Group IIA + III Cations PDF

Cations (group IIA and group III) Presented by: Bassma Hossam Anwar Assistant Lecturer in Pharmaceutical Analytical Chemistry department Cation is a positive charge ion + 𝐗  Cations are classified according to the precipitating reagent...

Cations (group IIA and group III) Presented by: Bassma Hossam Anwar Assistant Lecturer in Pharmaceutical Analytical Chemistry department Cation is a positive charge ion + 𝐗  Cations are classified according to the precipitating reagent into six groups: Group No. members Pptn reagent Ppt as Group II A 𝐇𝐠 +𝟐 , 𝐂𝐮+𝟐, 𝐂𝐝+𝟐 , 𝐁𝐢+𝟑 0.25N HCl + H2S HgS, CuS, CdS, 𝐁𝐢𝟐 𝐒𝟑 NH4OH + Al(𝐎𝐇)𝟑 , Fe(𝐎𝐇)𝟑 Group III 𝐀𝐥+𝟑 ,𝐅𝐞+𝟑 , 𝐂𝐫 +𝟑 10 % NH4Cl Cr(𝐎𝐇)𝟑 NH4OH + Group IV 𝐍𝐢+𝟐 , 𝐂𝐨+𝟐 , 𝐙𝐧+𝟐 NiS, CoS, ZnS 10 % NH4Cl + H2S NH4OH + Group V 𝐁𝐚+𝟐 , 𝐂𝐚+𝟐 , 𝐒𝐫 +𝟐 10 % NH4Cl + Ba𝐂𝐎𝟑 , Sr𝐂𝐎𝟑 , Ca𝐂𝐎𝟑 (NH4)2CO3 Group VI 𝐍𝐇𝟒 + , 𝐌𝐠 +𝟐 No specific reagent No specific ppt Centrifuge machine Centrifuge machine Centrifugation Group IIA Cations +𝟐 (𝐂𝐮 , +𝟐 𝐇𝐠 , +𝟐 𝐂𝐝 , +𝟑 𝐁𝐢 )  Group IIA Cations: +𝟐 +𝟐 +𝟐 +𝟑 (𝐂𝐮 , 𝐇𝐠 , 𝐂𝐝 , 𝐁𝐢 ) The precipitating reagent is 0.25N HCl + H2S  Scheme for identification of group II A cations (𝐂𝐮+𝟐 , 𝐇𝐠 +𝟐 , 𝐂𝐝+𝟐 , 𝐁𝐢+𝟑 ) 1) In a beaker → Powder + H2 O → If not dissolve, heart → If not dissolve, add c. HCl drop wise till dissolve 2) Add Xss H2 S 3) ppt If Canary yellow ppt→ Cd+2 If Brown ppt → Bi+3 If Black ppt → Hg +2 , Cu+2 (CdS) canary yellow ppt (𝐁𝐢𝟐 𝐒𝟑 ) Brown ppt (HgS, CuS) Black ppt  3) Ppt 4) Add 2ml dil. 𝐇𝐍𝐎𝟑 + 1ml dil. 𝐇𝟐 𝐒𝐎𝟒 , then Heat +𝟐 4b) If soluble 4a) If ppt (𝐇𝐠 ) (𝐂𝐮+𝟐 , 𝐂𝐝+𝟐 , 𝐁𝐢+𝟑 ) 𝑩𝒐𝒊𝒍 𝒕𝒊𝒍𝒍 𝒏𝒐 𝑶𝟐 𝒃𝒖𝒃𝒃𝒍𝒆𝒔. + 1ml c.HCl + 2dps 𝐇𝟐 𝐎𝟐 the ppt will be dissolved, then + Sn𝐂𝐥𝟐 → white to gray to black ppt (So we have 𝐇𝐠 +𝟐 )  4b) If soluble (𝐂𝐮+𝟐 , 𝐂𝐝+𝟐 , 𝐁𝐢+𝟑 ) 5) Cool → + c.𝐍𝐇𝟑 → shake 5a) If white ppt 5b) If soluble (𝐁𝐢+𝟑 ) (𝐂𝐮+𝟐 , 𝐂𝐝+𝟐 ) + 1ml alkali stannite (in a test tube 𝐒𝐧𝐂𝐥𝟐 + 𝟏𝟎% 𝑵𝒂𝑶𝑯 drop wise till ppt then re-dissolved) → blackening of ppt. (So we have 𝐁𝐢+𝟑 )  5b) If soluble 𝐂𝐮+𝟐 “blue solution” or 𝐂𝐝+𝟐 6) Divide into 2 test tubes 6a) Test for 𝐂𝐝 +𝟐 6b) Test for 𝐂𝒖+𝟐 solution + acetic acid + Solution + 𝐇𝟐 𝐒 1 dp K-ferrocyanide ↓ ↓ Canary yellow ppt Reddish brown ppt So we have 𝐂𝐝+𝟐 So we have 𝐂𝒖+𝟐 Group III Cations +𝟑 (𝐅𝐞 , +𝟑 𝐂𝐫 , +𝟑 𝐀𝐥 )  Group III Cations: +𝟑 +𝟑 +𝟑 (𝐅𝐞 , 𝐂𝐫 , 𝐀𝐥 ) The precipitating reagent is 𝐍𝐇𝟒 𝐎𝐇 𝐍𝐇𝟑 + 𝟏𝟎% 𝐍𝐇𝟒 𝐂𝐥  Scheme for identification of a mixture of group III cations (𝐅𝐞+𝟑 , 𝐂𝐫 +𝟑 , 𝐀𝐥+𝟑 ) 1) In a beaker → Powder + 𝐇𝟐 𝐎 → If not dissolve, heat → If not dissolve, add c. HCL drop wise with heating 2) Cool, then add 10% 𝐍𝐇𝟒 𝐂𝐥 + c.𝐍𝐇𝟑 till alkalinity Results: ppt of mix. of gp III (𝐀𝐥+𝟑 , 𝐅𝐞+𝟑 , 𝐂𝐫 +𝟑 ) White gelatinous reddish brown gray ppt → ppt →Al(𝐎𝐇)𝟑 , ppt →Fe(𝐎𝐇)𝟑 Cr(𝐎𝐇)𝟑  White gray ppt of gelatinous ppt Reddish brown Of Al(𝐎𝐇)𝟑 ppt of Fe(𝐎𝐇)𝟑 Cr(𝐎𝐇)𝟑  3) Add NaOH + dps 𝐇𝟐 𝐎𝟐 → boil till no 𝐎𝟐 bubbles, then centrifuge “This will dissolve the ppt of Al(OH)3 and Cr (OH)3 , While ppt of Fe(OH)3 will not be dissolved” solution ppt (𝐅𝐞+𝟑 ) (𝐀𝐥+𝟑 , 𝐂𝐫 +𝟑 ) + dil.𝐇𝐍𝐎𝟑 + 2dps H2O2, boil till dissolved and no O2 bubbles, then cool, then divide into 2 test tubes → do test for 𝐅𝐞+𝟑 1) Solution + 𝐍𝐇𝟒 𝐒𝐂𝐍 pd → 2) Solution + 1dp Blood red color K-ferrocyanide → blue ppt  4) solution (𝐀𝐥+𝟑 , 𝐂𝐫 +𝟑 ) Divide into 2 test tubes 1) test for 𝐀𝐥+𝟑 2) Test for 𝐂𝐫 +𝟑 Solution + 𝐍𝐇𝟒 𝐂𝐥 pd → boil Solution + dil. Acetic acid till for (1-2) mins, then cool acidity + 1dp pb-acetate ↓ ↓ white gelatinous ppt Yellow ppt