MJC_H2_CHEM_P3_Suggested_Ans.pdf

MJC_H2_CHEM_P3_Suggested_Ans.pdf - 2017 MJC H2 Chemistry...

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2017 MJC H2 Chemistry Prelim P3 Suggested Answers ©MJC Prelim 2017 H2 Chemistry MERIDIAN JUNIOR COLLEGE JC 2 Preliminary Examination H2 Chemistry Paper 3 ________________________________________________________________________ 1(a) (i) Comparing experiments 1 and 2, When [H 2 SO 4 ] is doubled and [C 6 H 6 ] is kept constant Rate of reaction increased 4 times Order of reaction with respect to H 2 SO 4 is 2 Comparing experiments 2 and 3, When [C 6 H 6 ] is increased 1.5 times and [H 2 SO 4 ] is kept constant Rate of reaction increased 1.5 times Order of reaction with respect to C 6 H 6 is 1 (ii) Rate = k [C 6 H 6 ] [H 2 SO 4 ] 2 (b) (i) Step 2: Step 3: Step 4: (ii) Step 2 (c) (i) Test: Br 2 (aq), r.t.p. Phenylamine: Decolourisation of orange bromine solution with the formation of a white precipitate. Diazonium salt: No decolourisation of orange bromine solution.
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2017 MJC H2 Chemistry Prelim P3 Suggested Answers ©MJC Prelim 2017 H2 Chemistry (ii) diazonium salt phenylamine derivative Electrophile is the diazonium salt (d) Reaction Deduction Q and R can rotate plane– polarized light. Q and R contains chiral carbon and has no plane of symmetry. 0.1 mol of compound Q produces 0.5 mol of carbon dioxide gas and 0.5 mol of water. Q contains 5 C atoms and 10 H atoms. 2 mol of Q undergoes acid– base reaction reaction with 1 mol of Na 2 CO 3 Q contains 1 carboxylic acid functional group. R undergoes oxidation when heated in an alkaline solution of iodine to give a yellow precipitate. Yellow precipitate is CH I 3 . R contains structure (and ) R undergoes nucleophilic substitution when heated with sodium hydroxide, followed by the addition of dilute and aqueous silver nitrate, a cream precipitate was formed. R contains a bromoalkane / halogenoalkane functional group. Cream precipitate is AgBr. Q and R undergo nucleophilic acyl substitution to form P. P contains an ester functional group
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