JK-TK/Newdata huggingface dataset:
(ii)An acid salt is formed when part/portion the ionizable /replaceable hydrogen in an acid is replaced by a metal or metallic /ammonium radical. Table showing normal and acid salts derived from common acids Acid name Chemical formula Basicity Normal salt Acid salt Hydrochloric acid HCl Monobasic Chloride(Cl-) None Nitric(V)acid HNO3 Monobasic Nitrate(V)(NO3-) None Nitric(III)acid HNO2 Monobasic Nitrate(III)(NO2-) None Sulphuric(VI)acid H2SO4 Dibasic Sulphate(VI) (SO42-) Hydrogen sulphate(VI) (HSO4-) Sulphuric(IV)acid H2SO3 Dibasic Sulphate(IV) (SO32-) Hydrogen sulphate(IV) (HSO3-) Carbonic(IV)acid H2CO3 Dibasic Carbonate(IV)(CO32-) Hydrogen carbonate(IV) (HCO3-) Phosphoric(V) H3PO4 Tribasic Phosphate(V)(PO43-) Dihydrogen
acid phosphate(V) (H2PO42-) Hydrogen diphosphate(V) (HP2O42-) The table below show shows some examples of salts. Base/alkali Cation Acid Anion Salt Chemical name of salts NaOH Na+ HCl Cl NaCl Sodium(I)chloride Mg(OH)2 Mg2+ H2SO4 SO42 MgSO4 Mg(HSO4)2 Magnesium sulphate(VI) Magnesium hydrogen sulphate(VI) Pb(OH)2 Pb2+ HNO3 NO3 Pb(NO3)2 Lead(II)nitrate(V) Ba(OH)2 Ba2+ HNO3 NO3 Ba(NO3)2 Barium(II)nitrate(V) Ca(OH)2 Ba2+ H2SO4 SO42 MgSO4 Calcium sulphate(VI) NH4OH NH4+ H3PO4 PO43 (NH4 )3PO4 (NH4 )2HPO4 NH4 H2PO4 Ammonium phosphate(V) Diammonium phosphate(V) Ammonium diphosphate(V) KOH K+ H3PO4 PO43 K3PO4 Potassium phosphate(V) Al(OH)3 Al3+ H2SO4 SO42 Al2(SO4)2 Aluminium(III)sulphate(VI) Fe(OH)2 Fe2+ H2SO4 SO42 FeSO4 Iron(II)sulphate(VI) Fe(OH)3 Fe3+ H2SO4 SO42 Fe2(SO4)2 Iron(III)sulphate(VI) (d) Some salts undergo hygroscopy, deliquescence and efflorescence. (i) Hygroscopic salts /compounds are those that absorb water from the atmosphere but do not form a solution.
Table showing normal and acid salts derived from common acids Acid name Chemical formula Basicity Normal salt Acid salt Hydrochloric acid HCl Monobasic Chloride(Cl-) None Nitric(V)acid HNO3 Monobasic Nitrate(V)(NO3-) None Nitric(III)acid HNO2 Monobasic Nitrate(III)(NO2-) None Sulphuric(VI)acid H2SO4 Dibasic Sulphate(VI) (SO42-) Hydrogen sulphate(VI) (HSO4-) Sulphuric(IV)acid H2SO3 Dibasic Sulphate(IV) (SO32-) Hydrogen sulphate(IV) (HSO3-) Carbonic(IV)acid H2CO3 Dibasic Carbonate(IV)(CO32-) Hydrogen carbonate(IV) (HCO3-) Phosphoric(V) H3PO4 Tribasic Phosphate(V)(PO43-) Dihydrogen
acid phosphate(V) (H2PO42-) Hydrogen diphosphate(V) (HP2O42-) The table below show shows some examples of salts. Base/alkali Cation Acid Anion Salt Chemical name of salts NaOH Na+ HCl Cl NaCl Sodium(I)chloride Mg(OH)2 Mg2+ H2SO4 SO42 MgSO4 Mg(HSO4)2 Magnesium sulphate(VI) Magnesium hydrogen sulphate(VI) Pb(OH)2 Pb2+ HNO3 NO3 Pb(NO3)2 Lead(II)nitrate(V) Ba(OH)2 Ba2+ HNO3 NO3 Ba(NO3)2 Barium(II)nitrate(V) Ca(OH)2 Ba2+ H2SO4 SO42 MgSO4 Calcium sulphate(VI) NH4OH NH4+ H3PO4 PO43 (NH4 )3PO4 (NH4 )2HPO4 NH4 H2PO4 Ammonium phosphate(V) Diammonium phosphate(V) Ammonium diphosphate(V) KOH K+ H3PO4 PO43 K3PO4 Potassium phosphate(V) Al(OH)3 Al3+ H2SO4 SO42 Al2(SO4)2 Aluminium(III)sulphate(VI) Fe(OH)2 Fe2+ H2SO4 SO42 FeSO4 Iron(II)sulphate(VI) Fe(OH)3 Fe3+ H2SO4 SO42 Fe2(SO4)2 Iron(III)sulphate(VI) (d) Some salts undergo hygroscopy, deliquescence and efflorescence. (i) Hygroscopic salts /compounds are those that absorb water from the atmosphere but do not form a solution. Some salts which are hygroscopic include anhydrous copper(II)sulphate(VI), anhydrous cobalt(II)chloride, potassium nitrate(V) common table salt.
e.g. CuCO3 (s) -> CuO(s) + CO2(g) CaCO3 (s) -> CaO(s) + CO2(g) PbCO3 (s) -> PbO(s) + CO2(g) FeCO3 (s) -> FeO(s) + CO2(g) ZnCO3 (s) -> ZnO(s) + CO2(g) (iii)Sodium hydrogen carbonate(IV) and Potassium hydrogen carbonate(IV)decompose on heating to give the corresponding carbonate (IV) and form water and carbon(IV)oxide gas. i.e. 2NaHCO 3(s) -> Na2CO3(s) + CO2(g) + H2O(l) 2KHCO 3(s) -> K2CO3(s) + CO2(g) + H2O(l) (iii) Calcium hydrogen carbonate (IV) and Magnesium hydrogen carbonate(IV) decompose on heating to give the corresponding carbonate (IV) and form water and carbon(IV)oxide gas. i. e. Ca(HCO3) 2(aq) -> CaCO3(s) + CO2(g) + H2O(l) Mg(HCO3) 2(aq) -> MgCO3(s) + CO2(g) + H2O(l) 15. Salts contain cation(positively charged ion) and anions(negatively charged ion).When dissolved in polar solvents/water. The cation and anion in a salt is determined/known usually by precipitation of the salt using a precipitating reagent. The colour of the precipitate is a basis of qualitative analysis of a compound. 16.Qualitative analysis is the process of identifying an unknown compound /salt by identifying the unique qualities of the salt/compound. It involves some of the following processes. (a)Reaction of cation with sodium/potassium hydroxide solution. Both sodium/potassium hydroxide solutions are precipitating reagents. The alkalis produce unique colour of a precipitate/suspension when a few/three drops is added and then excess alkali is added to unknown salt/compound solution. NB: Potassium hydroxide is not commonly used because it is more expensive than sodium hydroxide.
Both sodium/potassium hydroxide solutions are precipitating reagents. The alkalis produce unique colour of a precipitate/suspension when a few/three drops is added and then excess alkali is added to unknown salt/compound solution. NB: Potassium hydroxide is not commonly used because it is more expensive than sodium hydroxide. The table below shows the observations, inferences / deductions and explanations from the following test tube experiments: Procedure Put about 2cm3 of MgCl2, CaCl2, AlCl3, NaCl, KCl, FeSO4, Fe2(SO4) 3, CuSO4, ZnSO4NH4NO3, Pb(NO3) 2, Ba(NO3) 2 each into separate test tubes. Add three
drops of 2M sodium hydroxide solution then excess (2/3 the length of a standard test tube). Observation Inference Explanation No white precipitate Na+ and K+ Both Na+ and K+ ions react with OH- from 2M sodium hydroxide solution to form soluble colourless solutions Na+(aq) + OH-(aq) -> NaOH(aq) K+(aq) + OH-(aq) -> KOH(aq) No white precipitate then pungent smell of ammonia /urine NH4+ ions NH4+ ions react with 2M sodium hydroxide solution to produce pungent smelling ammonia gas NH4+ (aq) + OH-(aq) -> NH3 (g) + H2O(l) White precipitate insoluble in excess Ba2+ ,Ca2+, Mg2+ ions Ba2+ ,Ca2+ and Mg2+ ions react with OH- from 2M sodium hydroxide solution to form insoluble white precipitate of their hydroxides. Ba2+(aq) + 2OH-(aq) -> Ba(OH) 2(s) Ca2+(aq) + 2OH-(aq) -> Ca(OH) 2(s) Mg2+(aq) + 2OH-(aq) -> Mg(OH) 2(s) White precipitate soluble in excess Zn2+ ,Pb2+, Al3+ ions Pb2+ ,Zn2+ and Al3+ ions react with OH- from 2M sodium hydroxide solution to form insoluble white precipitate of their hydroxides.
Add three
drops of 2M sodium hydroxide solution then excess (2/3 the length of a standard test tube). Observation Inference Explanation No white precipitate Na+ and K+ Both Na+ and K+ ions react with OH- from 2M sodium hydroxide solution to form soluble colourless solutions Na+(aq) + OH-(aq) -> NaOH(aq) K+(aq) + OH-(aq) -> KOH(aq) No white precipitate then pungent smell of ammonia /urine NH4+ ions NH4+ ions react with 2M sodium hydroxide solution to produce pungent smelling ammonia gas NH4+ (aq) + OH-(aq) -> NH3 (g) + H2O(l) White precipitate insoluble in excess Ba2+ ,Ca2+, Mg2+ ions Ba2+ ,Ca2+ and Mg2+ ions react with OH- from 2M sodium hydroxide solution to form insoluble white precipitate of their hydroxides. Ba2+(aq) + 2OH-(aq) -> Ba(OH) 2(s) Ca2+(aq) + 2OH-(aq) -> Ca(OH) 2(s) Mg2+(aq) + 2OH-(aq) -> Mg(OH) 2(s) White precipitate soluble in excess Zn2+ ,Pb2+, Al3+ ions Pb2+ ,Zn2+ and Al3+ ions react with OH- from 2M sodium hydroxide solution to form insoluble white precipitate of their hydroxides. Zn2+(aq) + 2OH-(aq) -> Zn(OH) 2(s) Pb2+(aq) + 2OH-(aq) -> Pb(OH) 2(s) Al3+(aq) + 3OH-(aq) -> Al(OH) 3(s)
The hydroxides formed react with more OH- ions to form complex salts/ions.
Observation Inference Explanation No white precipitate Na+ and K+ Both Na+ and K+ ions react with OH- from 2M sodium hydroxide solution to form soluble colourless solutions Na+(aq) + OH-(aq) -> NaOH(aq) K+(aq) + OH-(aq) -> KOH(aq) No white precipitate then pungent smell of ammonia /urine NH4+ ions NH4+ ions react with 2M sodium hydroxide solution to produce pungent smelling ammonia gas NH4+ (aq) + OH-(aq) -> NH3 (g) + H2O(l) White precipitate insoluble in excess Ba2+ ,Ca2+, Mg2+ ions Ba2+ ,Ca2+ and Mg2+ ions react with OH- from 2M sodium hydroxide solution to form insoluble white precipitate of their hydroxides. Ba2+(aq) + 2OH-(aq) -> Ba(OH) 2(s) Ca2+(aq) + 2OH-(aq) -> Ca(OH) 2(s) Mg2+(aq) + 2OH-(aq) -> Mg(OH) 2(s) White precipitate soluble in excess Zn2+ ,Pb2+, Al3+ ions Pb2+ ,Zn2+ and Al3+ ions react with OH- from 2M sodium hydroxide solution to form insoluble white precipitate of their hydroxides. Zn2+(aq) + 2OH-(aq) -> Zn(OH) 2(s) Pb2+(aq) + 2OH-(aq) -> Pb(OH) 2(s) Al3+(aq) + 3OH-(aq) -> Al(OH) 3(s)
The hydroxides formed react with more OH- ions to form complex salts/ions. Zn(OH) 2(s) + 2OH(aq) -> [ Zn(OH) 4]2-(aq) Pb(OH) 2(s) + 2OH(aq) -> [ Pb(OH) 4]2-(aq) Al(OH) 3(s) + OH(aq) -> [ Al(OH) 4]-(aq) Blue precipitate insoluble in excess Cu2+ Cu2+ ions react with OH- from 2M sodium hydroxide solution to form insoluble blue precipitate of copper(II) hydroxide.
Ba2+(aq) + 2OH-(aq) -> Ba(OH) 2(s) Ca2+(aq) + 2OH-(aq) -> Ca(OH) 2(s) Mg2+(aq) + 2OH-(aq) -> Mg(OH) 2(s) White precipitate soluble in excess Zn2+ ,Pb2+, Al3+ ions Pb2+ ,Zn2+ and Al3+ ions react with OH- from 2M sodium hydroxide solution to form insoluble white precipitate of their hydroxides. Zn2+(aq) + 2OH-(aq) -> Zn(OH) 2(s) Pb2+(aq) + 2OH-(aq) -> Pb(OH) 2(s) Al3+(aq) + 3OH-(aq) -> Al(OH) 3(s)
The hydroxides formed react with more OH- ions to form complex salts/ions. Zn(OH) 2(s) + 2OH(aq) -> [ Zn(OH) 4]2-(aq) Pb(OH) 2(s) + 2OH(aq) -> [ Pb(OH) 4]2-(aq) Al(OH) 3(s) + OH(aq) -> [ Al(OH) 4]-(aq) Blue precipitate insoluble in excess Cu2+ Cu2+ ions react with OH- from 2M sodium hydroxide solution to form insoluble blue precipitate of copper(II) hydroxide. Cu2+(aq) + 2OH-(aq) -> Cu(OH) 2(s) Green precipitate insoluble in excess On adding 3cm3 of hydrogen peroxide, brown/yellow solution formed Fe2+ Fe2+ oxidized to Fe3+ Fe2+ ions react with OH- from 2M sodium hydroxide solution to form insoluble green precipitate of Iron(II) hydroxide.
Zn2+(aq) + 2OH-(aq) -> Zn(OH) 2(s) Pb2+(aq) + 2OH-(aq) -> Pb(OH) 2(s) Al3+(aq) + 3OH-(aq) -> Al(OH) 3(s)
The hydroxides formed react with more OH- ions to form complex salts/ions. Zn(OH) 2(s) + 2OH(aq) -> [ Zn(OH) 4]2-(aq) Pb(OH) 2(s) + 2OH(aq) -> [ Pb(OH) 4]2-(aq) Al(OH) 3(s) + OH(aq) -> [ Al(OH) 4]-(aq) Blue precipitate insoluble in excess Cu2+ Cu2+ ions react with OH- from 2M sodium hydroxide solution to form insoluble blue precipitate of copper(II) hydroxide. Cu2+(aq) + 2OH-(aq) -> Cu(OH) 2(s) Green precipitate insoluble in excess On adding 3cm3 of hydrogen peroxide, brown/yellow solution formed Fe2+ Fe2+ oxidized to Fe3+ Fe2+ ions react with OH- from 2M sodium hydroxide solution to form insoluble green precipitate of Iron(II) hydroxide. Fe2+(aq) + 2OH-(aq) -> Fe(OH) 2(s) Hydrogen peroxide is an oxidizing agent that oxidizes green Fe2+ oxidized to brown Fe3+ Fe(OH) 2(s) + 2H+ -> Fe(OH) 3(aq) Brown precipitate insoluble in excess Fe3+ Fe3+ ions react with OH- from 2M sodium hydroxide solution to form insoluble brown precipitate of Iron(II) hydroxide. Fe3+(aq) + 3OH-(aq) -> Fe(OH) 3(s) (b)Reaction of cation with aqueous ammonia Aqueous ammonia precipitating reagent that can be used to identify the cations present in a salt. Like NaOH/KOH the OH- ion in NH4OH react with the cation to form a characteristic hydroxide .
Fe2+(aq) + 2OH-(aq) -> Fe(OH) 2(s) Hydrogen peroxide is an oxidizing agent that oxidizes green Fe2+ oxidized to brown Fe3+ Fe(OH) 2(s) + 2H+ -> Fe(OH) 3(aq) Brown precipitate insoluble in excess Fe3+ Fe3+ ions react with OH- from 2M sodium hydroxide solution to form insoluble brown precipitate of Iron(II) hydroxide. Fe3+(aq) + 3OH-(aq) -> Fe(OH) 3(s) (b)Reaction of cation with aqueous ammonia Aqueous ammonia precipitating reagent that can be used to identify the cations present in a salt. Like NaOH/KOH the OH- ion in NH4OH react with the cation to form a characteristic hydroxide . Below are the observations ,inferences and explanations of the reactions of aqueous ammonia with salts from the following test tube reactions. Procedure Put about 2cm3 of MgCl2, CaCl2, AlCl3, NaCl, KCl, FeSO4, Fe2(SO4) 3, CuSO4, ZnSO4NH4NO3, Pb(NO3) 2, Ba(NO3) 2 each into separate test tubes. Add three drops of 2M aqueous ammonia then excess (2/3 the length of a standard test tube). Observation Inference Explanation No white precipitate Na+ and K+ NH4+,Na+ and K+ ions react with OH- from 2M aqueous ammonia to form soluble colourless solutions NH4+ (aq) + OH-(aq) -> NH4+OH(aq) Na+(aq) + OH-(aq) -> NaOH(aq) K+(aq) + OH-(aq) -> KOH(aq) White precipitate insoluble in excess Ba2+ ,Ca2+, Mg2+ ,Pb2+, Al3+, ions Ba2+ ,Ca2+,Mg2+ ,Pb2+ and Al3+, ions react with OH- from 2M aqueous ammonia to form insoluble white precipitate of their hydroxides.
Procedure Put about 2cm3 of MgCl2, CaCl2, AlCl3, NaCl, KCl, FeSO4, Fe2(SO4) 3, CuSO4, ZnSO4NH4NO3, Pb(NO3) 2, Ba(NO3) 2 each into separate test tubes. Add three drops of 2M aqueous ammonia then excess (2/3 the length of a standard test tube). Observation Inference Explanation No white precipitate Na+ and K+ NH4+,Na+ and K+ ions react with OH- from 2M aqueous ammonia to form soluble colourless solutions NH4+ (aq) + OH-(aq) -> NH4+OH(aq) Na+(aq) + OH-(aq) -> NaOH(aq) K+(aq) + OH-(aq) -> KOH(aq) White precipitate insoluble in excess Ba2+ ,Ca2+, Mg2+ ,Pb2+, Al3+, ions Ba2+ ,Ca2+,Mg2+ ,Pb2+ and Al3+, ions react with OH- from 2M aqueous ammonia to form insoluble white precipitate of their hydroxides. Pb2+ (aq) + 2OH-(aq) -> Pb(OH) 2(s) Al3+ (aq) + 3OH-(aq) -> Al(OH) 3(s) Ba2+ (aq) + 2OH-(aq) -> Ba(OH) 2(s) Ca2+ (aq) + 2OH-(aq) -> Ca(OH) 2(s) Mg2+ (aq) + 2OH-(aq) -> Mg(OH) 2(s) White precipitate soluble in excess Zn2+ ions Zn2+ ions react with OH- from 2M aqueous ammonia to form insoluble white precipitate of Zinc hydroxide. Zn2+(aq) + 2OH-(aq) -> Zn(OH) 2(s) The Zinc hydroxides formed react NH3(aq) to form a complex salts/ions.
Observation Inference Explanation No white precipitate Na+ and K+ NH4+,Na+ and K+ ions react with OH- from 2M aqueous ammonia to form soluble colourless solutions NH4+ (aq) + OH-(aq) -> NH4+OH(aq) Na+(aq) + OH-(aq) -> NaOH(aq) K+(aq) + OH-(aq) -> KOH(aq) White precipitate insoluble in excess Ba2+ ,Ca2+, Mg2+ ,Pb2+, Al3+, ions Ba2+ ,Ca2+,Mg2+ ,Pb2+ and Al3+, ions react with OH- from 2M aqueous ammonia to form insoluble white precipitate of their hydroxides. Pb2+ (aq) + 2OH-(aq) -> Pb(OH) 2(s) Al3+ (aq) + 3OH-(aq) -> Al(OH) 3(s) Ba2+ (aq) + 2OH-(aq) -> Ba(OH) 2(s) Ca2+ (aq) + 2OH-(aq) -> Ca(OH) 2(s) Mg2+ (aq) + 2OH-(aq) -> Mg(OH) 2(s) White precipitate soluble in excess Zn2+ ions Zn2+ ions react with OH- from 2M aqueous ammonia to form insoluble white precipitate of Zinc hydroxide. Zn2+(aq) + 2OH-(aq) -> Zn(OH) 2(s) The Zinc hydroxides formed react NH3(aq) to form a complex salts/ions. Zn(OH) 2(s) + 4NH3(aq) ->[ Zn(NH3) 4]2+(aq)+ 2OH-(aq) Blue precipitate Cu2+ Cu2+ ions react with OH- from 2M aqueous
that dissolves in excess ammonia solution to form a deep/royal blue solution ammonia to form blue precipitate of copper(II) hydroxide. Cu2+(aq) + 2OH-(aq) -> Cu(OH) 2(s) The copper(II) hydroxide formed react NH3(aq) to form a complex salts/ions.
Zn2+(aq) + 2OH-(aq) -> Zn(OH) 2(s) The Zinc hydroxides formed react NH3(aq) to form a complex salts/ions. Zn(OH) 2(s) + 4NH3(aq) ->[ Zn(NH3) 4]2+(aq)+ 2OH-(aq) Blue precipitate Cu2+ Cu2+ ions react with OH- from 2M aqueous
that dissolves in excess ammonia solution to form a deep/royal blue solution ammonia to form blue precipitate of copper(II) hydroxide. Cu2+(aq) + 2OH-(aq) -> Cu(OH) 2(s) The copper(II) hydroxide formed react NH3(aq) to form a complex salts/ions. Cu(OH) 2 (s) + 4NH3(aq) ->[ Cu(NH3) 4]2+(aq)+ 2OH-(aq) Green precipitate insoluble in excess. On adding 3cm3 of hydrogen peroxide, brown/yellow solution formed Fe2+ Fe2+ oxidized to Fe3+ Fe2+ ions react with OH- from 2M aqueous ammonia to form insoluble green precipitate of Iron(II) hydroxide. Fe2+(aq) + 2OH-(aq) -> Fe(OH) 2(s) Hydrogen peroxide is an oxidizing agent that oxidizes green Fe2+ oxidized to brown Fe3+ Fe(OH) 2(s) + 2H+ -> Fe(OH) 3(aq) Brown precipitate insoluble in excess Fe3+ Fe3+ ions react with OH- from 2M aqueous ammonia to form insoluble brown precipitate of Iron(II) hydroxide. Fe3+(aq) + 3OH-(aq) -> Fe(OH) 3(s) Note (i) Only Zn2+ ions/salts form a white precipitate that dissolve in excess of both 2M sodium hydroxide and 2M aqueous ammonia. (ii) Pb2+ and Al3+ ions/salts form a white precipitate that dissolve in excess of 2M sodium hydroxide but not in 2M aqueous ammonia.
Fe2+(aq) + 2OH-(aq) -> Fe(OH) 2(s) Hydrogen peroxide is an oxidizing agent that oxidizes green Fe2+ oxidized to brown Fe3+ Fe(OH) 2(s) + 2H+ -> Fe(OH) 3(aq) Brown precipitate insoluble in excess Fe3+ Fe3+ ions react with OH- from 2M aqueous ammonia to form insoluble brown precipitate of Iron(II) hydroxide. Fe3+(aq) + 3OH-(aq) -> Fe(OH) 3(s) Note (i) Only Zn2+ ions/salts form a white precipitate that dissolve in excess of both 2M sodium hydroxide and 2M aqueous ammonia. (ii) Pb2+ and Al3+ ions/salts form a white precipitate that dissolve in excess of 2M sodium hydroxide but not in 2M aqueous ammonia. (iii) Cu2+ ions/salts form a blue precipitate that dissolve to form a deep/royal blue solution in excess of 2M aqueous ammonia but only blue insoluble precipitate in 2M sodium hydroxide (c)Reaction of cation with Chloride (Cl-)ions All chlorides are soluble in water except Silver chloride and Lead (II)chloride (That dissolve in hot water).When a soluble chloride like NaCl, KCl, NH4Cl is
added to about 2cm3 of a salt containing Ag+ or Pb2+ions a white precipitate of AgCl or PbCl2 is formed. The following test tube reactions illustrate the above. Experiment Put about 2cm3 of silver nitrate(V) andLead(II)nitrate(V)solution into separate test tubes. Add five drops of NaCl /KCl / NH4Cl/HCl. Heat to boil. Observation Inference Explanation (i)White precipitate does not dissolve on heating Ag+ ions Ag+ ions reacts with Cl- ions from a soluble chloride salt to form a white precipitate of AgCl (ii)White precipitate dissolve on heating Pb2+ ions Pb2+ ions reacts with Cl- ions from a soluble chloride salt to form a white precipitate of PbCl2. PbCl2 dissolves on heating. Note Both Pb2+ and Al3+ ions forms an insoluble white precipitate in excess aqueous ammonia.
Observation Inference Explanation (i)White precipitate does not dissolve on heating Ag+ ions Ag+ ions reacts with Cl- ions from a soluble chloride salt to form a white precipitate of AgCl (ii)White precipitate dissolve on heating Pb2+ ions Pb2+ ions reacts with Cl- ions from a soluble chloride salt to form a white precipitate of PbCl2. PbCl2 dissolves on heating. Note Both Pb2+ and Al3+ ions forms an insoluble white precipitate in excess aqueous ammonia. A white precipitate on adding Cl- ions/salts shows Pb2+. No white precipitate on adding Cl- ions/salts shows Al3+. Adding a chloride/ Cl- ions/salts can thus be used to separate the identity of Al3+ and Pb2+. (d)Reaction of cation with sulphate(VI)/SO42- and sulphate(IV)/SO32- ions All sulphate(VI) and sulphate(IV)/SO32- ions/salts are soluble/dissolve in water except Calcium sulphate(VI)/CaSO4, Calcium sulphate(IV)/CaSO3, Barium sulphate(VI)/BaSO4, Barium sulphate(IV)/BaSO3, Lead(II) sulphate(VI)/PbSO4 and Lead(II) sulphate(IV)/PbSO3.When a soluble sulphate(VI)/SO42- salt like Na2SO4, H2SO4, (NH4)2SO4 or Na2SO3 is added to a salt containing Ca2+, Pb2+, Ba2+ ions, a white precipitate is formed. The following test tube experiments illustrate the above. Procedure Place about 2cm3 of Ca(NO3)2, Ba(NO3)2, BaCl2 and Pb(NO3)2, in separate boiling tubes. Add six drops of sulphuric(VI)acid /sodium sulphate(VI)/ammonium sulphate(VI)solution. Repeat with six drops of sodium sulphate(IV). Observation Inference Explanation White Ca2+, Ba2+, CaSO3 and CaSO4 do not form a thick precipitate as
precipitate Pb2+ ions they are sparingly soluble.
Add six drops of sulphuric(VI)acid /sodium sulphate(VI)/ammonium sulphate(VI)solution. Repeat with six drops of sodium sulphate(IV). Observation Inference Explanation White Ca2+, Ba2+, CaSO3 and CaSO4 do not form a thick precipitate as
precipitate Pb2+ ions they are sparingly soluble. Ca2+(aq)+ SO32-(aq) -> CaSO3(s) Ca2+(aq)+ SO42-(aq) -> CaSO4(s) Ba2+(aq)+ SO32-(aq) -> BaSO3(s) Ba2+(aq)+ SO42-(aq) -> BaSO4(s) Pb2+(aq)+ SO32-(aq) -> PbSO3(s) Pb2+(aq)+ SO42-(aq) -> PbSO4(s) (e)Reaction of cation with carbonate(IV)/CO32- ions All carbonate salts are insoluble except sodium/potassium carbonate(IV) and ammonium carbonate(IV). They dissociate /ionize to release CO32- ions. CO32- ions produce a white precipitate when the soluble carbonate salts is added to any metallic cation. Procedure Place about 2cm3 of Ca(NO3)2, Ba(NO3)2, MgCl2 ,Pb(NO3)2 andZnSO4 in separate boiling tubes. Add six drops of Potassium /sodium carbonate(IV)/ ammonium carbonate (IV)solution. Observation Inference Explanation Green precipitate Cu2+ ,Fe2+,ions CO32-(aq) Copper(II)carbonate(IV) and Iron(II) carbonate (IV) are precipitated as insoluble green precipitates. Cu2+(aq)+ CO32-(aq) -> CuCO3(s) Fe2+(aq)+ CO32-(aq) -> FeCO3(s) When sodium carbonate(IV)is added to CuCO3(s) the CO32-(aq) ions are first hydrolysed to produce CO2(g) and OH(aq)ions. CO32-(aq) + H2O (l) -> CO2 (g) + 2OH- (aq) The OH-(aq) ions further react to form basic copper(II) carbonate(IV). Basic copper(II) carbonate(IV) is the only green salt of copper.
Cu2+(aq)+ CO32-(aq) -> CuCO3(s) Fe2+(aq)+ CO32-(aq) -> FeCO3(s) When sodium carbonate(IV)is added to CuCO3(s) the CO32-(aq) ions are first hydrolysed to produce CO2(g) and OH(aq)ions. CO32-(aq) + H2O (l) -> CO2 (g) + 2OH- (aq) The OH-(aq) ions further react to form basic copper(II) carbonate(IV). Basic copper(II) carbonate(IV) is the only green salt of copper. Cu2+(aq)+ CO32-(aq)+2OH- (aq)
->CuCO3.Cu(OH)2 (s) White precipitate CO32- White ppt of the carbonate(IV)salt is precipitated Ca2+(aq) + CO32- (aq) -> CaCO3(s) Mg2+(aq) + CO32- (aq) -> MgCO3(s) Pb2+(aq) + CO32- (aq) -> PbCO3(s) Zn2+(aq) + CO32- (aq) -> ZnCO3(s) Note (i)Iron(III)carbonate(IV) does not exist. (ii)Copper(II)Carbonate(IV) exist only as the basic CuCO3.Cu(OH) 2 (iii)Both BaCO3 and BaSO3 are insoluble white precipitate. If hydrochloric acid is added to the white precipitate; I. BaCO3 produces CO2 gas. When bubbled/directed into lime water solution,a white precipitate is formed. II. I. BaSO3 produces SO2 gas. When bubbled/directed into orange acidified potassium dichromate(VI) solution, it turns to green/decolorizes acidified potassium manganate(VII). (f) Reaction of cation with sulphide / S2- ions All sulphides are insoluble black solids/precipitates except sodium sulphide/ Na2S/ potassium sulphide/K2S.When a few/3drops of the soluble sulphide is added to a metal cation/salt, a black precipitate is formed. Procedure Place about 2cm3 of Cu(NO3)2, FeSO4, MgCl2,Pb(NO3)2 and ZnSO4 in separate boiling tubes.