Chemistry Practical Help for xii

Experiment Preliminary Tests

Observation

Colourless Blue, bluish green or green Colour and appearance Pale green Pink Brown or yellow

Solubility in water

Water soluble and no precipitate with Na2CO3 solution Water soluble and precipitate with Na2CO3 solution

Solubility in/action of dil. Soluble HCl Insoluble

Brisk effervescence If insoluble in water the salt Colourless gas with the smell of is treated with dil. HCl rotten eggs is evolvedwhich turned lead acetate paper black Colourless, suffocating smelling gas which turned acidified potassium dichromate paper green is evolved Brown fumes evolved Action of heat Colourless, odourless gas turning lime water milky Brown fumes with irritating smell Residue yellow when hot and white when cold Pleasant smell of inflammable Heat strongly a little of the vapours are evolved salt in a dry test tube A colourless gas with smell of burnt sulphur evolved which turned acidified potassium dichromate paper green Smell of burnt sulphur and yellow sublimate Flame test

Blue or bluish green colour

Brick red colour Paste of salt and conc. HCl is introduced into Bunsen Crimson flame

Paste of salt and conc. HCl is introduced into Bunsen flame

Light green colour Liliac (violet) Analysis of Acid Radicals

Identification Tests

Action of dil. HCl (about 1mL) Action of dil. Sulphuric acid (watch glass)

Refer to row no. 10 Vinegar smell is obtained No characteristic reaction

A colourless fuming gas is evolved Action of conc. Sulphuric which gave white dense fumes acid (heating in a dry test when a glass rod dipped in tube) ammonium hydroxide is shown Action with conc. Plenty of reddish brown gas is Sulphuric acid and paper evolved ball Action with barium chloride solution (salt solution)

A white ppt insoluble in HCl acid is obtained

action with ammonium molybdate solution A deep yellow colour or precipitate (nitric acid + excess of is formed ammonium molybdate + soln)

Confirmatory Tests

Carbonate: Soln + Barium chloride soln Acetate: soln + neutral ferric chloride soln Chloride:

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

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. A brown ring is formed at the Sulphuric acid along the junction sides of the test tube without shaking Sulphate: A thick white precipitate is formed Soln + lead acetate soln which dissolved in ammonium acetate soln

Soln + lead nitrate soln Phosphate: magnesia

Identification Tests

Confirmatory Tests

A white precipitate insoluble in hot water and soluble in ammonium acetate White crystalline ppt

Analysis of Basic Radicals (Group Analysis) Soluble in water and and no precipitate is formed on adding sodium carbonate solution Action with sodium carbonate soln Soluble in water and a precipitate is formed on adding sodium carbonate soln A colourless, punjent smelling gas Soln + sodium hydroxide giving dense white fumes when a + heat glass rod dipped in conc. HCl is shown Nessler's reagent (about A brown ppt 2mL) Preparation of solution for the analysis of basic radical - stock soln Dil. HCl + dil. Nitric acid

Grpup 1

A golden yellow precipitate that dissolved on boiling with water and Potassium iodide soln reappered in golden spangles on cooling Dil. HCl + hydrogen sulphide Colour of soln

Group 2

White precipitate that dissolved on boiling and reappeared on cooling

Ammonium hydroxide soln

Black ppt Yellow ppt Blue A greenish blue precipitate is formed which dissolved in excess of ammonium hydroxide

Acetic acid + potassium Brown colour or ppt ferrocyanide Ammonium chloride + ammonium hydroxide (drops - excess)

Reddish brown ppt

White gelatinus ppt Sodium hydroxide (drops A white gelatinus ppt soluble in - excess) excess of NaOH Group 3

Note: If a white ppt is obtained in group 3, the test may be repeated using a dil. Soln of the salt sin there is a chance of zinc getting pptd as zinc hydroxide on the addition of ammonium hydroxide, the soln is too concentrated. Ash test: Conc nitric acid + cobalt nitrate + heat Blue tinted ash >>> Dip filter paper and burn

Hydrogen sulphide + ammonium chloride + excess ammonium hydroxide

NaOH

A white or greenish white ppt A flesh coloured ppt White ppt dissolves in excess of NaOH White ppt turns brown on keeping

Group 4

Ash test: Conc nitric acid + cobalt nitrate + heat Green tinted ash >>> Dip filter paper and burn Conc. Nitric acid + lead The supernatent liquid got purple dioxide + heat. The soln colour is cooled Ammonium chloride + ammonium hydroxide + White ppt ammonium carbonate (excess) Above ppt + acetic acid + Yellow ppt (BaCrO4) potassium chromate Group 5

Flame test

Pale green colouration Crimson Brick red

Ammonium chloride + White crystalline ppt insoluble in ammonium hydroxide + acetic acid ammonium oxalate Acetic acid + calcium sulphate + heat Ammonium chloride + ammonium hydroxide + disodium hydrogen phosphate Group 6

Scanty white ppt (slowly)

A white crystalline ppt

Ash test: Conc nitric acid + cobalt nitrate + heat Pink ash >>> Dip filter paper and burn Ammonium hydroxide soln Magneson reagent + excess NaOH

A white ppt dissolves in excess ammonium OH Blue ppt

Inference Fe, Mn, Cu, Co and Ni salts are absent May be Cu, Ni or Cr salt May be ferrous salt May be Mn salt May be ferric salt

Experiment Flame test

Confirmatory Anions

NH4, K or Na present NH4, K or Na absent Absence of Pb Presence of Pb Group analysis Presence of carbonate

Presence of sulphide

Presence of sulphite Presence of nitrite

Presence of carbonate Presence of nitrates of heavy metals Presence of zinc salts Confirmatory Cations Presence of acetate

Presence of sulphide or sulphite

Presence of thiosulphates

Quantitative An

Copper Calcium Strontium

Acid Strong

Strong Weak Weak

Barium Potassium

dicals

DRY TESTS Presence of acetate is identified

Double Titrat Standardisation

Absence of acetate

Presence of chloride is identified

Estimation

Presence of nitrate

Presence of sulphate

Single Titrati

Titration table

Presence of phosphate

Procedure - 2 marks Presence of carbonate is confirmed

Pipette

Presence of acetate is confirmed

Burette Indicator End point

Presence of chloride is confirmed Substance whose normality has to be found out

Presence of nitrate is confirmed

Presence of sulphate

Presence of sulphate

Presence of phosphate is confirmed

Group Analysis) Presence of zeroth group - ammonium alkali group metal Absence of ammonium. Presence of nonalkali group metal

Presence of ammonium confirmed

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

est may be repeated using a dil. Soln of the salt since droxide on the addition of ammonium hydroxide, if

Presence of aluminium is confirmed

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

Reagent

Ion

Conc. HCl Barium chloride soln + dil. HCl Neutral ferric chloride soln Dil. nitric acid + silver nitrate soln Freshly prepared ferrous sulphate soln + conc. Sulphuric acid Lead acetate soln / lead nitrate soln + ammonium acetate

Carbonate Acetate Chloride 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 Acetic acid + potassium chromate OR KI Acetic acid + potassium ferrocyanide soln

Ammonium Lead Copper

Ash test: cobalt nitrate + conc. Nitric acid

Aluminium

do Sodium hydroxide

Zinc Manganese Barium

Acetic acid + potassium chromate Calcium

Magneson reagent

Magnesium Quantitative Analysis Base

Strong

Indicator HPh

Weak Strong Weak

MeOH HPh HPh / MeOH

Double Titration Supplied soln v/s link soln

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

Supplied soln v/s estimation soln

Single Titration

Supplied soln v/s est. soln

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

Ash Test Aluminium Zinc Magnesium

Blue tinted ash Green Pink Eqiuvalent Mass

Molecular Mass

NaOH

40.0

40.0

KOH

56.0

56.0

Na2CO3

53.0

106.0

H2C2O4.2H2O

63.0

126.0

HNO3

63.0

63.0

H2SO4

49.0

98.0

K2CO3

69.1

138.2

HCl K2Cr2O7

36.5

36.5

49.0

294.0