TJC_H1_CHEM_P2_(A)_ANS

2015 TJC H1 Chemistry Preliminary Exam s CANDIDATE NAME ANSWERS CIVICS GROUP / CENTER NUMBER S INDEX NUMBER CHEMISTRY 8872/02 Paper 2 1 September 2015 2 hours Candidates answer section A on the Question Paper. Additional Materials: Answer Paper, Graph Paper Data Booklet READ THESE INSTRUCTIONS FIRST Write your Civics Group, centre number, index number and name on all the work you hand in. Write in dark blue or black pen. You may use an HB pencil for any diagrams or graphs. Do not use staples, paper clips, glue or correction fluid. Section A Answer all questions. Section B Answer two questions on separate answer paper. At the end of the examination, fasten all your work securely together. The number of marks is given in brackets [ ] at the end of each question or part question. This document consists of 16 printed pages. For Examiner’s Use A1 / 10 A2 / 10 A3 / 10 A4 / 10 Section B / 40 Paper 1 / 30 Total PRELIMINARY EXAMINATIONS HIGHER 1

2 2015 TJC H1 Chemistry Preliminary Exam [Turn over For examiner’s use 1 (a) An acidified solution of KC lO2 oxidises Fe2+(aq) to Fe 3+(aq). When 0.150 g of KC lO2 reacted with 0.500 mol dm -3 Fe2+(aq) in the presence of H +(aq), 11.30 cm 3 of Fe 2+(aq) was needed for complete reaction. (i) Suggest the final oxidation state of chlorine after complete reaction. Show your workings clearly.  No of moles of Fe2+ = 𝟏𝟏.𝟑𝟎 𝟏𝟎𝟎𝟎 𝐱 𝟎. 𝟓𝟎𝟎 = 𝟎. 𝟎𝟎𝟓𝟔𝟓 𝐦𝐨𝐥 No of moles of KClO2 = 𝟎.𝟏𝟓𝟎 𝟏𝟎𝟔.𝟔 =0.00141 mol  Mole ratio of KClO2 ;Fe2+ = 0.00141:0.00565 = 1: 4 KClO2≡ 4Fe2+  KClO2 gained 4e, since in KC lO2 is C l is +3 oxidation state and final state of Cl is -1 (ii) State the full electronic configuration of Fe3+.  1s22s22p63s23p63d5 [4] (b) The research student was given the second ionisation energies of seven consecutive elements in the Periodic Table as shown below: (i) Define, with the aid of an equation, what is meant by second ionisation energy of element B.  Second ionisation energy of element B is the minimum energy required to completely remove one mole of valence electrons from one mole of ground state ions in the gaseous state to form doubly charged gaseous ions.  B+(g) → B2+(g) + e Second ionisation energy /kJ mol-1 B C D E F G H       

3 2015 TJC H1 Chemistry Preliminary Exam [Turn over For examiner’s use (ii) With reference to the graph above, deduce the Group of the Periodic Table to which B is likely to belong. Explain your