CIE Jun 2013 v2 Paper 3 Q2

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Examiners For Use Qualitative Analysis At each stage of any test you are to record details of the following.colour changes seen the formation of any precipitate the solubility of such precipitates in an excess of the reagent added Where gases are released they should be identi ed by a test, described in the appropriate place in your observations. You should indicate clearly at what stage in a test a change occurs. Marks are not given for chemical equations. No additional tests for ions present should be attempted. If any solution is warmed, a boiling tube MUST be used. Rinse and reuse test-tubes and boiling tubes where possible. Where reagents are selected for use in a test, the name or correct formula of the element or compound must be given. (a) FB 4, FB 5 and FB 6 are aqueous solutions of salts. Each contains a different anion which is either sulfate, chloride or nitrate. Using the Qualitative Analysis Notes on page 11, select reagents to allow you to identify positively which anion is in each salt using the minimum number of tests. Record your reagents and your observations in the table below. Indicate where a test is unnecessary using a dash, . reagent(s) FB 4 FB 5 FB 6 II III IV [5] [Turn overUCLES 2013 9701/32/M/J/13<br /> Examiners For Use (b) Many cations are identi ed by using aqueous sodium hydroxide and aqueous ammonia in small amounts and then to excess. Carry out the following tests and record all your observations in the table provided below. FB 4 observations FB 5 FB 6 test (i) To 1 cm depth of salt solution in a test-tube, add a few drops of aqueous sodium hydroxide, then add excess. (ii) To 1 cm depth of salt solution in a test-tube, add a few drops of aqueous ammonia, then add excess. (c) From your observations in (a) and (b), identify as many of the ions present as possible. FB 4 FB 5 FB 6 [3] cation anion [3]UCLES 2013 9701/32/M/J/13<br /> (d) One or more of the solutions contain(s) a second cation, the hydrogen ion, H+. (i) State two tests that can be used to show whether H+ is present. test 1test 2(ii) Carry out your tests and record your observations in a suitable form in the space below. Examiners For Use II III IV (iii) Identify which of the solutions FB 4, FB 5 and FB 6 contain(s) the hydrogen ion, H+. H+ is present in. [5] [Total: 16]UCLES 2013 9701/32/M/J/13 [Turn over<br /> 10 Qualitative Analysis Notes Key: [ppt. = precipitate] 1 Reactions of aqueous cations ion aluminium, Al 3+(aq) ammonium, NH4 +(aq) barium, Ba2+(aq) calcium, Ca2+(aq) reaction with NaOH(aq) NH3(aq) white ppt. soluble in excess white ppt. insoluble in excess no ppt. ammonia produced on heating no ppt. (if reagents are pure) no ppt. white ppt. with high [Ca2+(aq)] no ppt. chromium(III), Cr3+(aq) grey-green ppt. soluble in excess giving dark green solution grey-green ppt. insoluble in excess copper(II), Cu2+(aq) pale blue ppt. insoluble in excess blue ppt. soluble in excess giving dark blue solution green ppt. turning brown on contact with air insoluble in excess green ppt. turning brown on contact with air insoluble in excess iron(II), Fe2+(aq) iron(III), Fe3+(aq) lead(II), Pb2+(aq) red-brown ppt. insoluble in excess white ppt. soluble in excess magnesium, Mg2+(aq) white ppt. insoluble in excess red-brown ppt. insoluble in excess white ppt. insoluble in excess white ppt. insoluble in excess manganese(II), Mn2+(aq) off-white ppt. rapidly turning brown on contact with air insoluble in excess off-white ppt. rapidly turning brown on contact with air insoluble in excess zinc, Zn2+(aq) white ppt. soluble in excess white ppt. soluble in excess [Lead(II) ions can be distinguished from aluminium ions by the insolubility of lead(II) chloride.]UCLES 2013 9701/32/M/J/13<br /> 2 Reactions of anions 11 ion carbonate, CO3 2 chromate(VI), CrO4 2(aq) chloride, Cl (aq) bromide, (aq) Br iodide, (aq) I nitrate, NO3 (aq) nitrite, NO2 (aq) sulfate, SO4 2(aq) sul te, SO3 2(aq) CO2 liberated by dilute acids reaction yellow solution turns orange with H+(aq); gives yellow ppt. with Ba2+(aq); gives bright yellow ppt. with Pb2+(aq) gives white ppt. with Ag+(aq) (soluble in NH3(aq)); gives white ppt. with Pb2+(aq) gives cream ppt. with Ag+(aq) (partially soluble in NH3(aq)); gives white ppt. with Pb2+(aq) gives yellow ppt. with Ag+(aq) (insoluble in NH3(aq)); gives yellow ppt. with Pb2+(aq) NH3 liberated on heating with OH(aq) and Al foil NH3 liberated on heating with OH(aq) and Al foil; NO liberated by dilute acids (colourless NO(pale) brown NO2 in air) gives white ppt. with Ba2+(aq) or with Pb2+(aq) (insoluble in excess dilute strong acids) SO2 liberated with dilute acids; gives white ppt. with Ba2+(aq) (soluble in excess dilute strong acids) 3 Tests for gases gas ammonia, NH3 carbon dioxide, CO2 chlorine, Cl 2 hydrogen, H2 oxygen, O2 sulfur dioxide, SO2 test and test result turns damp red litmus paper blue gives a white ppt. with limewater (ppt. dissolves with excess CO2) bleaches damp litmus paper pops with a lighted splint relights a glowing splint turns acidi ed aqueous potassium dichromate(VI) from orange to greenUCLES 2013 9701/32/M/J/13<br />

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