Salt Analysis and Qualitative Analysis

SALT ANALYSIS AND QUALITATIVE ANALYSIS HINTS & SOLUTIONS 17. (A) 3AgCl  + AsO33–  Ag3AsO3  (yellow) + 3Cl– AgI is unaffected by this treatment. EXERCISE - 1 Single Choice 1. SO32– + Zn + 8H+  H2S  + 3Zn2+ + 3H2O Pb2+ + S2–  PbS  (black) Ag+ + S2–  Ag2S  (black) 2MnO4– + 5H2S + 6H+  2Mn2+ + 5S + 8H2O 3. 5. 8. SO32– + Ba(OH)2  BaSO3  (white) + 2OH–. (B) AgCl + 2NH3  [Ag(NH3)2]Cl AgI is not soluble in dilute ammonia solution. (C) Both soluble in potassium cyanide, forming soluble complexes. (D) Both insoluble in dilute HNO3. 19. OCl– + 3I– + H2O  I3– + 2OH– + Cl–. I3– + starch  blue -black spot on starch paper due to the formation of iodine-starch adsorption complex. 3SO2 + Cr2O72– + 2H+  2Cr3+ (green colour solution) + 3SO42– + H2O. 20. 2I– + Cl2  I2 (violet) + 2Cl– (i) Cr2O72– + 3SO2 + 2H+  2Cr3+ (green) + 3SO42– + H2O ; CO2 and O2 do not give reactions with acidified K2Cr2O7 22. Ba2+ + CrO42–  BaCrO4  (yellow) ; (ii) Ca(OH)2 + CO2  CaCO3  (white) + H2O ; O2 does not give reaction with acidified K2Cr2O7. (iii) O2 dissolves in pyrogallol. 23. NH4+ + [PtCl6]2–  (NH4)2[PtCl6]  (yellow). (A) Cd2+ (aq) + H2S (g)  CdS  (yellow) + 2H+ (aq) (B) Co 3 2– + 4Hg 2+ + 3H 2 O  Hg 4 O 3 CO 3  (reddish-brown) + 6H+ HCO3– (aq) does not give precipitate. (C) SO3 + 3Zn + 8H  H2S  + 3Zn + 3H2O 2– + 2+ (D) 5SO2 + 2IO3– + 4H2O  I2 + 5SO42– + 8H+ 10. Br– + H2SO4  HBr + HSO4– ; HBr + H2SO4  Br2 + SO2 + 2H2O 11. Ag+ + Br–  AgBr  (pale yellow) ; NaBr + Na2CO3  No reaction. 2NaBr + 2H2SO4  Br2  (reddish brown) + SO2 + SO42– + 2Na+ + 2H2O. 12. 3AgCl + Na3AsO3  Ag3AsO3  (yellow) + 3Cl– + 3Na+. AsO43– + 3Ag+  Ag3AsO4  (brownish-red). 15. 2NO3– + 4H2SO4 + 6Fe2+  6Fe3+ + 2NO + 4SO42– + 4H2O. Fe2+ + NO + SO42–  [Fe(NO)]2+SO42–. 5Cl2 (excess) + I2 + 6H2O  2HIO3 (colourless) + 10HCl Ag+ + Cl–  AgCl  (white) [Co(NO2)6]3– + 3NH4+  (NH4)3 [Co(NO2)6]  (yellow). 25. NH4+ + OH–  NH3  + H2O. (A) NH3, alkaline in nature turns red litmus blue; NH3 + HCl  NH4Cl (white fumes) (NH ) NO  Hg  Hg (B) 2Hg NO3 + 2NH    2   3   + NH4NO3 3 black  [Cu(NH3)4] SO4 (intense blue) CuSO4 + 4NH 3 (C) 2K2 (Hg4) + NH3 + 3KOH  HgOHgNH2 (brown) + 7K + 2H2O 28. Pb2+ + H2S  PbS  (black) + 2H+ ; 3PbS + 8HNO3  3Pb(NO3)2 + 2NO  + 3S + 4H2O. Pb2+ + SO42–  PbSO4  (white). 30. Pb(NO3)2 + 2NH4OH  Pb(OH)2 (white) + 2NH4NO3 Pb(NO3)2 + 2NaCl  PbCl2 (white) + 2NaNO3 Pb(NO3)2 + H2S  PbS (black) + 2NaNO3 31 AgCl + 2CN–  [Ag(CN)2]– + Cl– ; AgCl + 2S2O32–  [Ag(S2O3)2]3– + Cl–. AgCl + 2NH3  [Ag(NH3)2]+ + Cl–. AgCl is soluble in concentrated solution of KCl. AgCl + Cl–  [AgCl2]– (soluble complex) 32. HgI2  (red) + 2I–  [HgI4]2– (soluble colourless complex) ; BiI3 (black) + I–  [BiI4]– (soluble orange complex). 34. Pb2+ + CrO42–  PbCrO4  (yellow) ; PbCrO4  + 4OH  [Pb(OH)4] + CrO4 . – 2– 2– 52. Fe3+ + 3SCN–  Fe(SCN)3 (deep red colouration) amyl alcohol [Co(SCN) ] 2– Co 2+ + 4SCN – 4 (blue colouration) Cu2+ + 2SCN–  Cu(SCN)2 (black) ; 2Cu(SCN)2  2CuSCN(white) + (SCN)2. 36. H2S 2H+ + S2– ; HCl H2+ + Cl–. Due to common ion effect, the ionisation of H2S is suppressed and thus low concentration of S2– ions is obtained. This much of S2– ions concentration is enough to precipitate only IInd group cations (because of the low KSP of IInd group sulphides). 53. Fe2+ + [Fe(CN)6]4–  white precipitate ; Fe3+ + [Fe(CN)6]4–  Prussian blue precipitate. Zn2+ + [Fe(CN)6]4–  Bluish white/white precipitate ; Cu2+ + [Fe(CN)6]4–  chocolate brown precipitate Ag+ + [Fe(CN)6]4–  white precipitate ; Ca2+ + K4[Fe(CN)6]  white precipitate. 40. (A) Hg2+ + Co2+ + 4SCN–  Co[Hg(SCN)4 (deep blue) ; 54. Zn2+ + 2NH4OH  Zn(OH)2 (white) + 2NH4+ ; (B) 2Hg2+ + Sn2+ + 2Cl–  Hg2Cl2 (white) + Sn4+ ; Zn(OH)2 + 4NH4OH  Zn(NH3)4 + 6H2O Hg2Cl2 + Sn2+  Hg  (black) + Sn4+ + 2Cl– Zn2+ + S2–  ZnS (white) (C) 2Hg 2+ + NO 3 – + 4NH 3 + H 2 O  HgO.Hg(NH2)NO3 (white) (D) KCN no effect i.e. no reaction. 42. (A) Bi + 3I  BiI3  (black) 3+ – (B) 2Cu2+ + 5I–  Cu2I2 (white) + I3– (brown solution) (C) Pb2+ + 2I–  PbI2  (yellow) (D) Hg22+ + 2I–  HgI2 (red/scarlet) 44. (A) Cu2+ + S2–  CuSblack , (C) Zn2+ + S2–  ZnS (white) , (D) 2Fe3+ + H2S  2Fe2+ + 2H+ + S (milky white) 45. 2CuSO4 + 4KI  2CuI  (white) + 2K2SO4 + I2 3SCN– + Cu2+  CuSCN  (white) + (SCN)2 6CN– + Cu2+  [Cu(CN)4]3– + (CN)2 47. Both dissolves in acids. Cr(OH)3 is partially soluble while Fe(OH)3 is not soluble in aqueous NH3. Only Cr(OH)3 not Fe(OH)3 is soluble by NaOH/H2O2 according to the reaction. Cr(OH)3  (green) CrO 2– 4 (yellow solution) + H2O. 50. Fe3+ + [Fe(CN)6]3–  Fe[Fe(CN)6] brown colouration 3Fe3+ + 6CH3COO– + 2H2O Na2B4O7   Na2B4O7 + 10H2O ; 2NaBO2 + B2O3 CuO + B2O3 Cu(BO2)2 (copper (II) metaborate) blue bead in oxidising flame. 58. 2CoS + 6HCl + 2HNO3  3CoCl2 + 2NO + 3S + 4H2O CoCl2 + 6NaHCO3  Na4 [Co(CO3)3] + 2NaCl + 3H2O + 3CO2 2Na4 [Co(CO3)3] + Br2  2Na3 [Co(CO3)3] + 2NaBr (Green) 60. (A) Zn(OH)2  + 2OH–  [Zn(OH)4]2– (B) Cd2 + S2–  CdS (yellow) , NaOH/ H2O2  56. Na2B4O7.10H2O [Fe3(OH)2(CH3COO)6]+ + 2H+. (B) Zn(OH)2  + 2H+ Zn2+ + 2H2O (C) & (D) White precipitate of Zn(OH)2 dissolves in excess of ammonia solution and in solutions of ammonium salts owing to the production of tetraamminezincate(II). Zn(OH)2  + 4NH3 [Zn(NH3)4]2+ + 2OH– 61. Strontium chloride gives crimson colour flame in Bunsen burner. BaCl2 -apple green, CaCl2 -brick red, KCl - lilac(violet). 63. (A) titan yellow is absorbed by magnesium hydroxide producing a deep-red colour or precipitate. (B) Mg2+ + NH3 + HPO42–  Mg(NH4)PO4  (white). (C) Blue lake is formed by the adsorption of reagent on Mg(OH)2. 64. Ba2+ + CrO42–  BaCrO4  (yellow) ; Ag+ + Br–  AgBr  (pale yellow). SALT ANALYSIS AND QUALITATIVE ANALYSIS 66. BaCl2 + 2AgNO3  2AgCl (white) + BaNO3 BaCl2 + H2SO4  BaSO4(white) + 2HCl 67. (A) Pb(NO3)2 + 2NaCl  PbCl2 (white) + 2NaNO3 Ba(NO3)2 + 2NaCl  BaCl2 + 2NaNO3 ; BaCl2 is soluble in water (B) Na2SO4 gives white precipitate of PbSO4 and BaSO4 with Pb(NO3)2 and Ba(NO3)2 respectively. (C) Disodium hydrogen phosphate gives white precipitate with both salts. HPO4 + Ba 2– 2+ HPO4 + Pb 2 2+  BaHPO4  (white) ;  PbHPO4 (white) (D) Pb2+ + CrO42–  PbCrO4  (yellow) ; Ba2+ + CrO42–  BaCrO4  (yellow) Dil. HCl 69. (A) Hg22+ NH3(aq) Hg2 Cl2  (white) Hg  (black) + Hg(NH 2 )Cl  (white) . 1 4 4 4 4 4 44 2 4 4 4 4 4 4 43 Ag Bright yellow precipitate BaCl2 (aq) (AgCl) White ppt. Cl NH2 NH3(aq) Ag2O [Ag(NH3)2]Cl Brown/Black precipitate Colourless solution  (white) + Hg (black) + NH4Cl                 black Hg2 + 2I  Hg2I2  (green) 2+  2Cu (red and opaque) + 2Na2B4O7 + 2CO  77. Both belong to same group i.e. IInd group and their KSP values are low ; so both are precipitated according to the following reactions. 2Bi3+ + 3S2–  Bi2S3  (black). Sn4+ + 2S2–  SnS2  (yellow). 83. As it provides NH4+ ions which suppresses the ionisation of NH 4OH so that only the group 3 rd cations are precipitated as hydroxides because of their low solubility products and NO3– ions do not produce precipitate with the cations of IVth, Vth and VIth groups. 84. [Fe(CN)6]4– + NO3– + 4H+  [Fe(CN)5(NO)]2– + NH4+ + CO2 (C) Fe3+ + 3SCN–  Fe(SCN)3 deep red colouration 89. 4Zn + 10H+ + NO 3–  4Zn2+ + NH4+ + 3H2O. NaOH(aq) 71. Hg2Cl2 + 2NH3  Hg 2Cu(BO2)2 + 4NaBO2 + 2C (B) 2Fe3+ + 3S2–  2FeS (black) + S AgNO3 (aq) (X) 70. 2NaBO2 + B2O3 Cu(BO2)2  86. (A) 2Fe3+ + H2S  2Fe2+ + 2H+ + S (white) Black KI(aq) 76. Na2B4O7  CuO + B2O3 – 72. (A) Pb2+ + H2S  PbS  (black) + 2H+. (B) Cr2O72– + 3H2S + 8H+  2Cr3+ (green colour solution) + 3S  + 7H2O. (C) S 2– + [Fe(CN) 5NO] 2–  [Fe(CN) 5NOS] 4– (purple colouration). Reactions : Na2SO4 + BaCl2  BaSO4  + NaCl. Fuse BaSO4 + 4C + Na2CO3   Na2S + BaCO3  + 4CO . Na2S + H2SO4  Na2SO4 + H2S. Zn2+ + 2OH–  Zn(OH)2  (white) ; Zn(OH)2 + 2OH–  [Zn(OH)4]2–. [Zn(OH)4]2– + H2S  ZnS  (white) + 2OH– + 2H2O. 92. Ni2+ and Fe2+ both on reaction with alkaline solution of dimethyl glyoxime give red precipitate and red solution respectively but not zinc. 94. Ba2+ + CrO42–  BaCrO4  (yellow) ; Ba2+ + SO4  BaSO4 (white). Ba2+ + 2Cl–  BaCl2 (soluble in water). Ksp of SrCrO4 is high in acetic acid, so no precipitate is formed. Lead carbonate and basic lead carbonate both gives precipitate with K2CrO4 and NaCl. 95. Cl– + H2SO4  HCl  (colourless) + HSO4– MnO(OH)2 + 2H2SO4 + 2Cl –  Mn2+ + Cl 2  (yellowish green) + 2SO42– + 3H2O Cl2 + H2O  2HCl + [O] Litmus + [O]  colourless oxidised form Cl2 is a yellowish green gas which bleaches litmus paper by oxidation. 96. CrO2Cl2 + 2H2O  H2CrO4 + 2HCl 106. Pb2+ + 2Cl–  PbCl2 (white) ; H2CrO4 + (CH3COO)2Ba  BaCrO4 (Yellow) + 2CH3COOH 97. 5Cl2 + I2 + 6H2O  2HIO3 (colourless) + 10HCl Br2 + Cl2 2BrCl (pale yellow) 5SO32– + 2MnO4– + 6H+  2Mn2+ + 5SO42– + 3H2O 99. Nitrite ion liberates I2 from potassium iodide turning starch blue. 2NO 2 + 3I + 4CH 3COOH  I 3 + 2NO + 4CH3COO– + 2H2O – PbCl2 + H2S  PbS (black) + 2HCl PbS + 4H2O2  PbSO4 (white) + 4H2O PbSO 4  + 2CH 3 COONH 4  (NH 4 ) 2 SO 4 + (CH3COO)2Pb 98. SO32– reduces KMnO4 to colourless Mn2+ – PbCl2 + 2Cl–  [PbCl4] 2–(colourless soluble complex) 107. Marble (CaCO3) do not react, adsorb, absorb or dissolve Br2. As such there is no change in colour of Br2. Remaining dissolves or absorb or adsorb bromine. 108. Hg2Cl2 + 2NH3  – I2 + starch  blue colour 100. NO3 gives NO2 with concentrated H2SO4 which on passing through water form colourless HNO3() and HNO2(). Br– + MnO2 on heating with concentrated H2SO4 gives Br2 gas which on passing through water imparts it a reddish brown colour. – 101. Ag3PO4 is yellow precipitate which is soluble both in dilute ammonia solution and dilute HNO3. HPO42– + 3Ag+  Ag3PO4 + H+ Ag3PO4 + 2H+  H2PO4– + 3Ag+; Ag3PO4 + 6NH3  3[Ag(NH3)2]+ + PO43– Pale yellow precipitate of AgBr is not soluble in dilute HNO3; bright yellow precipitate of AgI is not soluble in both; Ag2CrO4 is obtained as red precipitate. 102. HgCl2 fails to give positive chromyl chloride test because of its covalent nature i.e., it does not dissociate to give Cl. 103.NaCl + AgNO3  AgCl  (white) + NaNO3 ; Ag2S  (black). Ag2CO3 and Ag2SO3 dissolves in dilute HNO3 liberating CO2 and SO2 respectively. Both Ag2CO3 and Ag2SO3 are white. AgCl is white but insoluble in dilute HNO3. NaCl solution is neutral to litmus as it is a salt of strong acid and strong base. 104. PbI2 is yellow (known as golden spangles). 105. AgBr has the highest solubility in 10–3 M NH4OH AgBr dissolves in all other solvents poorly. Cl Hg NH2  (white) + Hg (black) + NH4Cl 1 4 4 4 44 2 4 4 4 4 43 B la c k 109. The white precipitate obtained with H2SO4 is that of PbSO4. The white crystalline substance may be that of Pb(NO3)2. Pb2+ + S2–  PbS  (black) ; 3PbS  + 8HNO3  3Pb2+ + 6NO3– + 3S  + 2NO + 4H2O Pb2+ + SO42–  PbSO4  (white) PbSO 4 + 2CH 3COONH 4  (CH 3COO) 2Pb + (NH4)2SO4 BaS and SrS precipitates are not black in colour. Ag2SO4 is white precipitate but does not dissolve in ammonium acetate. 110.Ag+ + 2Cl–  [AgCl2]– (soluble complex) ; Ag+ + Cl– (dilute HCl)  AgCl (white) 2Ag+ + CrO42–  Ag2CrO4(red) ; Ag2CrO4 + NH3  2[Ag(NH3)2]+ + CrO42– 3Ag+ + HPO42–  Ag3PO4 (yellow) + H+ ; Ag3 PO4 + 6NH3   [Ag(NH3)2 ]+ + PO43– 111. (A) Both are red precipitates (B) 2Pb2+ + H2S (not in excess) + 2Cl– (from saturated KCl solution)  Pb2SCl2 (red) + 2H+ Hg2+ + 2–  Hg2  (red) (C) BiOI (orange) and Cu2[Fe(CN)6] (brown) 112.Both Cd2+ and Sn2+ are precipitated as yellow sulphides in the presence of dilute HCl. SALT ANALYSIS AND QUALITATIVE ANALYSIS 113.(A) Bi3+ + 3NH4OH  Bi(OH)3 (white) + 3NH4+ (B) Bi3+ + C6H3(OH)3  Bi(C6H3O3) (yellow) + 3H+ (C) Bi3+ + 3I–  BiI3 (black) ; BiI3 + I–  [BiI4]– (orange solution) (D) Bi + 3OH  Bi(OH)3 (white) ; 3+ – 2Bi(OH)3 + 3[Sn(OH)4]2–  2Bi(black) + 3[Sn(OH)6]2– 114.(A) As3+ + 3Zn + 3H+  AsH3  + 3Zn2+ ; 4AsH3  4As  + 6H2  (B) 4[Ag(NH3)2]+ + H2N–NH2.H2SO4  4Ag  + N2  + 6NH4+ + 2NH3  + SO42– (C) 2Ag2CrO4  + 2H+ 4Ag+ + Cr2O72– + H2O Ag2CrO4  + 4NH3 116.Cd + H2S  CdS + 2H , reaction is reversible; if the concentration of strong acid in the solution is above 0.5 M, precipitation is incomplete. Concentrated acid dissolves the precipitate for the same reason. + ; Cu2+ + 3CN–  CuCN  + (CN)2 118.Cu2+ + 2SCN–  Cu(SCN)2 (black) 2Cu(SCN)2  2CuSCN (white) + (SCN)2 Cu2+ + H2S H + FeCl3 + 3NH4SCN Fe(SCN)3(blood red colour) + 3NH4Cl. Ag+ + SCN–  AgSCN  (white). Co2+ + 4SCN– + Hg2+  Co[Hg(SCN)4]  (deep blue). 121. (A), (B) and (C) all gives blue colouration in solution or blue precipitate. (D) AgCl  + 2NH3  [Ag(NH3)2]+ Cl– (colourless solution) 122. CrO42– + 2H+ + 2H2O2  CrO5 (chromium peroxide) + 3H2O It in etherial layer develops blue colouration. 123. Mn(OH)2 + 2HNO3  Mn(NO3)2 + 2H2O. 115.The filter paper ash test is substitute for cobalt nitrate charcoal cavity test. Double oxide ZnO.CoO formed is green in colour. It is called Rinmann's green. 117.2Cu2+ + 4I–  Cu2I2 + I2 Cu2+ + 3SCN–  CuSCN (white) + (SCN)2 . 2[Ag(NH3)2]+ + CrO42– So, all statements are correct. 2+ 120. CoCl 2 + 4NH 4SCN (NH 4)2 [Co(SCN) 4] (blue colour in ethereal layer) + 2NH4Cl. CuS (black) + 2H+ 2CuS + 8CN–  2[Cu(CN)4]3– + S22– 119.Function of strong electrolyte NH4Cl is to suppress the ionisation of NH4OH so that the concentration of OH– ions in the solution is decreased but it is sufficient to precipitate the third group basic radicals because the solubility product of group III hydroxides is lower than IV, V and VI group hydroxides. The Cr(OH)3 is slightly soluble in excess of precipitant, upon boiling the solution, Cr(OH)3 is precipitated. 2Mn(NO 3 ) 2 + 5PbO 2 + 6HNO 3  2HMnO 4 (red – violet or purple colour) + 5Pb(NO3)2 + 2H2O. 124.(i) Mn2+ + 2OH–  2Mn(OH)2 (white) 2Mn(OH)2 + O2  MnO(OH)2 (brown) (ii) Mn2+ + 2NH3 + 2H2O Mn(OH)2 + 2NH4+ with NH4+ the reaction proceeds towards the left. (iii) 2Mn2+ + 5S2O82–  2MnO4– + 10SO42– + 16H+ 125. In first step with H2S gas in acidic medium Cd2+ and Cu2+ will precipitate as CdS and CuS respectively. Thus the filtrate will now contain chromium, iron and aluminium. In second step with NH4Cl and NH4OH, Cr3+, Fe3+ and Al3+ will precipitate out as their hydroxides. In third step on addition of excess of NaOH, Al(OH)3 and Cr(OH)3 precipitates will dissolve forming soluble complexes but Fe(OH)3 precipitate is unaffected. Hence the filtrate will contain Na[Al(OH)4] and Na[Cr(OH)4]. Al(OH)3 + OH–  [Al(OH)4] – (colourless solution); Cr(OH)3 + OH– 126. 3Na2O2 + 2Cr(OH)3 [Cr(OH)4] – (green solution)  2NaOH + 2H2O + 2Na2CrO4 (yellow) 127. On adding H2O2 in alkaline medium or SnCl2 solution in acidic medium, the [Fe(CN)6]3– part of the compound is reduced and prussian blue is precipitated. 128. (A) Zn(OH)2 + 2OH– [Zn(OH)4]2– (B)and (C) Zn(OH)2 + 4NH3 [Zn(NH3)4]2+ + 2OH– or NH4+ 129. Ba2+ salts gives yellow precipitate with K2CrO4 solution and this precipitate is not soluble in CH3COOH. Ba2+ ions gives apple green colour in the flame test. 130. (B) BaCO3 + ZnS mixture dissolves in HCl but is insoluble in water. Further the solution in HCl will be colourless due to the formation of soluble BaCl2 and ZnCl2. 131. (A) No precipitate with K2CrO4 in acetic acid as its ksp is high. (B) Ca2+ + 2K+ + [Fe(CN)6]4–  K2Ca[Fe(CN)6] (white) (C) It imparts brick red colour to Bunsen flame. (D) Ca(HCO3)2 is formed which is water soluble. EXERCISE - 2 Part # I : Multiple Choice 4. (A) Na2S + H+  H2S  + 2Na+. ; (A) AgCl dissolves completely forming [Ag(NH3)2]Cl ; AgCl + 2NH4OH  [Ag(NH3)2]Cl + 2H2O. (B) AgBr dissolves completely forming [Ag(NH3)2] Br soluble complex. AgBr + 2NH4OH  [Ag(NH3)2]Br+ 2H2O. (C) Ag2CrO4 + 4NH3  2[Ag(NH3)2]+ + CrO42– (D) AgI is insoluble in concentrated aqueous NH3. 11. (A) Ag+ 2CrO42–  Ag2CrO4  (red) [X]. (B) Ag2CrO4 + 4NH3  2[Ag(NH3)2]+ + CrO42– . (C) Cr3+ + 3OH–  Cr(OH)3  (green). Cr(OH)3 + OH–  [Cr(OH)4]– (green coloured soluble complex). 4 6 7 (D) 3 S O2 + C r2O72 – + 2H+  2Cr3+[Y] + 3 SO 24– + H2O. 13. (A) Fe2+ responds to this test but not Fe3+; Fe(II) gives soluble red iron(II) dimethylglyoxime in alkaline solution. Na2SO4 gives no reaction with H2SO4. (D) Ag2O  + 4NH3 + H2O  2[Ag(NH3)2]+ + 2OH– (B) 2MnO4– (pink solution) + 5H2S + 6H+  2Mn2+ (colourless) + 5S  + 8H2O. Ag2O  + 2H+  2Ag+ + H2O (B) and (C) are correct statements. No colour change is observed with Na2SO4. (C) S 2– + [Fe(CN) 5NO] 2–  [Fe(CN) 5NOS] 4– (purple or violet colouration). No colour change is observed with Na2SO4. (D) S2– + Cd2+  CdS  (yellow). Na2SO4 forms CdSO4 which is water soluble. 5. 9. (A) Br– + H+  HBr  ; 2HBr + 2H2SO4  Br2  (reddish brown) + SO2  + SO42– + H2O. (B) 4NO3– + 2H2SO4  4NO2  (reddish brown) + O2  + 2SO42– + 2H2O. (C) SO32– + 2H+  SO2  (colourless) + H2O. (D) 3I + 2H2SO4  I3–  (violet/purple) + SO42– + 2H2O + SO2. – 14. (A) Red colour solution or precipitate is produced when reagent reacts in alkaline solution. (B) HO.SO2.NH2 + HNO2  N2 + 2H+ + SO42– + H2O. (C) Fe2+ + [Fe(CN)6]3–  Fe3+ + [Fe(CN)6]4–. 4Fe3+ + [Fe(CN)6]4–  Fe4[Fe(CN)6]3  (Turnbull's blue). (D) 4Cr(OH)3  + 5O22–  4CrO42– (yellow solution) + 6H2O. 15. (A) PbSO4 + H2SO4 (hot and concentrated)  Pb2+ + 2HSO4– (soluble) (B) It dissolves forming Na2[Pb(OH)4] soluble complex. 16. B4O72– + 4Ag+ + H2O  4AgBO2 (white) + 2H+ 2AgBO 2 + 3H 2O Hydrolysis /H2O Ag 2O (brown) + 2H3BO3 SALT ANALYSIS AND QUALITATIVE ANALYSIS 17. CuS dissolves in 50% HNO3 ; 3CuS + 8HNO3  3Cu2+ + 6NO3– + 3S + 2NO + 4H2O But NiS, CoS and HgS do not dissolve in 50% HNO3 and dissolve in aquaregia forming their chlorides. 29. (A) 5SO2 + 2IO3– + 4H2O  I2 + 5SO42– + 8H+ ; I2 + starch  blue colour.. (B) 2H+ + 3SO2 + Cr2O72–  2Cr3+ (green) + 3SO42– + H2O 21. (A) Correct. (C) Pb2+ + SO32–  PbSO3  (white) (B) Cu2+ + 2CN–  Cu(CN)2 (yellow) ; (D) SO2 + 2H2O + Cl2  H2SO4 + HCl 2Cu(CN)2  2Cu(CN)2 (white) + (CN)2 (C) BiI3 + H2O boiled BiOI (orange) + 2HI (D) Bi(OH)3  HCl + NH3  NH4Cl BiO.OH (yellowish white) + H2O 22. (NH4)2 CO3 and (NH4)2 SO4 can not be used as they would also precipitate the IV and Vth group cations. 23. (A) Cr3+ + 3NH3 + 3H2O  Cr(OH)3 + 3NH4+ The reaction is reversible; on addition of NH4+ , shifts to backward direction. Thus if excess of NH4+ salt is added, then precipitation of Cr(OH)3 will not take place. However, because of very small ksp of iron (III) hydroxide complete precipitation will take place even in the presence of ammonium salts. (ksp = 3.8 × 10–38) (B) Concentration of CO32– provided by Na2CO3 in aqueous solution is just sufficient to precipitate Mg2+ ion as MgCO3 along with Ba2+ , Ca2+ and Sr2+ as their carbonates. (C) The oxidising anions like MnO4–, Cr2O72–, ClO4–, etc., also respond to this test. Ni + H2SO4 + 2H+  Ni2+ + SO2 [X] + 2H2O With dilute H2SO4, hydrogen gas is liberated. 30. BF3 colour the flame green ; B(OC2H5)3 burns with green edged flame ; Barium chloride (volatile) gives apple green colour to flame. 31. Co2+ + 7NO2– + 3K+ + 2H+  K3[Co(NO2)6]  (yellow) + NO  + H2O. So [X] is K3[Co(NO2)]6. It is called Fischer's reagent ; [Co(III)(NO 2 ) 6] 3– has d 2 sp 3 hybridisation and is diamagnetic. It's IUPAC name is potassium hexanitrito – N – cobaltate(III). Part # II : Assertion & Reason 2. Ba(OH)2 + CO2  BaCO3 (white) + H2O; (D) CrO2Cl2 + 2H2O  H2CrO4 (aq) + 2HCl. BaCO3 + H2O + CO2  Ba(HCO3)2 24. Co + 2CN  Co(CN)2 (reddish - brown) 2+ – Statement-2 : 2Ag+ + CO32–  Ag2CO3 (white) ; Co(CN) 2  + 4CN – (excess)  [Co(CN) 6 ] 4– (brown solution) [Co(CN)6]4– + 4H+  Co(CN)2  + 4HCN.  Ag2CO3   Ag2O (brown)+ CO2 3. 25. (A) Cu2 [Fe(CN)6] ; K2 Zn3 [Fe(CN)6]2 ; (C) Ag4[Fe(CN)6] ; K2Zn3 [Fe(CN)6] ; (D) Th[Fe(CN)6] ; Cu2[Fe(CN)6] 5. 26. (A) Hg2+ + Co2+ + 4SCN–  Co[Hg(SCN)4] (deep blue) (B) Soluble in NaOH forming [Al(OH)4]–, not in NH3 (aq) [Cr(OH) 4 ] – (green solution) (D) Correct statement. 27. Iron and NO exist as Fe(II) and NO+ respectively. 28. Cr = Green ; Co = Blue. Statement-1 : Ag2SO3  + SO32–  2[Ag(SO3)]– (soluble complex) Statement-2 : 5SO32– + 2MnO4– (pink) + 6H+  2Mn2+ (colourless) + 5SO42– + 3H2O (B) Fe4 [Fe(CN)6]3 ; K2Ca [Fe(CN)6] (C) Cr(OH) 3  (green) + OH – Statement-1 : Statement-1 : Zn2+ + H2S ZnS + 2H+ ; H 2S 2H+ + S2– Sulphide ion concentration obtained from the H2S is depressed so much by the hydrogen-ion concentration from acid that it is too low to exceed the solubility product of ZnS and consequently precipitation ceases. Statement-2 : ZnS is insoluble in caustic alkali solution, but dissolves according to the following reaction in dilute HCl. ZnS + 2HCl  ZnCl2 + H2S. 7. Statement-1 : In the presence of NH 4+ salts, no precipitation of Mg2+ occurs because the equilibrium (B) Cr3+ metaborate  Green Cr3+ + 3OH–  Cr(OH)3 (green) NH4+ + CO32– NH3 + HCO3– is shifted towards the formation of HCO3– ions. Ksp of the precipitate being high (K sp of pure MgCO 3 is 1 × 10–5 ), the concentration of carbonate ions necessary to produce a precipitate is not attained. Statement-2 : NH4OH turns red litmus blue. NH4OH 9. Cr(OH)3 + OH–  [Cr(OH)4]– (green coloured soluble complex). [Cr(OH)4]– + H+  Cr(OH)3 + H2O Cr(OH)3 + 3H+   Cr3+ + 3H2O NH4+ + OH– . (C) Al3 + 3OH–  Al(OH)3 (white) Statement-1 : Cu2+ + 6CN–  [Cu(CN)4]3– + (CN)2 ; Al(OH) 3 + OH–  [Al(OH)4] – (colourless soluble complex). Cd2+ + 4CN–  [Cd(CN)4]2– Statement-2 : [Cu(CN)4]3– being stable complex is not effected by H2S gas but [Cd(CN)4]2– is not so stable and gives yellow precipitate with H2S. [Al(OH)4]– + H+  Al(OH)3 + H2O Al(OH)3 + 3H+   Al3+ + 3H2O [Cd(CN)4]2– + H2S  CdS (yellow) + 2H+ + 4CN–. 12. Statement-1 : In presence of ammonium salts the reaction proceeds in backward direction forming ammonia gas. Statement-2 : Mg(OH)2 is insoluble in water. (D) Fe3+ metaborate  Pale yellow Fe3+ + 3CN–  Fe(CN)3 (reddish brown) Fe(CN)3  + 3CN–  Fe(CN)6]3– (yellow colour soluble complex). EXERCISE - 3 Part # I : Matrix Match Type 1. Fe3+ + 3OH–  Fe(OH)3  (reddish brown). (A) AgCl + Cl–  [AgCl2]– soluble complex. Part # II : Comprehension AgCl + 2NH3 [Ag(NH3)2]+ + Cl– Comprehension # 1 : AgCl + 2CN [Ag(CN)2] + Cl 1. – – – Sample NaCl AgCl is insoluble in dilute HNO3. Precipitate ‘A’ insoluble chloride (AgCl) + Filtrate (Ba2+ and Zn2+) (B) 2CuS + 8CN–  2[Cu(CN)4]3– + S22–. Na2SO4 3CuS + 8HNO3  3Cu2+ + 6NO3– + 3S + 2NO + 4H2O boiled for S + 2HNO3 longer 2H+ + SO42– + 2NO time (C) Zn(OH)2 + 2H+ Zn(OH)2 + 4NH3 ppt. ‘C’ insoluble hydroxide (Zn(OH)2) Filtrate (Zn2+ ) + ppt. ‘B’ insoluble sulphate (BaSO4) Zn2+ + 2H2O Ag+ + Cl–  AgCl (white) ; [Zn(NH3)4]2+ + 2OH– 3AgCl + Na3AsO3  Ag3AsO3 (yellow) + 3NaCl Zn(OH)2 + 2OH–  [Zn(OH)4]2– (D) BaCO3 + 2H+ Ba2+ + SO42  BaSO4 (white) ; Ba2+ salts give apple green colour to the Bunsen flame. Ba2+ + CO2 + H2O BaCO3 is slightly soluble in solution of ammonium salts of strong acids only. 3. Zn2+ + 2NH3 + 2H2O  Zn(OH)2 (white) + 2NH4 Zn(OH)2 + 4NH4 (A) Mn2+ meta borate  Amethyst red Mn2+ + 2OH–  Mn(OH)2  (white) Mn(OH)2  (white) + O2 (air)  2MnO(OH2)  (brown) aqueous NH3 3. [Zn(NH3)4]2+ + 2OH– (A) CoO . ZnO = Rinmann's green reagent used as green pigment. (B) BaSO4  + H2SO4 (conc.)  Ba2+ + HSO4– (C) 2AgCl  (white) h   2Ag  (black) + Cl2  SALT ANALYSIS AND QUALITATIVE ANALYSIS Comprehension # 2 : 3. 5. (A) Bi + 3 OH  Bi(OH)3  ; 3+ Hg2Cl2 + 2NH3  – Hg (black) + Hg(NH2)Cl (white) 2Bi(OH)3  + [Sn(OH)4]2–  2Bi  + 3 [Sn(OH)6]2– (B) is not correct as 'D' is precipitate of bismuth. (C) Bi3+ + C6H3(OH)3  Bi(C6H3O3 )  (yellow) + 3H+. (Black) 6. Bi3+ gives BiO+ ion and Sb3+ gives SbO+ ion. Bi3+ + Cl– + (D) Bi3+ + C9H7ON + H+ + 4I–  C9H7ON. HBiI4  (red) 4. (A) Cl– + Ag  AgCl  (white) ; 3AgCl + AsO33–  Ag3AsO3  (yellow) + 3Cl– (B) Bi3+ + 3OH–  Bi(OH)3 (white) ; H2O  BiO.Cl  + 2H+. 7. 1. 3Zn2+ + 2K+ + 2[Fe(CN)6]4–  K2 Zn3 [Fe (CN)6]2  2. (i) Mg2++ NH3 + HPO42–  Mg(NH4) PO4  (white) 8. H2S + [O]  H2O + S  (white) (HNO3 is strong oxidising agent). CuSO4 + H2S  CuS  + H2SO4. 3CuS + 8HNO3  3Cu2+ + 6NO3– + 3S  + 2NO  + 4H2O. Zn(OH)2 + 4NH4OH  [Zn(NH3)4] (OH)2 + 4H2O (iii) Bi3+ + 3–  Bi3  (black).  2NO32– + Cu2+ + 4NH4OH  [Cu(NH3)4]2+(NO3)2 BiO  (orange) + 2H+ + 2–. (intense blue coloured solution) + 4H2O ; (iv) Na2HPO4 + 12 (NH4)2 MoO4 +23 HNO3  [Cu(NH3)4](NO3)2 + K4[Fe(CN)6]  Cu2[Fe(CN)6]  (chocolate brown). (NH4)3 PMo12 O40  + 2NaNO3 + 21NH4NO3 + 12H2O (canary yellow) 3. (i) 2Cu(BO2)2 (blue) + C  2CuBO2 (colourless) )+ B2O3 + CO 2Cu(BO2)2 + 2C  2Cu (red and opaque) + 2B2O3 + 2CO (ii) AgBr + 2NH3  [Ag(NH3)2] Br (iii) 2Cr(OH)3 + 2Na2CO3 + 3KNO3 2Na2CrO4+ 3KNO2 + 2CO2 + 3H2O (iv) 2Cu(NO3)2  2 CuO + 4NO2+ O2 4. 2NO2– + H2SO4  SO42– + 2HNO2 3HNO2  HNO3 + 2NO + O2 2NO + O  2NO2  (reddish brown) 2K + 2NO2  2KNO2 + 2 Starch + 2  blue CuS + H2SO4  CuSO4 + H2S. 2HNO3  2NO2 + H2O + [O] (ii) Zn2+ + 2NH4 OH  Zn(OH)2  (white) + 2NH4+ Bi3  + H2O (i) Na2S + CdCO3  CdS  (yellow) + Na2CO3 (ii) CoCl2 + 4NH4 SCN (NH4)2 [Co(SCN)4] (blue colour in etherial solution) + 2NH4Cl Bi(OH)3  BiO.OH (yellowish-white) + H2O (C) BiOCl  (white) + 2H+  Bi3+ + H2O + Cl– EXERCISE - 4 Subjective Type + NH4+ + Cl–. Ba2+ + CuSO4  BaSO4  (white) + Cu2+ . 9. A - FeSO4.7H2O ; B - BaSO4  ; C - SO2 ; D - SO3 E - Fe2O3 ; F - FeCl3 ; G - Fe(SCN)3 10. (i) CuCO3 (A) (ii) CuO (B) + H2 (iii) 2Cu 2+  CuO (B) + CO2 (C) ;  + Cu  (D) + H2O [Fe(CN) 6 ] 4–  2Cu2[Fe(CN)6]  (chocolate brown) (E) (iv) CO2 + Ca(OH)2  CaCO3  + H2O ; CaCO3 + H2O + CO2  Ca(HCO3)2 (soluble) 11. This gives black cobalt oxide, Co3O4 , upon ignition and this mask the colour of thernad blue (CoAl2O4). 12. CrO2Cl2 + 4NaOH  Na2CrO4 (A) + 2NaCl + 2H2O (E) Ni(OH) 2  (green) + 6NH3  [Ni(NH3)6]2+ (deep blue colouration) + 2OH– Na2CrO4 + H2SO4  2Na2 Cr2 O7 (B) + Na2 SO4 + H2O (F) Zn3(PO4)2  (white) + 12NH3  3[Zn(NH3)4]2+ + Na2Cr2 O7 + 2NaOH  2Na2CrO4 (C) + H2O Na2CrO4 + 2AgNO3  Ag2 CrO4 (D) + 2NaNO3 13. ZnS + H2SO4  ZnSO4 + H2S. Cr2O72– + 3H2S + 8H+  2Cr3+ (green solution) + 3S  + 7H2O. S + O2  SO2 ; 2H2S + SO2  2H2O + 3S. Zn2+ + 2OH–  Zn(OH)2  (white) ; Zn(OH)2 + 2OH–  [Zn(OH)4]2– . Zn + 2NH3 + H2O 2+ Zn(OH)2  + 4NH3 14. CH3 – C = N Zn(OH)2  (white) + NH4 . + [Zn(NH3)4]2+ + 2OH–. 15. (i) FeCl3 + 3H2O  Fe(OH)3  (reddish brown) + 3HCl ; so solution is acidic in nature. (ii) Fe + 3SCN  Fe(SCN)3 (red colouration). – 4Fe3+ + 3[Fe(CN)6]4–  Fe4[Fe(CN)6]3 (Prussian blue). (iii) Cr2O72– + 4Cl– 6H+  2CrO2Cl2  (deep red) + 3H2O. (iv) CrO2Cl2  + 4OH–  CrO42– + 2Cl– + 2H2O. Pb + CrO  PbCrO4  (yellow). 16. (a) Violet (or blackish–purple) precipitate consisting of Zn[Hg(SCN)4] and Cu[Hg(SCN)4] is formed. (b) Zn2+ + [Hg(SCN)4]2–  Zn [Hg(SCN)4]  (white). 17. (A) Ag2CrO4  (yellow) + NH3  [Ag(NH3)2]+ + CrO42– (B) Cu(OH)2.CuSO4  (blue) + 8NH3  2[Cu(NH3)4]2+ + SO42– + 2OH– (C) PbSO3  (white) + 4OH  [Pb(OH)4] + SO3 Soluble in sodium hydroxide not in NH3. (D) Soluble in sodium hydroxide not in NH3. 2– [Ni(dmg)2]  (bright red). H3C – C = N +2 Ni N = C – CH3 N = C – CH3 rosy red ppt 19. Here NO is NO+; so in [Fe(H2O)5NO+]2+, the oxidation state of iron is +1. 20. NaCl-Golden yellow ; KCl-Lilac ; CuCl2-bluish-green, BaCl2-Apple green ; SrCl2-Crimson ; CaCl2-Brick red. 21. (i) 4Cl– + Cr2O72– + 6H+  2CrO2Cl2  (deep red) + 3H2O (ii) NO2– + H+  HNO2 ; 3HNO2  HNO3 + NO  + H2O 2NO  + O2   NO2  (brown) 2– 4 – NH 4OH O – H -------- O ions or NH4Cl and FeCl2 2+ 18. Ni2+ + 2dmg O -------- H – O The given unknown mixture contains NH4+, Fe2+ and Cl– 3+ 2PO43– (G) Insoluble in NH3, soluble appreciably in boiling concentrated H2SO4. (H) Bi(OH)2NO3 is insoluble in NH3. (I) Insoluble in NH3 but soluble in ammonium salts liberating NH3. 2– (iii) 3I– + 2H2SO4  I3–  (violet) + SO42– + 2H2O + SO2 (iv) 2KBr + 2H2SO4  Br2  (reddish brown) + SO2  + NO42–+ 2K+ + 2H2O – (v) Cl– + H2SO4  HCl  (colourless) + HSO4 Br 2   (vi) 2KBr + MnO 2 + 2H 2 SO 4 (reddish-brown) + 2K + Mn + 2SO4 + 2H2O + 2+ 2– (vii) 4NO3– + 2H2SO4  Br2  (reddish-brown) + 2K+ + Mn2+ + 2SO42– + 2H2O (viii) KCl + MnO(OH)2 + 2H2SO4 + 2Cl– (brown)  Mn2+ + Cl2  (yellowish green) + 2SO42– + 3H2O (ix) SO32– + 2H+  SO2  (colourless) + H2O SALT ANALYSIS AND QUALITATIVE ANALYSIS 22. (1) Al 3+ and Hg 2+ + H H2S HgS  (black) + Al 3+ EXERCISE - 5 Part # I : AIEEE/JEE-MAIN (in solution) + H H2S (2) Cd2+ and Zn2+ CdS  (yellow) + Zn2+ 1. (in solution) (3) Fe 3+ and Cu 2+ + H H2S Methyl orange shows Red (pinkish) color in Acidic medium & yellow color in basic medium since original solution is basic so initial color  yellow CuS  (black) + Fe 3+ & Titrated with acid so (in solution). Final color  pinkish (red) Part # II : IIT-JEE ADVANCED 23. Pb2+ + 2Cl–  PbCl2  (white) ; Hg22+ + 2Cl–  Hg2Cl2  (white) 1. (soluble) Ag+ + Cl–  AgCl  (white) Ksp of chlorides of Pb2+ and Hg22+ is low as compared to Ksp of Hg2+ and Cd2+. Chloride ion concentration provided by dilute HCl is just enough to exceed the Ksp of PbCl2 and Hg2Cl2. Thus Pb2+ and Hg22+ are precipitated as their chlorides. 2. + 2OH– Co(CN)2+ 4CN–  [Co(CN)6]4– (brown solution) or Zn(OH)2 + 4NH4OH + H2O + O 2  4[Co(CN)6] (yellow solution) + 4OH– NH4Cl [Zn(NH3)4]2+ + 4H2O + 2OH–. But Al(OH)3 , Mg(OH)2 and Ca(OH)2 don’t dissolves in excess of NH3 solution. 4. Cu2+ + 6CN–  [Cu+(CN)4]3– + (CN)2 3– (v) Co2+ + 6HCO3–  [Co(CO3)3]4– + 3H2O + 3CO2 [Co(CO3)3]4– [Zn(OH)4]2– H2O-boiled Zn(OH)2 ¯ (white) + 2OH– Zn(OH) 2 precipitate is readily soluble in excess of ammonia and in solutions of ammonium salts due to the formation of tetraamminezinc(II). Zn(OH)2 + 4NH3  [Zn(NH3)4]2+ (soluble complex) CoS  (black) (iii) Co2+ + 2CN–  Co(CN)2 (reddish-brown) (iv) 4[Co(CN 6] Hg2+ gives red precipitate of HgI2 which dissolves in excess KI forming colourless [HgI4]2– ions. Pb2+ gives yellow precipitate of PbI2 . Cu2+ gives white precipitate of Cu2I2 with evolution of iodine. (ii) CoS+ HNO3 + 3HCl  Co2+ + S+ NOCl+ 2Cl– + 2H2O 4– MgCO3  (white) + H2O + CO2 BiI3 + I–  [BiI4]– (orange solution) 3. NH4OH/ NH4 Cl  Bi3+ + 3I–  BiI3  (black) ; 24. A red colouration is obtained. 25. (i) Co2+ + S2– Mg2+ + 2HCO3– (from sodium salt)  Mg(HCO3)2 [O] [Co(CO3)3]3– (green solution) Cu2+ + 2CN–  Cu(CN)2  (yellow);2Cu(CN) 2   2CuCN  (white) + (CN)2  CuCN  + CN–  [CuI(CN)4]3– (colourless soluble complex). 5. MgSO4 on reaction with Na2HPO4 in presence of NH4OH gives white precipitate of Mg(NH4)PO4. MgSO4 + Na2HPO4 + NH4OH  Mg(NH4)PO4  + Na2SO4 + H2O. 6. Hg2+ + 2I–  HgI2  (scarlet / red) HgI2 + 2I– (excess)  [HgI4]2– (soluble complex) Hg2+ + Co(SCN)2  Co[Hg(SCN)4]  (deep blue) 7. All ammonium salts on reaction with alkali produce ammonia. The nitrate and nitrite also on reduction with nascent hydrogen (produced by the reaction of zinc and sodium hydroxide) produce the ammonia gas according to the following reactions. 11, 12 & 13 Cu(M) + AgNO3(N) (aqueous colourless solution)  Resultant solution contains Cu(NO3)2 (blue solution) and AgNO3 (colourless solution) (N) Note : Here it is considered that complete AgNO3 is not utilized in the reaction. AgNO3 (aq)+ NaCl (aq) AgCl  (white ) (O) + NaNO3 Solution containing white ppt. of AgCl also contains Cu(NO3)2 which developed deep blue colouration with aqueous NH3 solution AgCl  (white) + 2NH3 (aq.)  [Ag(NH3)2]+ Cu(NO3)2 (aq.) + 4NH3 (aq.)  [Cu(NH3)4] (NO3)2 (deep blue solution) So, Metal rod M is Cu. The compound N is AgNO3 and the final solution contains [Ag(NH3)2]+ and [Cu(NH3)4]2+ NH4NO2 + NaOH  NaNO2 + NH3 + H2O NH4NO3 + NaOH  NaNO3 + NH3 + H2O Zn / NaOH NaNO2 + 6[H]    NaOH + NH3 + H2O 14. In presence of acidic medium, ionisation of H2S is suppressed so less number of S2– ions are produced. Zn / NaOH So only those sulphides are precipitated which have low solubility product (KSP) value, For example CuS and HgS. NaNO3 + 8 [H]    NaOH + NH3 + 2H2O So options (A) and (B) are correct. 15. Precipitation of insoluble cuprous salts pushes the equilibrium backwards (i.e. towards the left) 8 to 10 S2– (X) + 2 H+  H2S 16. + H2S (X) + + 6Fe3+ (Y)  6Fe2+ + NH4+ + 4H+ + (methylene (D) with NaOH K2Zn [Fe(CN)6] + NaOH  [Zn(OH)4]2– (aq) + [Fe(CN)6]4– (aq) 17. 8MnO 4  3S2 O 32  H 2 O  8MnO 2  6SO 24  2OH  blue). The compound X is Na2S and Y is FeCl3. SALT ANALYSIS AND QUALITATIVE ANALYSIS 22. (A) Cu2+ show characteristic green colour in the flame test. (B) Only Cu2+ can give precipitate in acidic medium on passing H2S (C) Both Cu2+ and Mn2+ show the formation of precipitate by passing H2S in faintly basic medium. (D) E o Cu 2 /Cu MOCK TEST 1. (A) H2S  + 3Zn2+ + 3H2O SO32+ + Zn + 8H+ PbS  (black) Pb2+ + S2– 2. (A) E o Mn 2 / Mn MgCl2 + 2NaHCO3 , as per electrochemical series.  Mg(HCO3)2 3. Mg(HCO3)2 (soluble)+2NaCl MgCO3  (white) + CO2 + H2O (B) CuSO4 + H2S CuS  (black) + H2SO4 CuS + 2HNO3 Cu(NO3)2 (blue solution) + NO + S + H2O Cu2I2  (white) + I2  2Cu2+ + 4I– (colour of solution is yellow/brown) 4. (D) Pb2+ + OH– Pb(OH)2  (white) ; Pb2+ + CO32– PbCO3  (white) Pb2+ + 2 Cl– Pb2+ (aq.)+ SO42– PbCl2  (white) ; PbSO4  (white) 5. (D) (A) (B) (C) can be precipitated by HCl as well as H2S as their insoluble chlorides and sulphides respectively. (D) Sn2+ + 2HCl SnCl2 (soluble) + 2H+. It can be precipitated only by H2S as its insoluble sulphide (brown). 6. (B) Bi (NO3)2 + KI Bil3 + KI KNO3 + Bil3  (black) K [BiI4] (orange) 7. (A) MnO4–/H+ [O] : Fe2+ [O] Fe3+ + [Fe(CN)6]4– Fe4[Fe(CN)6]3 8. (B) On adding HCl the equilibrium will shift in backward direction. 15. (A,B) 9. (A) ZnS & MnS are soluble in conc. HCl. Ni2+ & Co2+ are insoluble in conc. HCl but dissolves when KCIO3 is added, forming corresponding chlorides. Co(CN)2  (buff. coloured)+2KCI CoCl2 + 2KCN Co(CN)2 + 4KCN K4[Co(CN)6] (yellowish brown) Ni2+ forms white precipitate which is soluble in excess KCN. 10. (D) (A) H3PO2 + 2H2O H3PO4 + 4H HgCl2 + 2H Hg2Cl2  (white) + 2HCl Hg2Cl2 + 2H 2Hg  (grey) + 2HCl (B) HgCl2 + SnCl2 HgCl2 + SnCl2 Hg2Cl2  (white) + SnCl4 Hg  (grey) + SnCl4 (C) Red precipitate is formed which dissolves in excess of KI. (D) White precipitate of Hg(NH3)Cl is formed. MnS  (buff/light coloured) Mn + H2S 2+ HCl 16. (A, B, D) MnCl2 NaOH MnO2  (Brown/black) [O] MnO2 + 2KNO3 + Na2CO3 fusion Na2MnO4 (A) Bi3+ + 3NH4OH 11. (B) 4 Fe(OH)3  + 3 [Fe(CN)6] 4– 12. (B, C, D) (A) 2HCO3– + Mg2+  cold Mg(HCO3)2 (soluble) MgCO3  CO2 + 2H2O (NH4)2 CO3 + CaCO3  (B) Ca(HCO3)2 + 2NH3 (C) True statement Hg4O3CO3  (reddish brown) + 6H+ (D) CO32– + 4Hg2+ + 3H2O basic mercury(II) carbonate 13. (C,D) 2I– + Cl2 I2 (purple/violet) ; 2I– + Br2 I2 (purple/violet) Bi(OH)3 (white) + 3NH4+ (B) Pb2+ + 2NH4OH Pb (OH)2 (white) + 2NH4+ (C) Due to common ion effect of NH4+, the OH– ion concentration is not excess enough to precipitate Mg2+ as Mg(OH)2 because of its high solubility product. (D) Fe3+ + 3NH4OH Fe(OH)3 (reddish brown) + 3NH4+ (E) Cu2+ + 4NH3 [Cu(NH3)4]2+ In presence of ammonium salts, precipitation does not occur at all, but blue colour solution is formed right away. 18. (A,B,C,D) (A) CaSO4 + (NH4)2SO4 (NH4)2[Ca(SO4)2] (soluble) (B) BaCrO4 is insoluble in dilute acetic acid & thus gets precipitated with K 2CrO 4 (low K sp in K 2CrO 4 solution in acetic acid). (C) Cr(OH)3 is soluble in NaOH & Br2 water forming sodium chromate while Fe(OH)3 is insoluble. 14. (C, D) (C) Heavy metal chlorides like AgCl does not give chromyl chloride. (D) 2NaCl + MnO2 + 3H2SO4 (B) AlCl3 + K2Cr2O7 + H2SO4 Al2(SO4)3 + K2SO4 + CrO2Cl2  (deep red or orange red vapour) + H2O 17. (A, B, D) + KNO2 + 2NaOH + CO2 Fe4[Fe(CN)6]3 + 2 OH Al(OH)3 + 3HCl  (fumes) (D) Gives blue bead of Al2O3.CoO (green compound) – (A) AlCl3 + 3H2O 2 NaHSO4 + MnSO4 + Cl2 (D) [Cu(CN)4]3– is more stable than [Cd(CN)4]2– gives yellow precipitate with H2S. 19. (A) 20. (B) PbI2 + 2I– [PbI4]2- soluble complex Reaction is reversible and shifts in backward direction on dilution with water. SALT ANALYSIS AND QUALITATIVE ANALYSIS 21. (D) 28. (C) Dilute solution contains more of water thus precipitate formed gets dissolved. 22. (A) 4[Ag(NH3)2]+ + NH2 – NH2.H2SO4 (saturated solution) 4Ag + N2 + NH3 + 6NH4+ + 2NH3 + SO42– This is called silver mirror test. Finely divided silver metal adhere to the glass walls forming an attractive mirror. 23. (D) All are black and gives gas with dil. H2SO4 S2– + 2H+ Silver is precipitated. H2S  30. SO32– + H2SO4 24. (D) PbSO4 + 2CH3COO– (A) SO42– + (CH3COO)2 Pb 2K2SO4 + Cu2I2 + I2 (B) 2CuSO4 + 4KI (C) CuSO4 . 5H2O 29. (D) 2H2O CuSO4 .3H2O 25. (D) SO42– + SO2 + H2O ; K2Cr2O7 + H2SO4 + 3SO2 + K2SO4 + H2O NO3– + H2SO4 4HNO3 HSO4– + HNO3 ; 2H2O + O2 + 4NO2 Cu + 4HNO3 5 Ag + HCl 4  H 2O  2 N O 2  [O] (C) 2H N O3  2 AgS, FeS, CuS or PbS + H2SO4 FeSO4 + H2S (A) CuSO4 + BaCl2 (B) 2NO2 + 2H2O + S (D) CuCl2 + BaSO4 (white) (E) CuSO4 + H2S CuS (black) + H2SO4 (F) 3CuS + 8HNO3 3Cu2+ + 6NO3– + 3S  + 2NO  + 4H2O Cu2+ + 4NH3 Cu2+ + [Fe(CN)6]4– [Cu(NH3)4]2+ (blue colour soluble (G) complex) Cu2[Fe(CN)6]  (chocolate brown) 27. (D) (A) NH3 + HCl NH4Cl (white fumes) (B) (NH4)2SO4 + 2NaOH (C) Nitrogen gas is obtained [Ag(NH3)2] Cl; Na2SO4 + 2NH3 + 2H2O Zn2+ + H2S AgCl  + 2NH4NO3 AgI  2NH3 + KCI ; [Ag(NH3)2Cl + KI Zn(NO3)2 + Cu (reddish brown) (C) AgCl  (white) + H+ [Ag(NH3)2] Cl + HNO3 0 26. (A) H2S + 2HNO3 Cu(NO3)2 + 2H2O + 2NO2 ; AgCl + 2NH4OH  H 2O  S  (B) H 2 S  [O]  Cu(NO3)2 + Zn Cr2(SO4)3 (green) ZnS  (white) + 2H+ 3Zn2+ + 2K+ + 2[Fe(CN)6]4 K2Zn3[Fe(CN)6]2  31. [A] = k+ and I– , [B] = Hg2+ and Cl– As black su;phide is only soluble in aquaregia and further it gives greyish black ppt with SnCl2 the one of the cation may be Hg2+. As salt mixture gives lilac colour in flame, the other cation is K+. 2KI + Cl2 KI + AgNO3 2KCl + I2 CCl4 (violet colour) AgI  (bright colour) + KNO3