Reactions of Group 0, 1 and 2 Cations

University:
High School
Course:
High School Chemistry
Academic year:

2023
Views:

173

Pages:

3
Author:

Yasin N.

REACTION OF ZERO GROUP CATION Reactions of Ammonium NH No precipitate. 1. Action with Na₂CO,. A little of Na₂CO, solution is added to an aqueous solution of ammonium salt. 2. To an aqueous solution of the salt, a little NaOH solution is added. 3. A glass rod dipped in conc. HCl is shown to the above gas. 4. To a little of the solution Nessler's reagent is added. Colourless gas with the smell of ammonia. Dense white fumes A brown precipitate is formed. Ammonium carbonate formed is soluble in water. 2NH CI+Na₂CO, →2NaCl + (NH4)2CO, (soluble) NaOH decomposes ammonium salt into ammonia. NHCl + NaOH NaCl + NH+H₂O This is due to the formation of ammonium chloride. NH,+HCl→NH CI The precipitate is due to the formation of mercuric amino iodide, NH,Hg, REACTION OF GROUP I CATION Reactions of Lead Pb 1. To a little of the salt solution dil. HCl is added. 2. To the salt solution potassium iodide solution is added. 3. To the salt solution acetic acid and potassium chromate solution are added. A white precipitate formed is soluble in hot water. Yellow precipitate soluble in hot water but reappears as golden spangles on cooling. Yellow precipitate. Lead chloride is precipitated. Pb(NO,), +2HCl PbCI, 4+2HNO, PbCl, is soluble is hot water. Lead iodide is precipitated. Pb(NO₂), +2KI2KNO, + Pbl Lead chromate is precipitated. Pb(NO₂), + K2CrO PbCrO, REACTION OF GROUP II CATIONS 1. To a little of the salt solution dil. HCI is added and then H.S gas is passed. 2. To a little of the salt solution NH OH is added drop by drop till in excess. 3. To a little of the salt solution acetic acid and potassium fer- rocyanide solution are added. 1. Reactions of Copper, Cu²+ A black precipitate. A pale blue precipitate soluble in excess of NH OH to give a deep blue solution. A chocolate brown precipi- tate is formed. Copper sulphide is precipitated. CuSO,+H₂SH₂SO₄ + CuS↓ The Cu(OH), precipitate is soluble in excess of NH Oн. CuSO+2NH OH → Cu(OH), ↓+(NH),SO Cu(OH), +4NH, [Cu(NH,),] (OH), This is due to the formation of copper ferrocyanide. 2CuSO,+[K [Fe(CN)]→ Cu, [Fe(CN)]+2K,SO, 1. Hydrogen sulphide is passed through a slightly acidic (dil. HCI) solution of cadmium salt. 2. To a little of the salt solution ammonium hydroxide is added drop by drop till in excess 2. Reactions of Cadmium, Cd2+ A yellow precipitate is formed. A white precipitate soluble in Cd(OH), + formed is soluble in excess of NH OH is formed. excess of NH OH. The yellow precipitate is cad- mium sulphide. 3. Hydrogen sulphide is passed through the above solution. 1. A little of the salt solution is acidified with dil. HCl and hy- drogen sulphide is passed through it. 2. The above precipitate sepa- rated, washed and then warmed with ammonium carbonate so- lution. 3. The above solution is acidified with dil. HCl A yellow precipitate is ob- tained 3. Reactions of Arsenic As³+ A yellow precipitate is formed. Precipitate dissolved. A yellow precipitate is formed. CdSO+2NH OH→Cd(OH) CdSO+(NH)₂SO₄+2NH OH →[Cd(NH),]SO,+2H₂O +(NH), SO, Cadmium sulphide is precipi- tated. Arsenic sulphide is precipitated 2AsCI, +3H2S → As,S,+6 HCl Ammonium arsenite formed is soluble. This is due to the formation of arsenic sulphide.