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A-Level ChemistryYear 2021Q8

Turn over 15 8 This question is about a dicarboxylic acid Y which is present in some citrus fruits. Y contains only the elements carbon, hydrogen and oxygen. (a) A sample of Y with a mass of 1.98 g was burned completely in excess oxygen. The reaction formed 2.51 g of carbon dioxide, CO2 , and 0.69 g of water, H2O. Use these data to calculate the empirical formula of Y. (4) 16 (b) A solution was prepared using 4.34 g of the dicarboxylic acid Y made up to a volume of 250 cm3 with distilled water. A 25.0 cm3 sample of this solution was then titrated using sodium hydroxide solution, NaOH(aq), of concentration 0.320 mol dm−3. The mean titre of sodium hydroxide solution was 26.10 cm3. Calculate the molar mass of Y using the titration data, and hence deduce its structure. You must show your working. (5) (c) Which of these is used to convert a dicarboxylic acid into a diol? (1) A LiAlH4 and ether B KMnO4 and H2SO4 C Sn and HCl D Na2Cr2O7 and H2SO4 (Total for Question 8 = 10 marks)

Paper Source:9CH0_02_que_20211013.pdf

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Exam Specification Info

This question is part of the UK A-Level Chemistry syllabus. In the actual exam, structured questions typically require linking specific keywords to gain full marks. Applaa helps you drill these topics.

Syllabus levelAdvanced Level (A-Level)
SubjectChemistry
Official MarksVariable (2–6 marks)
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