OCR A Level Chemistry A H432/03 Unified chemistry JUNE 2022

Document Content and Description Below

A Level Chemistry A H432/03 Unified chemistry JUNE 2022 Time allowed: 1 hour 30 minutes INSTRUCTIONS • Use black... ink. You can use an HB pencil, but only for graphs and diagrams. • Write your answer to each question in the space provided. If you need extra space use the lined pages at the end of this booklet. The question numbers must be clearly shown. • Answer all the questions. • Where appropriate, your answer should be supported with working. Marks might be given for using a correct method, even if your answer is wrong. INFORMATION • The total mark for this paper is 70. • The marks for each question are shown in brackets [ ]. • Quality of extended response will be assessed in questions marked with an asterisk (*). • This document has 20 pages. ADVICE • Read each question carefully before you start your answer. © OCR 2022 [601/5255/2] DC (ST/SG) 301078/3 OCR is an exempt Charity Turn over Answer all the questions. 1 These questions are from different areas of chemistry. (a) Ammonia, NH3, and ammonium nitrate, NH4NO3, are compounds of nitrogen. (i) The boiling point of NH3 is –33 °C. The boiling point of NH4NO3 is 210 °C. Explain why there is a large difference in boiling points. ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ...................................................................................................................................... [2] (ii) Two students discuss the oxidation numbers in ammonium nitrate, NH4NO3. One student claims that the two nitrogen atoms have the same oxidation number. The other student disagrees and claims that the nitrogen atoms have different oxidation numbers. Explain with reasons which student is correct. ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ...................................................................................................................................... [1] (b) Brass is an alloy of copper and zinc. The mass spectrum of a sample of brass is shown below. Relative abundance 60 61 62 63 64 65 m/z 66 67 68 69 70 The peaks at m/z = 63 and m/z = 65 are from the 63Cu and 65Cu isotopes of copper. The remaining four peaks are from isotopes of zinc. (i) What are the percentage compositions of copper and zinc in the brass sample? Cu = ............. % Zn = % [1] (ii) Calculate the relative atomic mass of zinc in the sample of brass. Give your answer to 2 decimal places. relative atomic mass = [Show More]

Last updated: 11 months ago

Preview 1 out of 26 pages