Scheme of Analysis of Simple Salt

Vocabulary flashcards covering preliminary tests, anion confirmatory tests, cation group separation, and specific confirmatory tests from the salt analysis scheme.

Colourless Salt Observation

Indicates the absence of copper, iron, manganese, cobalt, and nickel salts.

Flame Test (Barium)

A preliminary test where a salt paste with conc. $\text{HCl}$ produces a pale green coloured flame in a non-luminous Bunsen burner flame.

Flame Test (Calcium)

A preliminary test where a salt paste with conc. $\text{HCl}$ produces a brick red coloured flame in a non-luminous Bunsen burner flame.

Ash Test (Aluminium)

A test where the salt is heated with conc. $\text{HNO}_3$ and a few drops of cobalt nitrate solution, and filter paper soaked in this solution is burnt to yield a blue ash.

Ash Test (Zinc)

A test where the salt is heated with conc. $\text{HNO}_3$ and a few drops of cobalt nitrate solution, and filter paper soaked in this solution is burnt to yield a green ash.

Ash Test (Magnesium)

A test where the salt is heated with conc. $\text{HNO}_3$ and a few drops of cobalt nitrate solution, and filter paper soaked in this solution is burnt to yield a light pink ash.

Dilute $\text{HCl}$ Test for Carbonate

Addition of dil. $\text{HCl}$ to the salt produces brisk effervescence of a colourless, odourless gas that turns lime water milky, identifying the presence of carbonate.

Dilute $\text{H}_2\text{SO}_4$ Test for Acetate

Rubbing salt with dil. $\text{H}_2\text{SO}_4$ in a watch glass produces the characteristic smell of vinegar, identifying the presence of acetate.

Concentrated $\text{H}_2\text{SO}_4$ Test for Chloride

Warming salt with conc. $\text{H}_2\text{SO}_4$ in a dry test tube evolves a colourless fuming gas which gives dense white fumes with $\text{NH}_4\text{OH}$.

Concentrated $\text{H}_2\text{SO}_4$ Test for Bromide

Warming salt with conc. $\text{H}_2\text{SO}_4$ in a dry test tube evolves reddish brown vapours with the formation of a red liquid.

Paper Ball Test

Heating salt with conc. $\text{H}_2\text{SO}_4$ in a dry test tube with an added paper ball evolves reddish brown vapours, identifying the presence of nitrate.

Barium Chloride Test for Sulphate

Adding barium chloride solution to salt solution produces a white precipitate insoluble in dilute $\text{HCl}$.

Neutral $\text{FeCl}_3$ Test for Acetate

A confirmatory test where adding neutral $\text{FeCl}_3$ solution to the salt solution produces a deep red colour.

Ester Test for Acetate

A confirmatory test where salt solution is warmed with $1\,\text{mL}$ conc. $\text{H}_2\text{SO}_4$ and about $2\,\text{mL}$ ethanol and poured into water, producing a pleasant fruity smell.

Silver Nitrate Test for Chloride

Adding a few drops of dil. $\text{HNO}_3$ and $\text{AgNO}_3$ solution to salt solution produces a white curdy precipitate soluble in $\text{NH}_4\text{OH}$ solution.

$\text{MnO}_2$ Test for Chloride

Warming salt with $\text{MnO}_2$ and a few drops of conc. $\text{H}_2\text{SO}_4$ produces a greenish yellow gas.

Silver Nitrate Test for Bromide

Adding a few drops of dil. $\text{HNO}_3$ and $\text{AgNO}_3$ solution to salt solution produces a pale-yellow precipitate partially soluble in $\text{NH}_4\text{OH}$.

$\text{MnO}_2$ Test for Bromide

Warming salt with $\text{MnO}_2$ and a few drops of conc. $\text{H}_2\text{SO}_4$ evolves reddish brown vapours that condense into a red liquid.

Brown Ring Test

A confirmatory test for nitrate where salt solution is mixed with an equal volume of freshly prepared ferrous sulphate solution and conc. $\text{H}_2\text{SO}_4$ is carefully added along the test tube side to form a brown ring between two layers.

Zinc Dust and $\text{NaOH}$ Test for Nitrate

Heating salt solution with zinc dust and $\text{NaOH}$ solution evolves a smell of ammonia, confirming the presence of nitrate.

Lead Acetate Test for Sulphate

Adding lead acetate solution to salt solution forms a white precipitate that dissolves when tested in ammonium acetate.

Analysis of Group Zero ($\text{NH}_4^+$)

Heating salt solution with sodium hydroxide solution evolves a colourless, pungent-smelling gas (smell of ammonia) that yields dense white fumes with conc. $\text{HCl}$.

Nessler's Reagent Test

A confirmatory test for ammonium ($\text{NH}_4^+$) where salt solution added to Nessler's reagent (or filter paper moistened with it shown to evolved gas) forms a brown precipitate or brown stain.

Group I Cations and Reagents

Includes $\text{Pb}^{2+}$, $\text{Ag}^+$, and $\text{Hg}^{2+}$; tested by adding dil. $\text{HCl}$ to form a white precipitate.

Potassium Chromate Test for Lead

Adding dilute acetic acid and potassium chromate solution to salt solution forms a yellow precipitate.

Potassium Iodide Test for Lead

Adding potassium iodide to salt solution forms a yellow precipitate soluble in hot water that reappears as golden yellow spangles.

Group II Cations and Reagents

Includes $\text{Cu}^{2+}$, $\text{Cd}^{2+}$, $\text{Sb}^{3+}$, and $\text{Bi}^{3+}$; tested by adding dil. $\text{HCl}$ and passing $\text{H}_2\text{S}$ gas to form a black precipitate.

Ammonium Hydroxide Test for Copper

Adding $\text{NH}_4\text{OH}$ dropwise in excess to salt solution forms a pale blue precipitate that dissolves in excess $\text{NH}_4\text{OH}$ to yield a deep blue solution.

Group III Cations and Reagents

Includes $\text{Al}^{3+}$, $\text{Fe}^{3+}$, and $\text{Cr}^{3+}$; tested by adding excess $\text{NH}_4\text{Cl}$ (crystals) and $\text{NH}_4\text{OH}$ to form a white gelatinous precipitate.

Group IV Cations and Reagents

Includes $\text{Zn}^{2+}$, $\text{Mn}^{2+}$, $\text{Co}^{2+}$, and $\text{Ni}^{2+}$; tested by adding excess $\text{NH}_4\text{Cl}$ (crystals), $\text{NH}_4\text{OH}$, and passing $\text{H}_2\text{S}$ gas (or $\text{Na}_2\text{S}$ solution) to form a white/dirty white precipitate.

Group V Cations and Reagents

Includes $\text{Ba}^{2+}$, $\text{Ca}^{2+}$, and $\text{Sr}^{2+}$; tested by adding excess $\text{NH}_4\text{Cl}$ (crystals), $\text{NH}_4\text{OH}$, and $\text{(NH}_4\text{)}_2\text{CO}_3$ to form a white precipitate.

Group VI Cation and Reagents

Includes $\text{Mg}^{2+}$; tested by adding excess $\text{NH}_4\text{Cl}$ (crystals), $\text{NH}_4\text{OH}$, and disodium hydrogen phosphate ($\text{Na}_2\text{HPO}_4$) to form a white crystalline precipitate.

Magneson Reagent Test

Adding magneson reagent and excess sodium hydroxide solution to salt solution produces a blue precipitate, identifying magnesium.