RVHS Prelim P3_QP

1 River Valley High School 9729/03 [Turn over 2018 Preliminary Examinations RIVER VALLEY HIGH SCHOOL YEAR 6 PRELIMINARY EXAMINATION CANDIDATE NAME CLASS 6 CENTRE NUMBER S INDEX NUMBER H2 CHEMISTRY 9729/03 Paper 3 Free Response 18 September 2018 2 hours Candidates answer on separate paper. Additional Materials: Answer Paper Cover Page Data Booklet READ THESE INSTRUCTIONS FIRST Write your name, class, centre number and index number on all the work you hand in. Write in dark blue or black pen on both sides of paper. You may use a soft pencil for any diagrams, graphs or rough working. Do not use staples, paper clips, highlighters, glue or correction fluid. Section A Answer all questions. Section B Answer one question. Begin each question on a fresh sheet of paper. The use of an approved scientific calculator is expected, where appropriate. A Data Booklet is provided. Do not write anything on it. You are reminded of the need for good English and clear presentation in your answers. The number of marks is given in brackets [ ] at the end of each question or part question. At the end of the exami nation, fasten all your work secu rely together, wit h the cover page on top. This document consists of 15 printed pages and 1 blank page.

2 River Valley High School 9729/03 [Turn over 2018 Preliminary Examinations Section A Answer all the questions in this section. 1 (a) (i) Phosphorus reacts with • F 2 to produce PF5 as the only product. • C l2 to give both PCl5 and PCl3. • Br 2 and I2 to give PBr3 and PI3 respectively. With reference to the Data Booklet, explain the difference in oxidation states of phosphorus in the phosphorus-containing compounds formed. [3] (ii) The table below gives the pKa values of the hydrogen halides. hydrogen halide p Ka HF 3.17 HCl –7 HBr –9 HI –10 Explain the trend in the pKa values. [2] (b) The following reaction scheme shows the formation of an alcohol via the Grignard reaction. RM g B r R' R" O O R' R" R MgBr dilute acid OH R' R" R + MgBr(OH) Step I Step II (i) Suggest the type of reaction undergone in Step II. [1] (ii) Suggest the identities of a suitable carbonyl compound and Grignard reagent to form 1-methylcyclohexan-1-ol. [2] (iii) The reaction between the car bonyl compound and the Grignard reagent suggested in (b)(ii) is a nucleophilic addition. Propose the mechanism for this reaction, assuming that the Grignard reagent (R-MgBr) produces the , as the reacting species to form 1-methylcyclohexan-1-ol. [3] Grignard reagent

3 River Valley High School 9729/03 [Turn over 2018 Preliminary Examinations (c) Calcium phosphate, Ca3(PO4)2, is a sparingly soluble salt. .. (i) Write the expression for the solubility product of calcium phosphate. [1] (ii) Given that the solubility of calcium phosphate in water is 1.14 × 10 –7 mol dm –3, calculate the solubility product of calcium