Question

Identification of the negative ion in the unknown solution From your test results, what negative ion (anion) is present in your unknown? Explain your choice.

Answer 1

The ions are divided into cation and anion. Anions are generally detected by the sulphuric acid while cations are estimated by their group reagent. Preliminary test gives an idea to the presence of possible ions which can be confirmed by confirmatory test.
Lun Generaly cation and anion form salto come from the two source acid and base - Acid provide the negative ion and base provide possitive ion. - Some poriliminary test may give some idea about the presence of ions. Example ② Colour Inference - white colour asalts of Go, Ni, Fe, Co, Mn & Cy are absent - Dark green - Cr salt may present - light pink or Mg Magnese salts may present dirty white - light green :- Ferrous salt (1) Odour Inference - Smell of vinegar - Autate ion may present - smell of ammonia - Immonium salt. - Smell of rotten egy - Sulphide may present. ET) Action of heat = - Heat the sample in a test tube and examine the gas evolved. Observation Inference - CO2 colourless and Corbonate 8 turris lime water milky s Bocarbonate - Hs, Colourless gas, ni - Sulphide smell of rotten egg och vi turns head autate paper black - sa Pungent Oclour Sulphite and turns acidified ky (" thiosulphate paper green Ⓡ yellowish white bus

- Generally anions gives some reaction with dilute H, sou and Cone. H₂ Sou except sout 1704 and 30,97 - Cations are devicled an in six group and may be confirmed by group reagent Group Cation p Group reagent Tero Nhu, a Madh I Agt, Hght, phat he Hight IP67, 16: 4 Gt (dit this in presence of the S63t Ast Sn2 Al3+ Crest 3* NHull + NH GOH 22 Mat Co2+1,24 hs in presence of NH 4 , and NHGOH v Belt Cat Son Nhy Cl + MILLOH +(NMALC? v mat, kto Na HP OG + HHGOH H E Ans (2) Detection of Nach and Ca Cla - Nall and Calls, both are soluble in water, - Both give the test of chloride ion. Aquoces sol" + AgNO₃ sol" Age v (Maluf (alla) o n white ppt - How Nat ion can be tested by flame test Dip a platinum wire in conc. Hi and hold it in the blu bunsen flame until the plame no longer changes colour. Hot Next, dip the wire in se again, pick up some Nace poweler with wire and hold it on flame. A golden-yellow to

orange-yellow colour confirms the presence of Mod in. - How for Catt ion- Catt + Ammonium Calsium oxalitet oxalate (white precipit-ibi) - Calsium oxalati olso impart brick red colour to - the flame. + Wo Taip water reacts with KSCN and give diepired Colour indicate the presence of test (furric) ion. Fest + KS CAU + MgO -> [Fe (SCH) (HLC)s]** deep - red colour Aus 4 Test for Nhut ion - Heat 0.19 + 2me of 10%. NaOH => Smell of ammonía - Nhu + NaOH ANH + 40 + Hat and a glass rod dipped in conc. Hul brought to the mouth of test tube gives dence white fume - NH3 + Hee NHACH 1 white fume Test for pollon- (NH4)₂ PO. 12MoOo POS + HNO3 + (NH4)2MoOq Ammonium phospho- molibdate (yellow ppt.) - @ ci, Br, I doo not of silver does not dissolve in HNO3 © CO32- give Co, gas on reaction with - HU

. (C) Se ion give bright yellow flame (d) sou con give white Basoy precipitate with Bully which is not soluble in HNO₃