Aim	To qualitatively determine one cation and one anion in a given salt using chemical tests.
Apparatus Required	Unknown salt Dilute hydrochloric acid (HCl) Dilute nitric acid (HNO3) Ammonium hydroxide (NH4OH) Sodium hydroxide (NaOH) Barium chloride (BaCl2) solution Silver nitrate (AgNO3) solution Potassium chromate (K2CrO4) solution Filter paper Test tubes Bunsen burner Dropper Wire loop
Theory	In this experiment, a salt containing one cation and one anion is qualitatively analyzed using different chemical tests. The presence of cations and anions is identified by the formation of precipitates, color changes, or gas evolution. The following tests are used to determine the cation and anion present in the salt: Cation tests: Flame test: Each cation produces a characteristic flame color when heated in the flame of a Bunsen burner. Precipitation test: A cation can be identified by adding a solution of a specific reagent to the salt solution, which results in the formation of a characteristic precipitate. Hydroxide test: The cation can be identified by adding ammonium hydroxide solution to the salt solution, which results in the formation of a characteristic precipitate. Anion tests: Precipitation test: An anion can be identified by adding a solution of a specific reagent to the salt solution, which results in the formation of a characteristic precipitate. Acidification test: An acid is added to the salt solution to liberate the anion as a gas, which can be identified by its characteristic odor. Neutralization test: An anion can be identified by adding a solution of a specific reagent to the salt solution, which results in the formation of a characteristic precipitate. NaOH + HCl → NaCl + H2O CO2 + 2NaOH → Na2CO3 + H2O KOH + HNO3 → KNO3 + H2O 2NaOH + H2SO4 → Na2SO4 + 2H2O
Procedure	Take a small amount of the unknown salt in a test tube and add a few drops of dilute hydrochloric acid (HCl). If the salt dissolves, move to step 2. If not, add a few drops of dilute nitric acid (HNO3) to dissolve the salt. Perform the cation tests one by one until the cation is identified. Record observations for each test. Flame test: Dip a wire loop in hydrochloric acid and then in the salt. Hold the loop in the Bunsen burner flame and observe the color of the flame. Precipitation test: Add a few drops of barium chloride (BaCl2) solution to the salt solution and observe the formation of a precipitate. Hydroxide test: Add ammonium hydroxide (NH4OH) solution to the salt solution and observe the formation of a precipitate. Once the cation is identified, perform the anion tests one by one until the anion is identified. Record observations for each test. Precipitation test: Add a few drops of silver nitrate (AgNO3) solution to the salt solution and observe the formation of a precipitate. Acidification test: Add dilute hydrochloric acid (HCl) to the salt solution and observe any gas evolved. Neutralization test: Add a few drops of potassium chromate (K2CrO4) solution to the salt solution and observe the formation of a precipitate. Confirm the cation and anion present in the salt by performing the cation and anion tests again.

Procedure to be followed

Identification of Anions

S.No	Experiment	Observation	Inference
1	Preliminary reactions	The given salt is colorless. <br>- Green salt: may contain Fe2+, Ni2+, Cu2+. <br>- Brown salt: may contain Fe2+. <br>- Pink salt: may contain Co2+, Mn2+. <br>- Blue salt: may contain Cu2+.	Presence or absence of certain cations can be determined based on the color of the salt.
2	Action of Heat	– Colorless gas with a pungent odor that turns moist red litmus blue paper. <br>- Reddish brown vapors that turn acidified ferrous sulfate brown paper. <br>- In cold, the substance is white and in hot, yellow.	Presence of NH4+, NO3–, or (Zn)2+ ions can be determined based on the observations.
3	Flame Test	Apple green color flame. <br>- Crimson red color flame. <br>- Brick red color flame. <br>- Bluish green flame.	Presence of Ba2+, Sr2+, Ca2+, or Cu2+ ions can be determined based on the color of the flame.
4	Action of dilute.H2SO4	Brisk effervescence is obtained from colorless, odorless gas that turns lime water. <br>- Colorless gas with an odor of rotten eggs is obtained, turning lead acetate black paper. <br>- Colorless gas with the odor of burning sulfur that turns acidified dichromate green. <br>- Reddish brown gas is obtained with a fishy odor that turns acidified brown ferrous sulfate. <br>- Colorless vinegar-flavored gas is obtained. <br>- No characteristic observation.	Presence of CO32-, sulphide, sulfate, nitrate, or acetate anions can be determined based on the observations.
5	Action of Con. H2SO4 Add 1 or 2ccs of dilute H2SO4 to a small portion of the salt in a test tube and warm it gently.	Reddish-brown vapors that turn moist red paper fluorescent. <br>- Colorless gas with a pungent smell that provides dense white fumes with a dipped glass rod in NH4OH solution. <br>- Violet-colored vapors that turn blue or violet starch paper. <br>- Reddish-brown vapors turning brown ferrous sulfate paper into acidified. <br>- No characteristic observation.	Presence of bromide, chloride, iodide, or nitrate anions can be determined based on the observations
6	Action of Con. H2SO4 with Cu turnings Mix with a few Cu bits a small amount of the salt taken in a test tube, add 2 – 3 ccs of H2SO4 and heat it.	Copious evolution of reddish-brown gas turning acidified ferrous sulfate paper brown. <br>- No reddish-brown vapors.	Presence or absence of nitrate anions can be determined based on the observations
7	Action of Con. H2SO4 with MnO2 Add an equal amount of MnO2 to a small amount of salt in a test tube and add a few ccs of Con. H2SO4 and heat gently.	Greenish yellow gas turning violet (or) blue starch iodide paper. <br>- Reddish brown vapors are obtained that turn moist fluorescent red paper. <br>- Violet vapors are obtained that turn starch paper blue (or) violet. <br>- No characteristic colored vapors are obtained.	Presence or absence of chloride, bromide, or iodide anions can be determined based on the observations.
8	Action of NaOH Add a few ccs of 10% NaOH solution to a pinch of salt taken in a test tube and warm it gently.	It is obtained a colorless gas with a pungent smell that produces dense white fumes with a glass rod dipped in HCl. There is no characteristic gas released from ammonium. Absence of ammonium.	May be ammonium ion. Absence of ammonium.

To confirm the presence of certain anions, two types of extracts are used: a water extract for water-soluble salts, and a sodium carbonate extract for water-insoluble salts. To detect CO32–, the aqueous salt solution or solid salt can be used, as carbonate ions are present in the sodium carbonate extract. The water extract is prepared by dissolving the salt in water.

To prepare the sodium carbonate extract, take 1g of the salt in a boiling tube or porcelain dish, and mix about 3g of solid sodium carbonate with 15mL of distilled water. Boil the mixture for 10 minutes, let it cool, filter it, collect the filtrate in a test tube, and label it as the sodium carbonate extract.

9	Silver nitrate test: Add dilute HNO3 to a portion of the sodium carbonate extract until the effervescence stops. Add a few drops of AgNO3 solution in excess, 2 – 3nos.	Curdy white NH4OH soluble precipitate. Pale yellow precipitate in NH4OH that is sparingly soluble. Insoluble yellow precipitation in NH4OH. No characteristics precipitate.	May be chloride anion. May be bromide anion. May be iodide anion. Absence of all above mentioned anions.
10	Barium Chloride test: Add BaCl2 solution to about one or two ccs of the extract (after acetic acid neutralization and CO2 boiling). Add dilute hydrochloric acid to a portion of the ppt above.	An insoluble white precipitate in HCl. A HCl soluble white precipitate. No characteristics precipitate.	The anion is SO42 The anion is SO32- Absence of SO42- and SO32-.
11	Lead acetate test: Add lead acetate solution to about one or two ccs of the extract (after acidification with acetic acid, CO2 boiling off and cooling).	White ppt, soluble in excess of the solution of ammonium acetate.	Presence of SO42- is confirmed.
12	Ferrous Sulphate Test: (Also called Brown ring test) Add dilute H2SO4 in drops to about 1 or 2cc of extract until the effervescence stops. And a few drops in excess add two to three drops of freshly prepared FeSO4 solution. Keep in a slanting position the test tube, add Con. H2SO4 without interfering with the solution	At the liquid junction, a brown ring is obtained. . No brown ring formed	Nitrate anion (NO3–) is present Nitrate anion (NO3–) is absent.
13	Ferric chloride test: Take the extract in a test tube for about 1 or 2ccs and add a neutral FeCl3 solution. If necessary, filter and split the solution or filtrate into two parts: 1. Add dil. HCl 2. Add water and boil to the second part	Deep red colouring produced. Red colouring is gone. Reddish brown precipitate.	Acetate anion is confirmed. (CH3COO–) CH3COO– is confirmed. CH3COO– is confirmed.
14	Calcium Chloride Test: In a test tube, add dil to a portion of the extract of sodium carbonate. Boil off CO2 with acetic acid. Add a few drops of a solution of calcium chloride. Incorporate dil. HNO3 to the hot and white ppt	A white calcium oxalate precipitate is obtained. Precipitate dissolves.	Confirms the presence of oxalate anion.
15	Ethyl Acetate Test: Add a few drops of ethanol to a pinch of salt taken in a test tube, followed by 1 or 2ccs of H2SO4. Heat it gently and cool it down. Version Na2CO3.	There is a pleasant fruity odor.	It is confirmed that anion acetate is present.

Observation and Results

S.No	Anions	Observation
1	CO32‒ (Carbonate anion)	CO2 gas is evolved with brisk effervescence with dilute sulphuric acid, which turns lime water milky.
2	S2‒ (Sulphide anion)	Add a drop of solution for sodium nitroprusside. Appears purple or violet colouring.
3	SO32‒ (Sulfite anion)	A white precipitate is formed with a barium chloride solution that dissolves in dilute hydrochloric acid and sulfur dioxide gas also develops.
4	SO42‒ (Sulfate anion)	Take 1 mL of salt water extract in water or sodium carbonate and add BaCl 2 solution after acidification with dilute hydrochloric acid. Insoluble white precipitate in conc. HCl or HCl. It gets HNO3.
5	NO2‒ (Nitrite anion)	Add a few drops of iodide potassium solution and a few drops of starch solution, acidify with acetic acid. Blue colour appears.
6	NO3‒ (Nitrate anion)	Take in a test tube 1 mL of salt solution in water. Add a conc of 2 mL. Mix thoroughly with H2SO4. Cool the mixture under the tap. Add freshly prepared ferrous sulfate without shaking on the sides of the test tube. At the junction of the two solutions, a dark brown ring is formed.
7	Cl‒ (Chloride anion)	In a test tube, take 0.1 g of salt, add a pinch of manganese dioxide and 3-4 drops of conc. Acid with sulfuric acid. Heat the mixture of reactions. Greenish yellow chlorine gas that is detected by its strong odor and bleaching action
8	Br‒ (Bromide anion)	Take 0.1 g of salt in a test tube with a pinch of MnO2. Add conc.sulphuric acid and heat with 3-4 drops. There is an evolution of intense brown fumes.
9	I‒ (Iodide anion)	Take in a test tube 1 mL of salt solution in water. Add a conc of 2 mL. Mix thoroughly with H2SO4. Cool under the tap the mixture. Add freshly prepared ferrous sulfate without shaking on the sides of the test tube. At the junction of the two solutions, a dark brown ring is formed.
10	PO43‒ (Phosphate anion)	Acidify the extract of sodium carbonate or salt solution in water and con HNO3 and add solution of ammonium molybdate and heat to boil. A precipitate canary yellow is formed.
11	C2O42‒ (Oxalate anion)	Take 1 mL of acetate acidified water extract or sodium carbonate extract and add a solution of calcium chloride. An insoluble white precipitate is formed in the solution of ammonium oxalate and oxalic acid but soluble in dilute hydrochloric acid and diluted nitric acid.
12	CH3COO‒ (Acetate anion)	Add 1 mL and 0.2 mL conc of ethanol. Heat and H2SO4. The presence of acetate ion is confirmed by fruity odor.