lab report qualitative analysis for identification of metal ions

1680 WordsOct 13, 20137 Pages
OBJECTIVE The main objective of this experiment is to carry out qualitative analysis to identify metal cations in unknown solution 1. INTRODUCTION An unknown material can be determined by using simple chemical tests and separations which is called as inorganic qualitative analysis. The separation of cations depends on the difference in their propensity to form precipitates. Separation scheme is used to classify cation into five groups on the basis of their physical and chemical behavior opposed to some reagents. Classification is based on whether there is formation of precipitates or not when metal cations react with the reagent. The five groups of cations and the characteristics of these groups are as follows: i. Group I Ag+, Hg+,…show more content…
3. A few drops of 6 M acetic acid were added until it became basic. 4. 6 drops of 1 M K2CrO4 was added to the solution and stirred. 5. The solution was centrifuged as ppt. was formed. 6. The supernatant was save for Procedure D(ii). Procedure D(ii) 1. 10 drops of 1 M K2CrO4 was added to the solution and stirred for about 10 minutes. 2. The solution was centrifuged as ppt. of oxalate was formed. RESULTS / OBSERVATION 1. On adding HCl to the initial sample Observation Balanced chemical equation Unknown: White precipitate was formed. Ag+ + Cl-  AgCl Hg2+ + Cl-  HgCl2 Pb2+ + Cl-  PbCl2 2. On adding H2S under acidic condition Observation Balanced chemical equation Unknown: Black precipitate was formed. 2Bi3+ + 3H2S  Bi2S3 + 6H+ Cu2+ + H2S  CuS + 2H+ Hg2+ + H2S  HgS + 2H+ 3. On adding H2S under acidic condition Observation Balanced chemical equation Unknown: Black precipitate was formed. Ni2+ + H2S  NiS + 2H+ Co3+ + 3H2S  Co2S3 + 6H+ Fe2+ H2S  FeS + 2H+ 4. On adding CO32- Observation Balanced chemical equation Unknown: Yellow precipitate was formed. Ba2+ + Cr042-  BaCrO4 Ca2+ + Cr042-  CaCrO4 Mg2+ + Cr042-  MgCrO4 Sr2+ + Cr042-  SrCrO4 5. On adding Cr042- Observation Balanced chemical equation Unknown: Yellow precipitate was formed. Ba2+ + Cr042-  BaCrO4 6. On adding C2O42- Observation Balanced chemical equation Unknown: Dark orange solution

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