalan berikut: 3 CH3CHCOOH OH Lactic acid (asid laktik) Table 11 Jadual 1 Time/Masa (hour(s)jam) [COOH) mol dm 0 3.10 0.5 1.30 1.0 0.83 2.0 0.38 0.14 3.0 (Relative atomic mass/jsim atom relatif. H = 1.0; C = 12.0: 0 = 16.0) (a) Draw the structure of the repeating unit of poly(lactic acid) and calculate the molar mass of the repeat unit (M.). Lukiskan struktur unit ulangan poli(asid laktik) dan kira jisim molar unit ulangan (M.). 121 (b) Determine the extent of reaction, p, after two hours. Tentukan darjah tindak balas, p, selepas dua jam. [2] (c) Calculate the number average of polymerization, Xn and the number average -molecular weights, Mn after 2 hours. Hitung purata nombor pempolimeran, X, dan bilangan berat molekul purata nombor, M., selepas 2 jam. [4] (d) Calculate the average number of structural units in the polymer molecule. Hitung purata nombor unit struktur dalam molekul polimer tersebut. [2]