Unit CHEMESTRY PRACTICAL

Transcription

1 Unit CHEMESTRY PRACTICAL Important Points Chemical analysis : Analytical chemistry deals with qualitative and quantitative analysis of substances. Qualitative analysis : A salt consists of two parts known as radicals. The positively charged part of a salt (cation) which has been derived from a base is termed as basic radical and the negatively charged part of salt (anion) which has been derived from an acid is termed as acidic radical. In qualitative inorganic analysis, the given compound is analysed for the basic and acid radicals (i.e., the cations and the anions), that it contains. For + - example zinc blende is analysed for the Zn and S ions that it contains. Systematic Procedure for Qualitative Analysis of Inorganic Salts It involves the following steps : (1) Preliminary tests () Wet tests for acid radicals and () Wet tests for basic radicals. (1) Peliminary Test (i) Physical examination : It involves the study of colour, smell, density etc. Colour Black Oxides : Sulphides : Blue Hydrated, anhydrous 1 Salt Orange, some dichromate, ferricyanides (blackish brown) Green Nickel salts, hydrated ferrous salts, potassium permanganate KMnO ), some copper (II) salts Brownish yellow Dark brown Pale brown Light pink Reddish pink Red Yellow MnO, FeO, CuO, CoO, Ni O Ag S, CuS, CuS, FeS, CoS, Hydrated manganese salts Hydrated cobalt (II) salts NiS, PbS, HgS, Bi S CuSO CoSO KO ( K Cr O7 ), SbS SnS PbO, FeCl MnCO HgI Ag O, CdO, Fe O, CuCrO,, PbO CdS, PbI, AgBr, AgI, chromates (but yellow in aq. solution) (ii) Flame test : Characteristic flame colour : Certain metals and their salts impart specific colours to Bunsen burner flame. (a) Pb imparts pale greenish colour to the flame. (b) Cu and Cu salts impart blue or green colour to the flame. (c) Ba and its salts impart apple green colour to the flame. (d) Ca imparts brick red colour to the flame. (iii) Borax bead test : The transparent glassy bead ( NaBO + BO) when heated with inorganic salt and the colour produced gives some idea of cation present in it.

2 Colour of bead in oxidising flame Colour of bead in reducing flame Basic radical present Greenish when hot, blue in cold. Red and opaque Cu Yellow when hot Green Fe Brown in cold Grey or black or opaque Ni (iv) Charcoal cavity test (a) Compound fused in cavity directly Nature and colour of bead Yellow, soft bead which marks on paper White yellow when hot Grey metallic particles attracted by magnet Cation + Pb ZnO Fe, Ni, CO () Wet tests for acid radicals : Salt or mixture is treated with dil. H SO and also with conc. separately and by observing the types of gases evolved. Confirmatory tests of anions are performed. Observations with Dilute H SO Observations Acid Radical Confirmatory test Brisk effervescence with evolution of colourless and odourless gas. (carbonate) Gas turns lime water milky but milkyness disappears on passing gas inexcess, Brown fumes (Nitrite) Add KI and starch solution blue colour ; (colourless); (brown) Smell of rotten eggs smell) on heating (sulphide) starch??? blue colour Gas turn lead acetate paper black Sodium carbonate extract + sodium nitroprusside purple colour, Observation Acid Radical Confiramatory Test Colourless pungent gas - Cl giving white fumes with aq. NH OH (chloride) (i) Add MnO in the same test tube and heat -pale green Cl (ii) S.E.+ HNO + AgNO solution white ppt. soluble in aq. NH (iii) Chromyl chloride test Reddish brown fumes - Br (bromide) (iv) Add Mn O and heat yellowish brown Br gas (v) S.E.+ HNO + AgNO solution pale yellow ppt. partially soluble aq. NH (vi) Layer test Violet pungent vapours - I (iodide) (vii) S.E.+ HNO + AgNO yellow ppt. insoluble in aq. NH turning starch paper (viii) Layer test blue. Brown pungent fum es intensified by the addition of Cu - turnigs. Observations with concentrated H SO - NO (nitrate) (ix) Ring test gas

3 Reactions Chloride : (i) KCl conc. H SO KHSO + HCl + HCl + NH NH Cl (white fumes) (ii) D HCl + MnO MnCl + Cl + HO KCl + AgNO AgCl + KNO white ppt. AgCl + aq. NH ¾ Cl ¾ [ Ag( NH) ] soluble (iii) Chromyl- chloride test : Chloride + KCrO7 ( solid) + conc. HSO heat ¾¾ ¾ reddish brown vapours of chromyl -chloride ( CrO Cl). Pass these vapours into NaOH, when yellow Na CrO solution is formed. On adding CH COOH and ( CH COO) Pb, yellow ppt. of lead chromate ( PbCrO ) is formed. Bromide : (iv) (v) D KBr + conc. H SO KHSO + H ; HBr + MnO Br + H O + MnBr NaBr + AgNO AgBr + NaNO AgBr + aq. NH ¾ pale yellow ppt. ¾ [ Ag( NH ) ] partially soluble Br D (vi) Layer Test : S. E. + Cl water + CHCl instead of CHCl ); ¾¾ shake ¾¾ yellowish orange colour in layer or can be taken Iodide : (vii) Nitrate : NaBr + Cl NaCl + Br In case of (soluble orange yellow in CHCl) - I, violet colour of I in CHCl layer, NaI + Cl NaCl + I (violet) D KI + conc. H SO KHSO + HI ; HI + H SO I + H O + SO NaNO + + H SO NaHSO HNO HNO + O ¾ ¾ NO O H ; brown fumes Cu + HNO Cu( NO) + NO + H O (viii) Ring test : To water extract (all - NO are water soluble) add freshly prepared FeSO solution and then conc. H SO carefully by the side of the test - tube. A dark brown ring of at the interface between the two liquids is formed. NaNO + + HNO ; H SO NaHSO HNO + 6Fe SO + HSO Fe( SO ) + NO + HO [ Fe( H O) 6 ] SO + NO [ Fe( H O) 5 NO] SO + H O O) 5 NO] [ Fe ( H SO

4 Specific test in solution - (i) Sulphate : S.E. add dil. (to decompose CO until reaction ceases). Add BaCl solution. White ppt. insoluble in conc. HNO, BaCl + NaSO BaSO NaCl white ppt. + (ii) Borate : lgnite the mixture containing borate, conc. H SO burning splinter green edged flame of ethyl borate. Na + NaSO ; BO + HSO HBO (conc.) H BO + CH 5OH ( CH 5O) B + H ethanol D burns with green flame (volatile) O. And ethanol in a china -dish with a In presence of + Cu, perform this test in a test tube since salts are not volatile. (iii) S. E. HNO + ammonium molybdate solution. Heat, yellow crystalline ppt. confirms (iv) + NaPO + 1( NH) MoO + HNO D ( NH PO MoO NH NO NaNO H O ) yellow ppt. Arsenic also gives this test. Hence presence of phosphate should also be checked after group II. Fluoride : Sand +salt (F ) + conc. H SO ; heat and bring a water wetted rod in contact with vapours at the mouth of the test tube. A white deposit on the rod shows the presence to F. D NaF + H SO NaHSO + HF D SiO + HF SiF + H O SiF H SiF + H SiO H O () Wet tests for basic radicals : Group Basic radicals Group reagent I white Analysis of Basic Radicals Ppt. as Ag, Hg (I), Pb dil HCl Chloride ( AgCl, Hg Cl, PbCl ) II Cu, Cd, Pb, Hg (II), Bi, As, + + Sb, Sn III Al, Cr, Fe IV Zn, Ni, Mn, Co H S gas in presence of dil. HCl NH OH in presence of NH Cl H S ammonical medium in Sulphides CuS, As S ( etc.) Hydroxide, Al(OH) etc. Sulphides ( ZnS etc.) Explanation KSP values of chlorides are low, hence precipitated. Others have higher values hence not precipitated. KSP KSP values of sulphides are low hence - precipitated by low [ S ] (with common ionization of H H S + ion. HCl ion) decreases which gives low - [ S ]. Hence II group is precipitated. Others with higher K SP values not precipitated. KSP values of Al(OH) etc. are low. + NH Cl (with common NH ion) decreases ionization of NH OH - giving low [ OH ]. Hence group III is precipitated. KSP values of sulphides of group IV are high hence precipitation takes place - in higher [ S ]. Basic medium increases ionization of H S increasing [ S - ] hence precipitation of group IV.

5 Group Basic radicals Group reagent V Ca, Ba, Sr VI Mg,( Na, K also NHOH included) + Na HPO Ppt. as ( NH ) CO + Carbonates ( CaCO NH Cl etc.) White ppt. ( MgHPO ) Explanation KSP values of carbonate are les s than + that of group VI ( Mg ) hence precipitation before + Mg. 0 (Zero) + NH Tested independently from original solution. Chemical reactions involved in the tests of basic radicals Group I : When dil. HCl is added to original solution, insoluble chlorides of lead, silver mercurous mercury are precipitated. Pb ( NH + HNO ) + HCl PbCl ; AgNO + HCl AgCl + HNO Hg ( NO + HNO Pb + (lead) ) + HCl HgCl (i) PbCl is soluble in hot water and on cooling white crystals are again formed. (ii) The solution of PbCl gives a yellow precipitate with potassium chromate solution which is insoluble in acetic acid but soluble in sodium hydroxide. PbCl + K CrO PbCrO + KCl ; yellow ppt. PbCrO + NaOH NaPbO + NaCrO + H O (iii) The solution of PbCl forms a yellow precipitate with potassium iodide solution. PbCl + KI PbI KCl Yellow + ppt. (iv) White precipitate of lead sulphate is formed with dilute H SO. The precipitate is soluble in ammonium acetate, PbCl + H SO PbSO HCl ; + PbSO + SO + CH COONH Pb( CH COO) ( NH ) Group II : When hydrogen sulphide is passed in acidified solution, the radicals of second group are precipitated as sulphides. The precipitate is treated with yellow ammonium sulphide. The sulphides of IIB are first oxidised to higher sulphides which then dissolve to form thio -compounds. Ag S + As S S + ( NH ) S ( NH ) 5 Sb S + Sb S S + ( NH ) S ( NH ) SnS + ( NH S + SnS ) S ( NH ) 5 5

6 As ¾ S5 + ( NH) S ¾ ( NH) AsS Ammonium thioarsenate Sb ¾ S5 + ( NH ) S ¾ ( NH ) SbS Ammonium thioantimonate SnS ¾ + ( NH ) S ¾ ( NH ) SnS Ammonium thiostannate All the three are soluble. In case, the precipitate does not dissolve in yellow ammonium sulphide, it may be either HgS or PbS or Bi S or CuS or CdS. The precipitate is heated with dilute HNO. Except, all other sulphides of are soluble. PbS + 8HNO Pb( NO) + NO + S + HO BiS + 8 HNO Bi( NO) + NO + S + HO CuS + 8HNO Cu( NO) + NO + S + HO CdS + 8HNO Cd( NO) + NO + S + HO Pb + (lead) In case the sulphide dissolves in dilute HNO, a small part of the solution is taken. Dilute H SO is added. If lead is present, a white precipitate of lead sulphate appears, Pb ( NO) + HSO PbSO + HNO (White ppt.) In absence of lead, the remaining solution is made alkaline by the addition of excess of NH OH. Bismuth forms a white precipitat of Bi ( OH), copper forms a deep blue coloured solution while cadmium forms a colourless soluble complex, Bi NO) + NHOH Bi( OH) + NH NO White ppt. ( Cu ( NO ) + NHOH [ Cu( NH) ]( NO) + H Tetrammine cupric nitrate (deep blue solution) O ; Cd ( NO ) + NH OH [ Cd( NH ) ]( NO) + H Tetrammine cadmium nitrate Cu + (copper) : O (colourless solution) Blue coloured solution is acidified with acetic acid. When potassium ferrocyanide is added a chocolate coloured precipitate is formed, Cu NH ) ( NO) + CH COOH Cu ( NO) + CH COONH ( Cu ( NO) + K[ Fe( CN) 6] Cu[ Fe( CN) 6 + KNO Chocolate ppt. 6

7 Group III : Hydroxides are precipitated on addition of excess of ammonium hydroxide in presence of ammonium chloride. AlCl + NHOH Al( OH) + NHCl Gelatinous ppt. CrCl + NHOH Cr( OH) + NHCl Green ppt. FeCl + NHOH Fe( OH) + NHCl Brownish red ppt. Fe + (iron) : The brownish red precipitate dissolves in dilute HCl. The solution is divided into two parts. Part I : K solution is added which forms deep blue solution or precipitate. [ Fe( CN) 6] Fe( OH) + HCl FeCl + HO FeCl + K [ Fe( CN) ] Fe [ Fe( CN) ] 1KCl Prussian blue Part II : Addition of potassium thiocyanate solution gives a blood red colouration. FeCl + KCNS Fe( CNS) KCl + Blood red colour Al + (aluminium) : The gelatinous precipitate dissolves in NaOH, Al( OH) + NaOH NaAlO + HO Soluble The solution is boiled with ammonium chloride when Al (OH) is again formed. NaAlO ( + NaCl + NH + NH Cl + H O Al OH) Group IV : On passing H S through the filtrate of the third group, sulphides of fourth group are precipitated. NiS and CoS are black and insoluble in concentrated HCl while MnS (buff coloured), ZnS (colourless) are soluble in conc. HCl. Zn + (zinc) : The sulphide dissolves in HCl. ZnS + HCl ZnCl + HS When the solution is treated with NaOH, first a white precipitate appears which dissolves in excess of NaOH ZnCl + NaOH Zn( OH) + NaCl Zn( OH) + NaOH NaZnO + HO White ppt. (Soluble) On passing H S, white precipitate of zinc sulphide is formed Na ZnO + HS ZnS + NaOH White ppt. Mn + (manganese) : Manganese sulphide dissolves in HCl MnS + HCl MnCl + HS On heating the solution with NaOH and Br -water, manganese dissolve gets precipitated. MnCl + NaOH Mn( OH) + NaCl Mn( OH) + O MnOHO The precipitate is treated with excess of nitric acid and PbO or Pb O (red lead). The contents are heated. The formation of permanganic acid imparts pink colour to the supernatant liquid. MnO ¾ NO + H O + O + HNO ¾ Mn( ) Mn ( NO) + 5PbO + 6HNO The above test fails in presence of HCl. HMnO + 15 Pb (NO ) + 1 H O Permanganic acid (pink) 7

8 Ni + (nickel) and Co + (cobalt) The black precipitate is dissolved in aqua - regia. NiS + 6HCl + HNO NiCl + NO + S + HO CoS + 6HCl + HNO CoCl + NO + S + HO The solution is evaporated to dryness and residue extracted with dilute HCl. It is divided into three parts. Part I : Add NH OH (excess) and dimethyl glyoxime. A rosy red precipitate appears, if nickel is present, CH - C = NOH NiCl + + NH OH CH - C = NOH CH CH - C = N OH O Ni + NH Cl + H O - C = N O OH N = C - CH N = C - CH Part II : Add of cobalt. CH COOH in excess and. KNO The appearance of yellow precipite confirms the presence KNO + + CHCOOH CHCOOK HNO CoCl + KNO Co( NO ) KCl + Co( NO ) + HNO Co( NO) + NO + HO Co( NO) + KNO K[ Co( NO) 6] Part III : Solution containing either nickel or cobalt is treated with NaHCO and bromine water. Appearance of apple green colour is observed, the solution is heated when black precipited is formed, which shows the presence of nickel, CoCl + NaHCO Co( HCO ) NaCl + Co ( HCO + CO ) + NaHCO NaCo( CO) + HO Br + H O HBr + O Na Co( CO) + HO + O NaCo( CO) + NaOH sod. cobalti carbonate (Green colouration) NiCl NaCl + H O + CO + NaHCO NiCO + NiCO + [ O] Ni O + CO (Black) 8

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10 M.C.Q. 1. In borax bead test, which of the following compound is formed [CBSE PMT 00] (a) Meta borate (b) Tetra borate (c) Double oxide (d) Ortho borate. The metal that does not give the borax -bead test is [MP PMT 1999] (a) Chromium (b) Nickel (c) Lead (d) Manganese. Which of the following is coloured compound? [BCECE 005] (a) CuF (b) CuI (c) NaCl (d) MgCl. The alkaline earth metal that imparts apple green colour to the bunsen flame when introduced in it in the form of its chloride is [EAMCET 1979] (a) Barium (b) Strontium (c) Calcium (d) Magnesium 5. Which gives violet coloured bead in borax bead test [BHU 1988; MP PET 1997] (a) Fe + (b) Ni + (c) Co + (d) Mn + 6. When concentrated H SO is added to dry KNO, brown fumes evolve. These fumes are [CPMT 1988; IIT 1987] (a) SO (b) SO (c) NO (d) NO 7. Which one of the following salt give green coloured flame when the salt is tested by Pt wire (a) Barium salt (b) Calcium salt (c) Borate (d) Lead salt 8. Sodium sulphite on heating with dilute HCl liberates a gas which [NCERT 197] (a) Turns lead acetate paper black (b) Turns acidified potassium dichromate paper green (c) Burns with a blue flame (d) Smells like vinegar 9. Starch -iodide paper is used for the test of (a) Iodine (b) Iodide ion (c) Oxidising agent (d) Reducing agent 10. Which of the following salt gives white precipitate with solution and dil. solution and gives green flame test (a) CuCl (b) BaCl (c) pbcl (d) Cu(NO ) 11. Two gases when mixed give white dense fumes, the gases are (a) NH and SO (b) SO and steam (c) NH and HCl (d) NH and N O 1. Blue borax bead is obtained with [MADT Bihar 198; MP PET 1995] (a) Zn (b) Cobalt (c) Chromium (d) Fe 1. Which of the following imparts green colour to the burner flame [DCE 00] (a) B(OMe) (b) Na(OMe) (c) Al(OPr) (d) Sn(OH) 50

11 1. A colourless gas with the smell of rotten fish is [AFMC 005] (a) H S (b) PH (c) SO (d) None of these 15. MnO and H SO added to NaCl, the greenish yellow gas liberated is [Orissa JEE 005] (a) Cl (b) NH (c) N (d) H 16. Which of the following statement(s) is(are) correct when a mixture of NaCl and K Cr O 7 is gently warmed with conc H SO. [IIT 1998; CPMT 1988; AMU 198; MP PMT 00] (a) A deep red vapour is evolved (b) The vapour when passed into NaOH solution gives a yellow solution of Na Cr O 7 (c) Chlorine gas is evolved (d) Chromyl chloride is formed 17. Which of the following combines with Fe (II) ions to form a brown complex [AIIMS 198, 87; AFMC 1988; CBSE PMT 000; Pb. PMT 000; MP PET 000, 01] (a) N O (b) NO (c) N O (d) N O Which of the following will not produce a precipitate with AgNO solution [MP PMT 1990] (a) F (b) Br (c) CO (d) PO 19. Which of the following gives black precipitate when H S gas is passed through its solution [CPMT 197] (a) Acidic AgNO (b) Mg(NO) (c) Ammonical BaCl (d) Copper nitrate 0. A salt gives violet vapours when treated with conc. HSO. It contains [DPMT 1981; CPMT 1971] (a) Cl (b) I (c) Br (d) NO 1. When water is added to a salt solution containing chloroform, chloroform layer turns violet. Salt contains [CPMT 198] (a) Cl (b) I (c) NO (d) S. Phosphate radical with ammonium molybdate gives precipitate of which colour (a) Violet (b) Pink (c) Canary yellow (d) Green. Which compound is soluble in NH OH [AFMC 1987] (a) PbCl (b) PbSO (c) AgCl (d) CaCO. Nitrates of all the metals are [DPMT 198, 89] (a) Coloured (b) Unstable (c) Soluble in water (d) Insoluble in water 5. Nitrate is confirmed by ring test. The brown colour of the ring is due to the formation of [EAMCET 1979; AFMC 1981, 88, 90; RPET 1999; MP PMT 000; MP PET 00; CPMT 00] (a) Ferrous nitrite (b) FeSO NO (c) FeSO NO (d) Ferrous nitrate 6. Aqueous solution of a salt when treated with AgNO solution gives a white precipitate, which dissolves in NH OH. Radical present in the salt is (a) Cl (b) Br (c) I (d) NO 7. When CO is passed into lime water it turns milky. When excess of CO is passed, milkyness disappears because (a) Reaction is reversed (b) Water soluble Ca(HCO ) is formed (c) Vaporisable calcium derivative is formed (d) None of these 51

12 8. A mixture when heated with conc. H SO with MnO brown fumes are formed due to (a) Br (b) NO (c) Cl (d) I 9. In the test of sulphate radical, the white precipitate of sulphate is soluble in (a) Conc. HCl (b) Conc. H SO (c) Conc. HNO (d) None of these 0. Which reagent is used to remove SO and Cl [Pb. PMT 00] (a) BaSO (b) NaOH (c) Pb(NO ) (d) KOH is formed when potassium iodide is heated with conc. H SO [CPMT 1971] (a) HI (b) I (c) HIO (d) KIO. Chromyl chloride test is performed for the confirmation of the presence of the following in a mixture [CPMT 1990; KCET 199; RPET 1999] (a) Sulphate (b) Chromium (c) Chloride (d) Chromium and chloride. A solution of a salt in dilute sulphuric acid imparts deep blue colour with starch iodine solution it confirms the presence of which of the following [MP PET 00; NCERT 197; CPMT 1977] (a) NO (b) I (c) NO (d) CH COO. Ammonia reacts with excess of chlorine to form [DPMT 000] (a) N and HCl (b) NH Cl and NCl (c) NCl and HCl (d) N and NH Cl 5. Which of the following anions would decolourise acidified KMnO solution (a) SO (b) S (c) NO (d) CH COO 6. The gas which is absorbed by ferrous sulphate solution giving blackish brown colour is [AMU 1999] (a) NO (b) CO (c) N (d) NH 7. Which one of the following anions is not easily removed from aqueous solutions by precipitation [IIT 1995] (a) Cl (b) NO (c) CO (d) SO 8. Na CO cannot be used to identify [BVP 00] (a) CO (b) SO (c) S (d) SO 9. The number of hydroxide ions, produced by one molecule of sodium carbonate (Na CO ) on hydrolysis is [Pb. CET 00] (a) (b) 1 (c) (d) 0. By passing KMnO gas in acidified H S solution, we get [MP PET 1997] (a) K S (b) S (c) K SO (d) MnO 1. Which of the following doesn t give a ppt. with silver nitrate solution. [J & K 005] (a) Ethyl bromide (b) Sodium bromide (c)calcium chloride (d) Sodium chloride. Which sulphide is soluble in (NH ) CO (a) SnS (b) AS S (c) Sb S (d) CdS. When acetic acid and K [Fe(CN) 6 ] is added to a copper salt, a chocolate precipitate is obtained of the compound (a) Copper cyanide (c) Basic copper sulphate 5 (b) Copper ferrocyanide (d) Basic copper cyanide

13 . A precipitate of the following would be obtained when HCl is added to a solution of stannous sulphide (SnS) in yellow ammonium sulphide [CPMT 1977; NCERT 197] (a) SnS (b) SnS (c) Sn S (d) (NH ) SnS 5. The compound insoluble in acetic acid is [CPMT 1989] (a) Calcium oxide (b) Calcium carbonate (c) Calcium oxalate (d) Calcium hydroxide 6. Which of the following give white precipitate when HCl is added to its aqueous solution (a) Hg + (b) Mg ++ (c) Zn ++ (d) Cd Reagent used in the qualitative analysis of IVth group is (a) HCl (b) H S (alkaline) (c) (NH ) S (d) None of these 8. Which of the following pairs would be expected to form precipitate when solution are mixed [NCERT 198] (a) K +, SO (b) Na +, S (c) Ag +, NO (d) Al +, OH 9. Addition of solution of oxalate to an aqueous solution of mixture of Ba +, Sr + ylku Ca + and will precipitate [MP PMT 1985] (a) Ca + (b) Ca +, Sr + (c) Ba +, Sr + (d) All the three 50. Distinguishing reagent between silver and lead salts is [MADT Bihar 198] (a) H S gas (b) Hot dilute HCl solution (c) NH Cl (S) + NH OH (aq) (solid) + solution (d) NH Cl (S) (solid) + (NH ) CO (aq) solution 51. The ion that cannot be precipitated by both HCl and H S is [IIT 198; CPMT 1989] (a) Pb + (b) Cu + (c) Ag + (d) Sn + 5. Pb(CH COO) gives.colour with H S [DPMT 000] (a) Orange (b) Red (c) Black (d) White 5. Fe + ion can be distinguished by Fe + ion by [DPMT 000] (a) NH SCN (b) AgNO (c) BaCl (d) None of these 5. Which of the following change the colour of the aqueous solution of FeCl [Roorkee Qualifying 1998] (a) K [Fe(CN) 6 ] (b) H S (c) NH CNS (d) KCNS 55. Which of the following mixture is chromic acid [Pb. PMT 000] (a) K Cr O 7 and HCl (b) K SO conc. H SO (c) K Cr O 7 and conc. H SO (d) H SO and HCl 56. If Na + ion and S ion is larger than Cl ion, which of the following will be least soluble in water [AMU (Engg.) 1999] (a) MgS (b) NaCl (c) Na S (d) MgCl 57. Lead sulphate is soluble [MP PET 1999] (a) In conc. nitric acid (b) In conc. hydrochloric acid (c) In a solution of ammonium acetate (d) In water 58. When H S gas is passed through the HCl containing aqueous solutions of CuCl, HgCl, BiCl and CoCl, which does not precipitate out [MP PMT 00] (a) CuS (b) HgS (c) Bi S - (d) CoS 5

14 59. Group reagent for analytic group IV is [Kurukshetra CET 00] (a) NH Cl + NH OH (b) NH Cl + NH OH + H S (c) NH OH + (NH ) CO (d) HCl + H S 60. When H S is passed through Hg S we get [AIEEE 00] (a) HgS (b) HgS + Hg S (c) Hg S + Hg (d) Hg S 61. [X] + H SO [Y] a colourless gas with irritating smell [Y] + K Cr O 7 + H SO green solution [X] and [Y] is [IIT -JEE (Screening) 00] (a) SO, SO (b) Cl, HCl (c) S, H S (d) CO, CO 6. Concentrated sodium hydroxide can separate a mixture of [MP PMT 000] (a) Zn + and Pb + (b) Al + and Zn + (c) Cr + and Fe + (d) Al + and Cr + 6. What product is formed by mixing the solution of K [Fe(CN) 6 ] with the solution of FeCl [Roorkee 1989] (a) Ferro -ferricyanide (b) Ferric -ferrocyanide (c) Ferri -ferricyanide (d) None of these 6. When H S is passed through a mixture containing Cu +, Ni +, Zn + in acidic solution then ion will precipitate [RPMT 00] (a) Cu +, Ni + (b) Ni + (c) Cu +, Zn + (d) Cu Ferric ion forms a prussian blue coloured ppt. due to [CPMT 1980; BHU 1980; MP PET 1995; Kurukshetra CEE 1998; RPET 1999; MP PMT 001] (a) K [Fe(CN) 6 ] (b) Fe [Fe(CN) 6 ] (c) KMnO (d) Fe(OH) 66. A 0. M HCl solution contains the following ions Hg +, Cd +, Sr +, Fe + ylku Cu +. The addition of H S to above solution will precipitate [CPMT 197] (a) Cd, Cu and Hg (b) Cd, Fe and Sr (c) Hg, Cu and Fe (d) Cu, Sr and Fe 67. Which of the following gives a ppt. with Pb(NO ) but not with Ba(NO ) [CPMT 1979; MP PET 1997] (a) NaCl (b) Sodium acetate (c) Sodium nitrate (d) Sodium hydrogen phosphate 68. In the group III radicals, in place of NH Cl which of the following can be used [AIIMS 1980, 8; MP PMT 1985] (a) NH NO (b) (NH ) SO (c) (NH ) (d) NaCl 69. Which compound does not dissolve in hot dilute HNO [IIT 1996] (a) HgS (b) PbS (c) CuS (d) CdS 70. Which of the following sulphate is insoluble in water [MNR 1995] (a) CuSO (b) CdSO (c) PbSO (d) BaSO 71. Mark the compound which turns black with NH OH [AFMC 1981; MP PMT 1995] (a) Lead chloride (b) Mercurous chloride (c) Mercuric chloride (d) Silver chloride 7. Colour of cobalt chloride solution is [AFMC 1981] (a) Pink (b) Black (c) Colourless (d) Green 7. Nessler s reagent is used to detect [CPMT 1989; AIIMS 1997; MP PET 1999] (a) CrO (b) PO (c) MnO (d) NH + 5

15 7. Fe(OH) can be separated from Al(OH) by addition of [BHU 1981] (a) Dil. HCl (b) NaCl solution (c) NaOH solution (d) NH Cl and NH OH 75. The reagents NH Cl and aqueous NH will precipitate [IIT 1991] (a) Ca + (b) Al + (c) Mg + (d) Zn Addition of SnCl to HgCl gives ppt [BVP 00] (a) White turning to red (b) White turning to gray (c) Black turning to white (d) None of these 77. Heamoglobin is a complex of [CPMT 00] (a) Fe + (b) Fe + (c) Fe + (d) Cu In Nessler s reagent for the detection of ammonia the active species is [Kerala (Med.) 00] (a) Hg Cl (b) Hg + (c) Hg I (d) HgI 79. Which one of the following sulphides is only completely precipitated when the acidic solution is made dilute [MP PET 000] (a) HgS (b) PbS (c) CdS (d) CuS 80. A reagent used to test the presence of ion is [KCET 1998] (a) H S (b) NH CNS (c) K [Fe(CN) 6 ] (d) K [Fe(CN) 6 ] 81. The following four solutions are kept in separate beakers and copper metal is put in each of them. Which solution will become blue after some time [MP PMT 00] (a) AgNO solution (b) Zn(NO ) solution (c) Ba(NO ) solution (d) NaNO solution 8. In qualitative analysis, in order to detect second group basic radical, H S gas is passed in the presence of dilute HCl to [KCET 00] (a) Increase in dissociation of H S (b) Decrease the dissociation of salt solution (c) Decrease the dissociation of H S (d) Increase the dissociation of salt solution 8. Sodium nitroprusside when added to an alkaline solution of sulphide ions produce a [AFMC 005] (a) Red colouration (b) Blue colouration (c) Purple colouration (d) Brown colouration 8. If 0 ml of 0.5 N strong acid and 0 ml of 0. N of strong base are mixed, then the resulting solution is [KCET 00] (a) 0.5 N basic (b) 0. N acidic (c) 0.5 N acidic (d) 0. N basic ml of 10 M H SO is mixed to 100 ml 1M NaOH solution. The resultant solution will be [NCERT 1971] (a) Acidic (b) Neutral (c) Weakly alkaline (d) Strongly alkaline 86. The equivalent weight of KMnO in alkaline medium will be [MP PMT 001] (a) 1.60 (b) 5.66 (c) (d) Phenolphthalein is most suitable indicator for the titration of [MP PMT 000] (a) CH COOH and NH OH (b) CH COOH and NaOH (c) HCl and NH OH (d) H CO and NH OH ml of a N solution of KMnO just reacts with 0 ml of a solution of oxalic acid. The weight of oxalic acid crystals in 1N of the solution is [JIPMER 1999] (a) 1.5 g (b) 16 g (c) 6 g (d) 6. g 55

16 ANSWERS KEY 1 a 16 a,b,d 1 b 6 a 61 c 76 b c 17 b c 7 b 6 c 77 b a 18 d a 8 d 6 b 78 d d 19 a c 9 d 6 d 79 c 5 d 0 b 5 b 50 b 65 b 80 d 6 d 1 b 6 a 51 b 66 a 81 a 7 a c 7 b 5 c 67 a 8 c 8 b c 8 a 5 a 68 a 8 c 9 a c 9 a 5 a 69 a 8 d 10 b 5 b 0 b 55 c 70 d 85 a 11 c 6 a 1 a 56 a 71 b 86 d 1 b 7 b b 57 a 7 a 87 d 1 a 8 a b 58 d 7 d 88 c 1 b 9 d b 59 b 7 c 15 a 0 c 5 c 60 c 75 b 56