Salt Analysis Chart

SEMI – MICRO QUALITATIVE ANALYSIS OF SIMPLE INORGANIC SALT

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1. Note the state (amorphous or crystalline) and colour of salt. 2. Test the solubility of the salt in the following solutions: i. Water (cold and hot)

ii. Dilute HCl (cold and hot) iii. Dilute HNO3 (cold and hot)

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IDENTIFICATION OF ACID RADICALS (ANIONS)

This part is the classified into three groups:

FIRST GROUP OF ACID RADICALS

The acid radicals involved in this group are carbonate(CO32-), Sulphide(S2-), Sulphite(SO32-),

Thiosulphate(S2O32-) and nitrate(NO2-). The group reagent is dilute hydrochloric acid.

EXPERIMENT OBSERVATION INFERENCE

Effervescence or evolution of gases 1st _{group of acid radicals is present.}

(a) Colourless, odourless gas turns lime water

milky The acid radical may be CO32- or HCO3

-(b) Colourless with rotten eggs smell and turns

lead acetate paper black. Sulphide(S2-) is confirmed.

(c) Colourless gas with suffocating smell. Heat and pass the gas through acidified K2Cr2O7

solution. The solution turns green SO3

2- _{is confirmed.}

(d) Colourless gas with suffocating smell with a yellow ppt. of sulphur in the test tube. Heat and pass the gas through acidified K2Cr2O7 solution.

The solution turns dark blackish green.

S2O32- is confirmed.

(e) Colourless gas followed by brown gas and it

turns starch iodide paper blue. NO2- is confirmed.

Salt + dil. HCl

-Tests to distinguish between CO32- and HCO3-

EXPERIMENT OBSERVATION INFERENCE (a) Lime water does not turn milky. CO32- is confirmed.

Salt + water, boil and pass the

gas through lime water _{(b) Lime water turns milky. HCO}

3- is confirmed.

Confirmation test for Acetate

EXPERIMENT OBSERVATION INFERENCE Salt solution + Neutral FeCl3 sol. Appearance of blood red colour. Acetate is confirmed

SECOND GROUP OF ACID RADICALS

The acid radicals involved in this group are Cl-_{, Br}- _{and NO}

3- . The group reagent is concentrated

sulphuric acid (H2SO4).

EXPERIMENT OBSERVATION INFERENCE

Effervescence with colourless or coloured gases 2_present nd group Acid radical is (a) Colourless gas with a pungent smell and gives dense

white fumes when a glass rod dipped in ammonium hydroxide (NH4OH) is exposed.

The Acid radical may be Cl

-(b) Brown gas and the solution is not blue. The acid radical may be Br

Salt + Concentrated H2SO4 and heat

if necessary.

(c) Light brown gas and brown gas with pieces of copper

turnings and the solution turns blue in the test tube. The Acid radical may be NO3 -Confirmation test for Chloride

EXPERIMENT OBSERVATION INFERENCE

(a) Chromyl – Chloride test: Salt + few K2Cr2O7 crystals + conc. H2SO4 and heat

which contains NaOH solution.

To this yellow solution, add dilute CH3COOH and lead acetate solution.

Red vapours are obtained. The solution turns yellow. Yellow ppt. is formed

Chloride is confirmed.

(b) Silver Nitrate test: Salt solution + AgNO3 solution + dilute HNO3

White ppt. is formed

Confirmation test for Bromide

EXPERIMENT OBSERVATION INFERENCE

(a) Globule Test: Aqueous solution of salt + two drops of CCl4 + 1ml chlorine water and shake

well.

An orange-red globule is

obtained Bromide is confirmed.

(b)Silver Nitrate test: Salt solution + AgNO3

solution + dilute HNO3

A pale yellow ppt. slightly soluble

in NH4OH is obtained. Bromide is confirmed.

Confirmation test for Nitrate

EXPERIMENT OBSERVATION INFERENCE

Brown ring test: Strong solution of the substance + 2 or 3 drops of conc. H2SO4, and cool. Add freshly prepared

FeSO4 solution on the sides of the test tube.

A brown ring is formed at the junction of two liquids.

Nitrate is confirmed.

THIRD GROUP OF ACID RADICALS

The basic radicals involved in this group are SO42- and PO43- .

EXPERIMENT OBSERVATION INFERENCE

Test for Sulphate: Aqueous solution of salt + dilute HCl + BaCl2 solution.

A white ppt. insoluble in dilute

HCl is obtained Sulphate (SO4

2-_{) is}

confirmed. Ammonium – Molybdate Test: 2ml of soda extract1 ₊

dilute HNO3 + Ammonium Molybdate solution.

A canary yellow precipitate is obtained.

Phosphate (PO43-) is

confirmed.

ANALYSIS OF BASIC RADICALS OR CATIONS

This is classified into 6 groups. They are mentioned as below:

GROUP

RADICALS

GROUP REAGENTS

I Pb2+ _,Ag+ _{Dilute Hydrochloric acid(HCl)}

II Pb2+ _,Hg2+ _,Cu2+ _,Cd2+ _{Dilute HCl + H} 2S gas. III Al3+ _,Fe2+ _{, Fe}3+ _NH 4Cl(s) + NH4OH IV Zn2+ _,Mn2+ _,Co2+ _,Ni2+ _NH 4Cl(s) + NH4OH + H2S gas V Ca2+ _,Sr2+ _,Ba2+ _NH 4Cl(s) + NH4OH + (NH4) 2CO3 VI Mg2+ _{, NH} 4+ -Nil-

Preparation of Original solution: A suitable solvent is found for the salt as given in the preliminary test. A few drops are used as solution.

Test for NH4+Radicals: This test is carried out before starting the analysis for the basic radicals.

EXPERIMENT OBSERVATION INFERENCE

(a) Salt + NaOH solution and heat it. Expose a glass rod dipped in conc. HCl to the gas and moist red litmus paper.

Colourless gas with a pungent smell is obtained.

Dense white fumes and moist red litmus paper turns blue

NH4+ may be present in the

salt (b) Original solution + Nesseler’s

reagent. Brown solution or ppt. is obtained NH4+ is confirmed.

FIRST GROUP OF BASIC RADICALS

The basic radicals of this group are Pb2+ _{& Ag}+ _{.The group reagent is dilute HCl.}

EXPERIMENT OBSERVATION INFERENCE

White ppt. is formed. May be Pb2+ _{& Ag}+

(a) ppt. dissolves in hot water. May be Pb2+

(1) Original solution + Dilute HCl Filter and add water to ppt.

(a) A yellow ppt. is formed.

Pb2+ _{is confirmed.}

(2) Original solution + Potassium Chromate solution.

(b) A brick red ppt. is formed. _Ag+ _{is confirmed.}

(3) Original solution + KCl sol. ppt. obtained + water and heat it.

A yellow ppt. soluble in hot water, on cooling reappears as

golden yellow spangles. _Pb2+ _{is confirmed.}

The yellow ppt. is insoluble in hot water.

SECOND GROUP OF BASIC RADICALS

The basic radicals of this group are Pb2+_{, Hg}2+_{, Cu}2+ _{and Cd}2+_{.The group reagent is Dilute HCl + H}

2S gas.

EXPERIMENT OBSERVATION INFERENCE

May be Pb2+ _Hg2+ _{& Cu}2+

(a)A Black ppt. is observed. Original solution + Dilute HCl +

H2S gas. _{(b)A yellow ppt. is observed. May be Cd}2+

The identification of Pb2+_{, Hg}2+_{, Cu}2+ _{and Cd}2+ _{are as follows:}

EXPERIMENT OBSERVATION INFERENCE

(a) Original solution + Potassium

Chromate. A yellow ppt. is observed. Pb2+ is confirmed.

(b)Original solution + NH4OH

A bluish white ppt. soluble in excess of NH4OH is observed which gives

rise to a deep blue solution.

May be Cu2+

(c) Original solution + dil. acetic

acid + potassium Ferro cyanide sol. A chocolate red ppt. is observed. Cu2+ is confirmed. (d) Dissolve the black ppt. in aqua

regia2 _{+ 1ml of distilled water,}

heat & add 2 drops of SnCl2

A white ppt. is observed which turns

grey. Hg2+ is confirmed.

(e) Original solution + dilute acetic

acid + H2S gas. A yellow ppt. is formed. Cd2+ is confirmed.

THIRD GROUP OF BASIC RADICALS

The basic radicals of this group are Al3+_{, Fe}2+ _{and Fe}3+ _{.The group reagent is NH}

4Cl + NH4OH

EXPERIMENT OBSERVATION INFERENCE

May be Al3+

(a) A white gelatinous ppt. is obtained.

(b) A dirty green ppt. is obtained May be Fe2+

(1) Original solution + NH4Cl(s) + NH4OH in

excess _{(c) A reddish brown ppt. is obtained May be Fe}3+

(a) White gelatinous ppt. soluble in excess of NaOH

is obtained which gives a colourless sol. The basic radical is Al3+ (b) Dirty green ppt. insoluble in excess of NaOH The basic radical is Fe2+

(2) Original solution + NaOH solution

(c) Reddish brown ppt. insoluble in excess of NaOH The basic radical is Fe3+

(3) Clear solution of 2(a) + solid NH4Cl and

heat

The white gelatinous ppt. reappears. Al3+ _{is confirmed.}

(4) Original solution + acidified KMnO4 solution

which is added drop wise.

(a) The pink colour of KMnO4 is not discharged. Fe3+ is confirmed.

FOURTH GROUP OF BASIC RADICALS

The basic radicals of this group are Zn2+_{, Mn}2+_{, Co}2+ _{& Ni}2+_{.The group reagent is NH}

4Cl + NH4OH

And H2S(g).

EXPERIMENT OBSERVATION INFERENCE May be Zn2+_{, Mn}2+ _{or Co}2+

(a) a white ppt. is obtained (1) Original solution + NH4Cl(s)

+ NH4OH in excess + H2S(g) (b) Buff or pale pink or flash coloured ppt.

soluble in dilute HCl is obtained. May be Mn2+

(a) The white ppt. is soluble in excess of

NaOH giving a colourless solution. Zn2+ is confirmed

(2) Original solution + NaOH

solution+. _{(b) The white ppt. insoluble in excess of}

A Blue colour in the alcohol layer is obtained.

FIFTH GROUP OF BASIC RADICALS

The basic radicals of this group are Ca2+_{, Sr}2+ _{& Ba}2+ _{.The group reagent is NH}

4Cl(s) + NH4OH and

(NH4)2 CO3.

EXPERIMENT OBSERVATION INFERENCE

(1) Original solution + NH4Cl(s) + NH4OH in

excess + (NH4)2 CO3 solution. (a) A white ppt. is obtained.

May be Ca2+_{, Sr}2+ _or

Ba2+

A yellow ppt. is obtained. May be Ba2+ _.

A thin white ppt. is obtained. May be Sr2+ _.

(2) Dissolve the white ppt. obtained in small amounts of dilute acetic acid. Divide the solution in three parts.

Part (1) + Potassium chromate solution. Part (2) + Calcium Sulphate Sol. and heat.

Part (3) + Ammonium exalate solution. A white ppt. is obtained. May be Ca2+ _.

(a) Apple green coloured flame is

obtained. Ba2+ is confirmed.

(b) Crimson red coloured flame is

obtained. Sr2+ is confirmed.

(3)Flame tests: Make a paste of the given salt with few drops of Conc. HCl in a watch glass. Heat a Pt. wire in non luminous flame till no colour is imparted to the flame. Dip the Pt. wire in the paste and hold it in the

flame. (c) Brick red coloured flame is

obtained, Ca2+ is confirmed.

SIXTH GROUP OF BASIC RADICALS

EXPERIMENT OBSERVATION INFERENCE

(1) Original solution + excess of NH4OH +

Ammonium Hydrogen Phosphate. A white ppt. is obtained. Mg2+ is confirmed.

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Co2+ _{is confirmed}

(3) Dissolve the 1(a) in aqua regia, evaporate to Dryness, add 1ml of distilled water and divide the resultant product into two parts.

Part (1) + 1 ml of amyl alcohol + 100 mg of solid NH4SCN and stir it.

Part (2) + 5 drops of dimethyl glyaxime reagent +

NH4OH. A pink ppt. is obtained. Ni