Experiment:
To analyze a sample of stainless steel (spoon).
Theory:
Stainless Steel is an alloy of 18% chromium and nickel which is resistant to corrosion, and is therefore, used for making utensils and surgical instrument, etc.
Apparatus:
China dish, Test tube, Funnel, And common Laboratory reagents.
Procedure:
1. Place a piece of stainless steel spoon in aquarezia for 1 day.
2. Prepare O.S. of this solution.
3. Use the O.S. prepared above for the testing of different elements present in it.
Observation Table:
Experiment Observation Inference
1. O.S.+Solid NH4Cl+NH4OH(in excess) PPT. formed III Group Present
2. Dissolve PPT. in HCl and filter it. Residual and filtrate is obtained
3. Divide the filtrate in two parts.
4. I part +K4[Fe(CN)]6 Dark Blue Colour Fe+3 Confirmed.
5. II Part +KCNS Red Colour Fe+3 Confirmed.
6. Residue+(KNO3+Na2CO3)(fusion Mixture)+Heat+cool+H2O+CH3COOH+ CH3COO)2Pb Yellow PPt. Cr+3 Confirmed.
7. O.S.+NH4OH+DMG Rosy Red PPt. Ni+2 Confirmed.
8. Borax Bead Test Brown coloured flames Ni+2 Confirmed.
Reactions:
Confirmatory Test for Iron:
Fe+2+2HCl+ [O] ? Fe+3 +H2O
1. Potassium Ferro cyanide Test:
FeCl3(aq) + K4Fe(CN)6 ? K4Fe[Fe(CN)6] +3KCl
Ferric Potassium Potassium Ferric
Chloride Ferrocyanide Ferrocyanide
(Prussian blue)
2. Potassium Thiocyanate Test:
Fe3+ (aq) + 6KCNS(aq) ? K3Fe(CNS)6 + K+
Ferric ion Potassium Hexathiosaulphate Potassium
(Salt solution) thiocyanate ferrate (III) ion ion
(Blood Red Colour)
Confirmatory Test for Nickel:
1. Dissolution of the Ni2+ in Aqua Regia:
Ni2+(s) + 2HCl + [O] ? NiCl2(aq) + H2O(l)
Nickel(II) From HNO3 Nickel(II)
ion Aqua Regia Chloride
2. Dimethyl Glyoxime Test: OH O
| ?
NiCl2 +2NH4OH + CH3-C=N-OH? CH3-C=N N=C- CH3
| | Ni
CH3-C=N-OH CH3-C=N N=C- CH3 Dimethyl Glyoxime ? |
O OH
(Rosy Red Precipitate)
+2NH4Cl(aq ) + 2H2O(l)
1. 2Cr(OH)3 +3KNO3+2Na2CO3 ? 2Na2CrO4+3KNO2+3H2O+3CO2
Chromium Sodium
Hydroxide Chromate
2. Na2CrO4 + (CH3COO)2Pb ? PbCrO4(ppt.)+2CH3COONa
(Yellow ppt.)
Result: Stainless steel has iron, chromium and nickel as its constituents.
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