nitric acid (dissolves) add 3–4 drops of silver pale cream precipitate nitrate solution forms AgBr(s) – bromide (Br–) (precipitate forms) precipitate is slightly soluble add 2–3 cm3 of in ammonia (partially 1 mol dm–3 ammonia dissolves) solution pale yellow precipitate forms AgI(s) – iodide (I–) precipitate is insoluble in ammonia solution (doesn’t dissolve) B test for sulfate ions – sulfate a white precipitate forms – add a few drops of (SO42–) BaSO4(s) dilute nitric acid add a few drops of barium nitrate solution C test for carbonate – ions carbonate bubbles of gas form CO2(g) – (CO32–) add 1 cm3 dilute nitric acid drop by drop down the inside of the tube Test D add 1 cm3 sodium hydroxide Test E add 1 cm3 ammonia – – solution drop-by-drop solution drop-by-drop Cation Observation Expected Observation Expected observation made () observation made () Blue gelatinous copper Blue gelatinous precipitate precipitate forms; (Cu2+) forms Cu(OH)2(s) dissolves in – excess NH3 iron(II) green gelatinous precipitate Green gelatinous (Fe2+) forms Fe(OH)2(s) precipitate forms – rust-brown gelatinous Rust-brown iron(III) precipitate forms gelatinous – (Fe3+) Fe(OH)3(s) precipitate forms white precipitate forms lead(II) white precipitate (Pb(OH)2(s)) dissolves in – (Pb2+) forms excess sodium hydroxide white precipitate white precipitate forms which – zinc (Zn2+) Zn(OH)2(s) dissolves in excess ammonia
nitric acid add 3–4 drops of silver nitrate solution (precipitate forms) add 2–3 cm3 of 1 mol dm–3 ammonia solution (dissolves) bromide (Br–) pale cream precipitate forms – AgBr(s) precipitate is slightly soluble in ammonia (partially dissolves) iodide (I–) pale yellow precipitate forms – AgI(s) precipitate is insoluble in ammonia solution (doesn’t dissolve) sulfate (SO42–) B – test for sulfate ions add a few drops of dilute nitric acid add a few drops of barium nitrate solution a white precipitate forms – BaSO4(s) carbonate (CO32–) C – test for carbonate ions add 1 cm3 dilute nitric acid drop by drop down the inside of the tube bubbles of gas form – CO2(g) Cation Test D – add 1 cm3 sodium hydroxide solution drop-by-drop Test E – add 1 cm3 ammonia solution drop-by-drop Expected observation Observation made () Expected observation Observation made () copper (Cu2+) Blue gelatinous precipitate forms – Cu(OH)2(s) Blue gelatinous precipitate forms; dissolves in excess NH3 iron(II) (Fe2+) green gelatinous precipitate forms – Fe(OH)2(s) Green gelatinous precipitate forms iron(III) (Fe3+) rust-brown gelatinous precipitate forms – Fe(OH)3(s) Rust-brown gelatinous precipitate forms lead(II) (Pb2+) white precipitate forms (Pb(OH)2(s)) – dissolves in excess sodium hydroxide white precipitate forms zinc (Zn2+) white precipitate – Zn(OH)2(s) white precipitate forms which dissolves in excess ammonia
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