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Chemistry Practical Help for xii

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Experiment

Observation

Preliminary Tests

Colour and appearance

Colourless

Blue, bluish green or green Pale green Pink Brown or yellow Solubility in water Soluble Insoluble Brisk effervescence

Brown fumes evolved Action of heat

Brown fumes with irritating smell

Flame test Blue or bluish green colour Brick red colour

Crimson

Water soluble and no precipitate with Na2CO3 solution

Water soluble and precipitate with Na2CO3 solution

Solubility in/action of dil. HCl

If insoluble in water the salt is treated with dil. HCl

Colourless gas with the smell of rotten eggs is evolvedwhich turned lead acetate paper black

Colourless, suffocating smelling gas which turned acidified

potassium dichromate paper green is evolved

Heat strongly a little of the salt in a dry test tube

Colourless, odourless gas turning lime water milky

Residue yellow when hot and white when cold

Pleasant smell of inflammable vapours are evolved

A colourless gas with smell of burnt sulphur evolved which turned acidified potassium dichromate paper green

Smell of burnt sulphur and yellow sublimate

Paste of salt and conc. HCl is introduced into Bunsen

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Light green colour Liliac (violet)

Analysis of Acid Radicals

Identification Tests Refer to row no. 10

Vinegar smell is obtained No characteristic reaction

Confirmatory Tests

A deep red colouration is obtained Chloride:

Sulphate:

Soln + lead acetate soln Paste of salt and conc. HCl

is introduced into Bunsen flame

Action of dil. HCl (about 1mL)

Action of dil. Sulphuric acid (watch glass)

Action of conc. Sulphuric acid (heating in a dry test tube)

A colourless fuming gas is evolved which gave white dense fumes when a glass rod dipped in ammonium hydroxide is shown Action with conc.

Sulphuric acid and paper ball

Plenty of reddish brown gas is evolved

Action with barium chloride solution (salt solution)

A white ppt insoluble in HCl acid is obtained

action with ammonium molybdate solution (nitric acid + excess of ammonium molybdate + soln)

A deep yellow colour or precipitate is formed

Carbonate: Soln + Barium chloride soln

A white precipitate is obtained which dissolved in dil. HCl with brisk effervescence

Acetate: soln + neutral ferric chloride soln

Soln + dil. Nitric acid + silver nitrate soln

A white curdy precipitate is formed which dissolved in excess of ammonium hydroxide soln salt + conc. Sulphuric

acid + manganese dioxide + heat

A greenish yellow gas with irritating smell is evolved which turned starch paper blue Nitrate: soln + freshly

prepared ferrous sulphate soln + conc. Sulphuric acid along the sides of the test tube without shaking

A brown ring is formed at the junction

A thick white precipitate is formed which dissolved in ammonium acetate soln

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Soln + lead nitrate soln

Phosphate: magnesia White crystalline ppt

Identification Tests

Confirmatory Tests

A brown ppt

Preparation of solution for the analysis of basic radical - stock soln

Grpup 1

Dil. HCl + dil. Nitric acid

Potassium iodide soln

Group 2

Black ppt Yellow ppt Colour of soln Blue

Brown colour or ppt

Group 3

Reddish brown ppt White gelatinus ppt

Blue tinted ash

A white precipitate insoluble in hot water and soluble in ammonium acetate

Analysis of Basic Radicals (Group Analysis)

Action with sodium carbonate soln

Soluble in water and and no precipitate is formed on adding sodium carbonate solution

Soluble in water and a precipitate is formed on adding sodium carbonate soln

Soln + sodium hydroxide + heat

A colourless, punjent smelling gas giving dense white fumes when a glass rod dipped in conc. HCl is shown

Nessler's reagent (about 2mL)

White precipitate that dissolved on boiling and reappeared on cooling A golden yellow precipitate that dissolved on boiling with water and reappered in golden spangles on cooling

Dil. HCl + hydrogen sulphide

Ammonium hydroxide soln

A greenish blue precipitate is formed which dissolved in excess of ammonium hydroxide

Acetic acid + potassium ferrocyanide Ammonium chloride + ammonium hydroxide

(drops - excess) Sodium hydroxide (drops

- excess) A white gelatinus ppt soluble in excess of NaOH

Note: If a white ppt is obtained in group 3, the test may be repeated using a dil. Soln of the salt since there is a chance of zinc getting pptd as zinc hydroxide on the addition of ammonium hydroxide, if the soln is too concentrated.

Ash test: Conc nitric acid + cobalt nitrate + heat >>> Dip filter paper and

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Group 4

A white or greenish white ppt A flesh coloured ppt

NaOH

White ppt turns brown on keeping

Green tinted ash

Group 5

White ppt

Yellow ppt (BaCrO4)

Flame test

Pale green colouration Crimson

Brick red

Scanty white ppt (slowly)

Group 6 A white crystalline ppt Pink ash Blue ppt Hydrogen sulphide + ammonium chloride + excess ammonium hydroxide

White ppt dissolves in excess of NaOH

Ash test: Conc nitric acid + cobalt nitrate + heat >>> Dip filter paper and

burn

Conc. Nitric acid + lead dioxide + heat. The soln

is cooled

The supernatent liquid got purple colour

Ammonium chloride + ammonium hydroxide +

ammonium carbonate (excess)

Above ppt + acetic acid + potassium chromate

Ammonium chloride + ammonium hydroxide +

ammonium oxalate

White crystalline ppt insoluble in acetic acid

Acetic acid + calcium sulphate + heat Ammonium chloride + ammonium hydroxide + disodium hydrogen phosphate

Ash test: Conc nitric acid + cobalt nitrate + heat >>> Dip filter paper and

burn

Ammonium hydroxide

soln A white ppt dissolves in excess ammonium OH Magneson reagent +

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Inference

Experiment Fe, Mn, Cu, Co and Ni salts are absent Flame test May be Cu, Ni or Cr salt

Confirmatory Anions May be ferrous salt

May be Mn salt May be ferric salt

Group analysis Absence of Pb Presence of Pb Presence of carbonate Presence of sulphide Presence of sulphite Presence of nitrite Confirmatory Cations Presence of carbonate

Presence of nitrates of heavy metals Presence of zinc salts

Presence of acetate

Presence of sulphide or sulphite

Presence of thiosulphates

Copper Quantitative Analysis

Calcium Acid

Strontium Strong

NH4, K or Na present NH4, K or Na absent

(6)

Barium Strong

Potassium Weak

Weak

Analysis of Acid Radicals

DRY TESTS

Double Titration

Presence of acetate is identified Standardisation Absence of acetate

Estimation Presence of chloride is identified

Presence of nitrate Single Titration

Presence of sulphate Titration table

Presence of phosphate

Procedure - 2 marks Presence of carbonate is confirmed Pipette

Presence of acetate is confirmed Burette

Chloride: Indicator

Presence of chloride is confirmed

End point

Presence of nitrate is confirmed

Sulphate:

Presence of sulphate

Substance whose normality has to be found out

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Presence of sulphate

Presence of phosphate is confirmed

Presence of ammonium confirmed

Preparation of solution for the analysis of basic radical - stock soln

Presence of lead

Presence of copper or mercury identified Presence of cadmium or arsenic

Presence of copper

Ferric ion

Presence of aluminium ion

Presence of aluminium is confirmed (Group Analysis)

Presence of zeroth group - ammonium - alkali group metal

Absence of ammonium. Presence of non-alkali group metal

If a white ppt is obtained in group 3, the test may be repeated using a dil. Soln of the salt since there is a chance of zinc getting pptd as zinc hydroxide on the addition of ammonium hydroxide, if

(8)

Presence of zinc Presence of Mn ion Presence of zinc Presence of Mn ion Presence of Zinc Presence of Mn ion Group 5 Presence of Ba Presence of Sr Presence of Ca Presence of Sr Presence of Mg Presence of Mg is confirmed

(9)

Reagent Ion Conc. HCl

Barium chloride soln + dil. HCl Carbonate

Neutral ferric chloride soln Acetate

Dil. nitric acid + silver nitrate soln Chloride

Freshly prepared ferrous sulphate soln + conc. Sulphuric acid Nitrate Sulphate

Sodium carbonate 0 - ammonium

Dil. HCl 1 - lead

Through above soln pass hydrogen sulphide 2 - copper Ammonium chloride + excess ammonium hydroxide 3 - aluminium

Through the above solution pass hydrogen sulphide 4 - zinc/manganese

Through the col 11 solution pass ammonium carbonate soln 5 - barium/calcium

Through the col 11 solution pass disodium hydrogen phosphate soln 6 - magnesium

Nessler's reagent Ammonium

Acetic acid + potassium chromate OR KI Lead

Acetic acid + potassium ferrocyanide soln Copper

Ash test: cobalt nitrate + conc. Nitric acid Aluminium

do Zinc

Sodium hydroxide Manganese

Acetic acid + potassium chromate

Barium

Calcium

Magneson reagent Magnesium

Quantitative Analysis

Base Indicator

Strong HPh

(10)

Weak MeOH

Strong HPh

Weak HPh / MeOH

Double Titration

Supplied soln v/s link soln Normality of link soln

Supplied soln v/s estimation soln

Normality of estimation soln

Single Titration

Supplied soln v/s est. soln

Mass of est. soln = Neq; Mass in the whole of the given soln = mass/10

Normality of est. soln; Strength of est. soln = Neq

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Ash Test

Aluminium Blue tinted ash

Zinc Green

Magnesium Pink

Eqiuvalent Mass Molecular Mass

NaOH 40.0 40.0 KOH 56.0 56.0 53.0 106.0 63.0 126.0 63.0 63.0 49.0 98.0 69.1 138.2 HCl 36.5 36.5 49.0 294.0 Na2CO3 H2C2O4.2H2O HNO3 H2SO4 K2CO3 K2Cr2O7

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