Chemistry Lab Test for Cations

Identification test of Group 0 Ammonium (NH4+)

To a little of the salt solution sodium carbonate solution is added

observation

no precipitate

presence of group 0 (NH4+).

group 0 confirmatory 1

To a little of the salt solution NaOH solution is added

observation

colorless gas with smell of ammonia which gives dense white fumes with conc. HCl

presence of NH4+ is confirmed.

group 0 confirmatory 2

To a little of the salt solution nessler’s reagent is added

observation

brown precipitate formed

NH4+ confirmed.

Identification test for group 1 (Pb2+)

To a little of the salt solution dil. HCl is added

observation

white precipitate formed

presence of group 1 (Pb2+) identified.

group 1 confirmatory 1

To a little of the salt solution postassium iodide solution is added

observation

yellow precipitate soluble in water that reappear as golden spangles on cooling

presence of Pb 2+ is confirmed.

group 1 confirmatory 2

To a little of the salt solution acetic acid and potassium chromate solutions are added

observation

yellow precipitate

Pb 2+ confirmed

Identification test for group 2 (Cu2+)

To a little of the salt solution dil. HCl is added and hydrogen sulphide gas is passed

observation

black precipitate formed

presence of group 2 (Cu2+) is identified.

group 2 confirmatory 1

To a little of the salt solution NH4OH is added drop by drop till in excess

observation

blue precipitate soluble in excess of NH4OH to give deep blue solution

presence of Cu2+ confirmed.

group 2 confirmatory 2

To a little of the salt solution acetic acid and potassium ferrocyanide solutions are added

observation

chocolate brown precipitate

Cu2+ confirmed

Identification test for group 3 (Al3+)

To a little of the salt solution excess of NH4OH and NH4Cl are added

observation

white gelatinous precipitate

presence of group 3(Al3+).

group 3 confirmatory 1

To a little of the salt solution NaOH solution is added drop by drop till in excess

observation

white gelatinous precipitate soluble in excess of NaOH is formed

presence of Al3+ confirmed.

group 3 confirmatory 2

Ash test

To a little of the salt solution one to two drops of conc. HNO3 and cobalt nitrate solutions are added. It is then boiled and a filter paper dipped in it is burned to ashes

observation

blue tinted ash

Al3+ is confirmed.

Identification test for group 4 (Zn2+)

To a little of the salt solution excess of NH4OH and NH4Cl are added and hydrogen sulphide gas is passed

observation

white precipitate

presence of group 4 (Zn2+) is identified.

group 4 confirmatory 1

To a little of the salt solution excess of NaOH solution is added

observation

white precipitate soluble in excess of NaOH

presence of Zn2+ confirmed.

group 4 confirmatory 2

Ash Test

To a little of the salt solution one to two drops of conc. HNO3 and cobalt nitrate solution. It is boiled and a filter paper dipped in it is burnt to ashes

observation

green tinted ash

Zn2+ is confirmed

Identification test for group 5 (Ca2+ or Ba2+)

To a little of the salt solution add NH4OH, NH4Cl and (NH4)2CO3

observation

white precipitate

presence of group 5 (Ca2+ or Ba2+).

group 5 confirmatory 1 (a)

To a little of the salt solution acetic acid and potassium chromate solutionsare added

observation

yellow precipitate

presence of Ba2+ is confirmed

group 5 confirmatory 2 (a)

A little of the substance is made into a paste with conc. HCl in a watch glass. Then a glass rod dipped in it is shown into the non luminous flame

observation

green flame

Ba2+ confirmed.

group 5 confirmatory 1 (b)

To a little of the salt solution acetic acid and potassium chromate solutions are added

observation

no precipitate

presence of Ca2+ ions.

group 5 confirmatory 2 (b)

To a little of the salt solution NH4OH and ammonium oxalate are added

observation

white precipitate

presence of Ca2+ ion confirmed.

group 5 confirmatory 3 (b)

Flame Test

A little of the salt is made into a paste with conc. HCl in a watch glass. Then a glass rod dipped in it is shown to the non luminous flame

observation

Brick-red flame

Ca2+ confirmed.

Identification test for group 6 (Mg2+)

To a little of the salt solution NH4OH, NH4Cl and Na2HPO4 are added

observation

white crystalline precipitate

presence of group 6 (Mg2+) identified.

group 6 confirmatory 1

To a little of the salt solution magneson reagent and excess NaOH solution is added

observation

blue precipitate

presence of Mg2+ confirmed.

group 6 confirmatory 2

Ash Test

To a little of the salt solution one to two drops of conc. HNO3 and cobalt nitrate solution is added. It is boiled then a filter paper dipped in it is burnt to ashes

observation

pink tinted ash

Mg2+ is confirmed.