Centre Number Candidate Number Candidate Name UNIVERSITY OF CAMBRIDGE LOCAL EXAMINATIONS SYNDICATE General Certificate of Education Ordinary Level CHEMISTRY 5070/3 PAPER 3 Practical MAY/JUNE SESSION 2000 Morning 1 hour 30 minutes Candidates answer on the question paper. Additional materials: As listed in Instructions to Supervisors Mathematical tables and/or calculator TIME 1 hour 30 minutes INSTRUCTIONS TO CANDIDATES Write your name, Centre number and candidate number in the spaces at the top of this page. Answer both questions. Write your answers in the spaces provided on the question paper. You should show the essential steps in any calculation and record all experimental results in the spaces provided on the question paper. If you are using semi-micro methods in Question 2, you should modify the instructions to suit the size of apparatus and the techniques you are using. INFORMATION FOR CANDIDATES The number of marks is given in brackets [ ] at the end of each question or part question. Question 1 carries 45% of the total marks and Question 2 carries 55%. Mathematical tables are available. You may use a calculator. Qualitative Analysis notes for this paper are printed on page 8. FOR EXAMINER S USE 1 2 TOTAL This question paper consists of 7 printed pages and 1 blank pages. SB (DJ) QF06370/3 UCLES 2000 [Turn over

1 Hydrated iron(ii) sulphate forms crystals of formula FeSO 4 O. 2 P is a solution of 27.0 g of FeSO 4 O dissolved in 1.00 dm 3 of dilute sulphuric acid. Q is 0.0200 mol/dm 3 potassium manganate(vii). You are to determine the value of x in the formula FeSO 4 O by titrating P with Q. No indicator is necessary since the products of the reaction are almost colourless and one drop of the potassium manganate(vii) solution in excess produces a pale pink colour. (a) Put the potassium manganate(vii) solution Q into the burette. Because the colour of Q is so intense, you may find it easier to read the top of the meniscus. Pipette a 25.0 cm 3 (or 20.0 cm 3 ) portion of P into a flask and titrate with Q. At first, the purple colour disappears rapidly. As the titration proceeds, this disappearance is less rapid. At the end-point, one drop of Q produces a pink colour that does not disappear on swirling. Record your results in the table, repeating the titration as many times as you consider necessary to achieve consistent results. Results Burette readings Titration number 1 2 Final reading/cm 3 Initial reading/cm 3 Volume of Q used/cm 3 Best titration results ( ) Summary Tick ( ) the best titration results. Using these results, the average volume of Q required was. cm 3. Volume of solution P used. cm 3 [12]

(b) 3 Q is 0.0200 mol/dm 3 potassium manganate(vii). Five moles of iron(ii) sulphate react with one mole of potassium manganate(vii). Using your results from (a), calculate the concentration, in mol/dm 3, of the iron(ii) sulphate in P. The concentration of iron(ii) sulphate in P is... mol/dm 3. [2] (c) P contains 27.0 g of FeSO 4 O dissolved in 1.00 dm 3 of solution. Using your answer from (b), calculate the relative molecular mass of FeSO 4 O. relative molecular mass of FeSO 4 O... [2] (d) The relative molecular masses of FeSO 4 and H 2 O are 152 and 18 respectively. Using your answer from (c), calculate the value of x in the formula FeSO 4 O. The value of x is.... [2] [Turn over

2 You are provided with three solutions R, S and T, all of which contain sodium salts. Carry out the following experiments and record your observations in the table. s on Solution R 4 no. 1 To a portion of solution R, add an equal volume of solution Q (from Question 1). Observations 2 (a) To a portion of acidified aqueous potassium manganate(vii), add a few drops of solution R. (b) Add an excess of solution R to the mixture from (a). Divide the mixture from (b) into two parts and use them for s 3 and 4 3 To a portion of the mixture from 2, add an equal volume of the organic liquid L. Mix well and leave to stand. 4 To a portion of the mixture from 2, add an equal volume of solution T and leave to stand.

5 To a portion of solution R, add an equal volume of aqueous silver nitrate. 5 [11] s on Solution S no. 6 To a portion of acidified aqueous potassium manganate (VII), add an equal volume of solution S. Observations 7 Divide this mixture into two parts and use them for s 7 and 8. To a portion of the mixture from 6, add an equal volume of the organic liquid L. Mix well and leave to stand. 8 To a portion of the mixture from 6, add an equal volume of solution T and leave to stand. 9 To a portion of solution S, add an equal volume of aqueous silver nitrate. [Turn over [5]

on Solution T 6 no. 10 To a portion of aqueous silver nitrate, add a few drops of solution T. Leave to stand for a few minutes, shaking occasionally. Observations Conclusions [3] The formula of the negative ion present in R is.... In 4, solution T is acting as.... S contains sodium and one other element. Suggest to which group in the Periodic Table this other element belongs....[3]

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8 NOTES FOR USE IN QUALITATIVE ANALYSIS for anions anion carbonate (CO 2 3 ) chloride (Cl ) [in solution] iodide (I ) [in solution] nitrate (NO 3 ) [in solution] sulphate (SO 2 4 ) [in solution] test add dilute acid acidify with dilute nitric acid, then add aqueous silver nitrate acidify with dilute nitric acid, then add aqueous lead(ii) nitrate add aqueous sodium hydroxide then aluminium foil; warm carefully acidify with dilute nitric acid, then add aqueous barium nitrate test result effervescence, carbon dioxide produced white ppt. yellow ppt. ammonia produced white ppt. for aqueous cations cation aluminium (Al 3 + ) ammonium (NH 4 + ) effect of aqueous sodium hydroxide white ppt., soluble in excess giving a colourless solution ammonia produced on warming effect of aqueous ammonia white ppt., insoluble in excess calcium (Ca 2 + ) copper(ii) (Cu 2 + ) iron(ii) (Fe 2 + ) iron(iii) (Fe 3 + ) zinc (Zn 2 + ) white ppt., insoluble in excess light blue ppt., insoluble in excess green ppt., insoluble in excess red-brown ppt., insoluble in excess white ppt., soluble in excess giving a colourless solution no ppt. or very slight white ppt. light blue ppt., soluble in excess giving a dark blue solution green ppt., insoluble in excess red-brown ppt., insoluble in excess white ppt., soluble in excess giving a colourless solution for gases gas test and test result ammonia (NH 3 ) carbon dioxide (CO 2 ) chlorine (Cl 2 ) hydrogen (H 2 ) oxygen (O 2 ) sulphur dioxide (SO 2 ) turns damp red litmus paper blue turns limewater milky bleaches damp litmus paper pops with a lighted splint relights a glowing splint turns aqueous potassium dichromate(vi) from orange to green