A-Level ChemistryYear 2020Q3
8 3 This question is about the compound potassium bromate, KBrO3 . (a) These bromate ions react with bromide ions in acidic solution. BrO3 −(aq) + 5Br−(aq) + 6H+(aq) → 3Br2(aq) + 3H2O(l) (i) Explain, in terms of oxidation numbers, whether or not this is a disproportionation reaction. (2) ..................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... ...................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... (ii) What is the overall order of this reaction? (1) A 3 B 6 C 12 D cannot tell from this information 9 Turn over (b) Potassium bromate decomposes on heating. 2KBrO3 → 2KBr + 3O2 Calculate the maximum volume of oxygen, in dm3, measured at room temperature and pressure (r.t.p.), that could be produced from the complete decomposition of 5.20 g of potassium bromate. [Molar volume of gas at r.t.p. = 24.0 dm3 mol−1] (3) (Total for Question 3 = 6 marks)
Paper Source:9CH0_02_que_20201014.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)