Podcast
Questions and Answers
In salt analysis, why are anions identified before cations?
In salt analysis, why are anions identified before cations?
- Anions react more readily with reagents.
- Anions are simpler to identify.
- Some anions interfere with the tests for cations. (correct)
- Cations do not affect anion identification.
Which of the following anions is NOT typically considered an interfering anion in salt analysis?
Which of the following anions is NOT typically considered an interfering anion in salt analysis?
- Fluoride ($F^-$)
- Borate ($BO_3^{3-}$)
- Oxalate ($C_2O_4^{2-}$)
- Chloride ($Cl^-$) (correct)
What is the correct order of steps in the systematic analysis of a salt?
What is the correct order of steps in the systematic analysis of a salt?
- Cation test, then Anion test
- Solubility test, then Cation test
- Preliminary test, then Confirmatory test (correct)
- Confirmatory test, then Preliminary test
Anions are classified into groups based on their reactivity with specific reagents. Which statement accurately describes a key difference between Class A and Class B anions?
Anions are classified into groups based on their reactivity with specific reagents. Which statement accurately describes a key difference between Class A and Class B anions?
What reagent is commonly used to classify anions into subgroups within Class A?
What reagent is commonly used to classify anions into subgroups within Class A?
Which of the following gases, when evolved from a salt treated with dilute HCl, turns lead acetate paper black?
Which of the following gases, when evolved from a salt treated with dilute HCl, turns lead acetate paper black?
A colorless, pungent gas is evolved when a salt is treated with concentrated $H_2SO_4$. The gas gives dense white fumes when a glass rod dipped in $NH_4OH$ is brought near. What anion is likely present?
A colorless, pungent gas is evolved when a salt is treated with concentrated $H_2SO_4$. The gas gives dense white fumes when a glass rod dipped in $NH_4OH$ is brought near. What anion is likely present?
Which of the following observations indicates the presence of a bromide ($Br^−$) ion in a preliminary test involving concentrated sulfuric acid ($H_2SO_4$)?
Which of the following observations indicates the presence of a bromide ($Br^−$) ion in a preliminary test involving concentrated sulfuric acid ($H_2SO_4$)?
When a salt is treated with concentrated $H_2SO_4$ and copper turnings, a brown gas evolves, and the solution turns blue. What anion is indicated by these observations?
When a salt is treated with concentrated $H_2SO_4$ and copper turnings, a brown gas evolves, and the solution turns blue. What anion is indicated by these observations?
Which of the following salts will produce a volatile product when reacted with dilute $H_2SO_4$?
Which of the following salts will produce a volatile product when reacted with dilute $H_2SO_4$?
A salt (X) reacts with dilute HCl to produce a gas (Y) that smells like rotten eggs. What are X and Y, respectively?
A salt (X) reacts with dilute HCl to produce a gas (Y) that smells like rotten eggs. What are X and Y, respectively?
A sodium salt (NaX) reacts with concentrated $H_2SO_4$ to produce brown vapors (Y), which form a brown solution when dissolved in $H_2O$. What are X and Y, respectively?
A sodium salt (NaX) reacts with concentrated $H_2SO_4$ to produce brown vapors (Y), which form a brown solution when dissolved in $H_2O$. What are X and Y, respectively?
Which of the following acidic radicals can interfere with the test for cations?
Which of the following acidic radicals can interfere with the test for cations?
Which of the following salts remains unaffected by concentrated $H_2SO_4$?
Which of the following salts remains unaffected by concentrated $H_2SO_4$?
In confirmatory tests, what is added to an unknown salt to make it soluble if it's not soluble in water?
In confirmatory tests, what is added to an unknown salt to make it soluble if it's not soluble in water?
Why is it necessary to neutralize the soda extract solution before performing tests?
Why is it necessary to neutralize the soda extract solution before performing tests?
The soda extract is not prepared for which of the following anions?
The soda extract is not prepared for which of the following anions?
What observation confirms the presence of $CO_3^{2-}$ in a confirmatory test?
What observation confirms the presence of $CO_3^{2-}$ in a confirmatory test?
In the confirmatory test for carbonate ions, which reagent is used to produce a white precipitate soluble in dilute HCl?
In the confirmatory test for carbonate ions, which reagent is used to produce a white precipitate soluble in dilute HCl?
What observation is made when $AgNO_3$ is added to a solution containing carbonate ions ($CO_3^{2-}$)?
What observation is made when $AgNO_3$ is added to a solution containing carbonate ions ($CO_3^{2-}$)?
Which reagent is used to detect sulfide ions ($S^{2−}$), producing a black spot on filter paper?
Which reagent is used to detect sulfide ions ($S^{2−}$), producing a black spot on filter paper?
What color change is observed when a soluble sulfide salt reacts with sodium nitroprusside (SNP)?
What color change is observed when a soluble sulfide salt reacts with sodium nitroprusside (SNP)?
Which of the following reactions is commonly used as a redox test for sulfide ions ($S^{2−}$)?
Which of the following reactions is commonly used as a redox test for sulfide ions ($S^{2−}$)?
What observation indicates the presence of nitrite ions ($NO_2^−$) when a solution is tested with acidified KI and starch?
What observation indicates the presence of nitrite ions ($NO_2^−$) when a solution is tested with acidified KI and starch?
In the Griess Ilosvay test for nitrite ions, what type of compound is formed?
In the Griess Ilosvay test for nitrite ions, what type of compound is formed?
A positive brown ring test indicates the presence of which anion?
A positive brown ring test indicates the presence of which anion?
What is the key step in the brown ring test that facilitates the formation of the brown ring complex?
What is the key step in the brown ring test that facilitates the formation of the brown ring complex?
Which of the following is an important reagent used in the test for chloride ($Cl^-$), bromide ($Br^-$), and iodide ($I^-$) ions?
Which of the following is an important reagent used in the test for chloride ($Cl^-$), bromide ($Br^-$), and iodide ($I^-$) ions?
What is the observation when concentrated sulfuric acid ($H_2SO_4$) is added to chloride salt?
What is the observation when concentrated sulfuric acid ($H_2SO_4$) is added to chloride salt?
What property of silver halides relates to their solubility in polar solvents?
What property of silver halides relates to their solubility in polar solvents?
Which of the following silver halides is least soluble in water?
Which of the following silver halides is least soluble in water?
Which of the following is soluble in boiling water?
Which of the following is soluble in boiling water?
Which of the following compounds will give chromyl chloride test?
Which of the following compounds will give chromyl chloride test?
What is the purpose of adding extra NaOH in chromyl chloride test?
What is the purpose of adding extra NaOH in chromyl chloride test?
In the layer test for $Br^−$ and $I^−$, what is the oxidizing agent used to liberate the halogens from their halide ions?
In the layer test for $Br^−$ and $I^−$, what is the oxidizing agent used to liberate the halogens from their halide ions?
In the layer test for $Br^⁻$ and $I^⁻$, what color would the organic layer typically be if only bromide ions were present?
In the layer test for $Br^⁻$ and $I^⁻$, what color would the organic layer typically be if only bromide ions were present?
What type of reaction is primarily involved in the confirmatory tests for sulfate ions ($SO_4^{2-}$)?
What type of reaction is primarily involved in the confirmatory tests for sulfate ions ($SO_4^{2-}$)?
Which of the following reagents is commonly used to confirm the presence of sulfate ions ($SO_4^{2−}$)?
Which of the following reagents is commonly used to confirm the presence of sulfate ions ($SO_4^{2−}$)?
According to the general rules of solubility, which of the following statements is generally true for carbonates ($CO_3^{2-}$)?
According to the general rules of solubility, which of the following statements is generally true for carbonates ($CO_3^{2-}$)?
Flashcards
Salt Analysis
Salt Analysis
Analysis involving identification of cations and anions in a mixture
Anions
Anions
Ions with a negative charge
Cations
Cations
Ions with a positive charge
Interfering Anions
Interfering Anions
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Test of Anions
Test of Anions
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Class A Anions
Class A Anions
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Confirmatory Test
Confirmatory Test
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Soda Extract
Soda Extract
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Turbidity with Lime Water
Turbidity with Lime Water
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Silver Nitrate Test
Silver Nitrate Test
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Lead Acetate Test for Sulfide
Lead Acetate Test for Sulfide
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Sodium Nitroprusside Test for Sulfide
Sodium Nitroprusside Test for Sulfide
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Brown Ring Test
Brown Ring Test
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Acid Test for Chlorides
Acid Test for Chlorides
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Test to Confirm Chloride Anions
Test to Confirm Chloride Anions
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Layer Test
Layer Test
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Barium Chloride Test
Barium Chloride Test
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Study Notes
- NEET Ultimate Crash Course 2025 covers Inorganic Chemistry with a focus on Salt Analysis
- Lecture 01 introduces Salt Analysis by Mohit Dadheech (MD Sir) for Physics Wallah
Topics Covered
- Introduction to Salt Analysis.
- Tests for Anions.
NEET Syllabus - Anions
- Includes CO₃²⁻, S²⁻, NO₂⁻, Cl⁻, Br⁻, I⁻, NO₃⁻, and SO₄²⁻
- The syllabus also covers Cations (Pb²⁺, Cu²⁺, Al³⁺, Fe³⁺, Zn²⁺, Ni²⁺, Ca²⁺, Ba²⁺, Mg²⁺, NH₄⁺)
Introduction to Salt Analysis
- Salt analysis involves detecting cations and anions from a given mixture (salt).
- Salts are formed from an acid and a base.
- The process includes dissolving the salt (MX) into its ions (M⁺ and X⁻)
Components of Salt Compounds
- Salt is derived from an acid and a base.
- Acidic radicals come from acids.
- Basic radicals come from bases.
Interfering Anions
- Anions are identified before cations during salt analysis.
- Some anions interfere with the test of cations and must be removed using suitable methods.
- Examples of interfering anions: Fluoride (F⁻), Borate (BO3³⁻), Oxalate (C₂O₄²⁻), Arsenate (AsO₄³⁻), Silicate (SiO₃²⁻), and Phosphate (PO₄³⁻)
Test of Anions
- Involves preliminary tests and confirmatory tests
Classification of Anions
- Class A: Anions that produce volatile products with acid (gas).
- Class B: Anions that do not produce volatile products with acid.
Class A Anions
- Subgroup 1: Gives volatile products with dilute H₂SO₄ or dilute HCl, including CO₃²⁻, S²⁻, NO₂⁻, SO₃²⁻, HCO₃⁻, CH₃COO⁻
- Subgroup 2: Gives volatile products with concentrated H₂SO₄, including Cl⁻, Br⁻, I⁻, NO₃⁻, F⁻, C₂O₄²⁻
Class B Anions
- Subgroup 1: By precipitation reactions, such as SO₄²⁻, PO₄³⁻
- Subgroup 2: By Redox Reactions, such as Cr₂O₇²⁻, MnO₄⁻
Preliminary Test for Class A - Subgroup 1 Anions
- Reactions with dilute HCl
- Dry salt is reacted with dilute HCl or dilute H₂SO₄.
- Colorless, odorless gas with brisk effervescence turns lime water milky, indicating CO₃²⁻ is present
- Rotten egg-like smell indicates the presence of S²⁻
Preliminary Test for Class A - Subgroup 2 Anions
- Dry salt reacts with concentrated H₂SO₄.
- Colourless pungent smell gas which gives white dense fumes with glass rod dipped into NH₄OH HCl↑
- Reddish-brown colored gas with a pungent smell. Intensity of gas increases on addition of MnO₂
- Violet Vapours; Intensity of gas increases on addition of MnO₂
- Brown gas: intensity of gas increases on addition of Cu turning and solution becomes blue
Reactions Involving Nitrogen Dioxide
- Br₂ + H₂O -> Brown colour
- NO₂ + H₂O -> colourless compounds
Identifying Volatile Products with Dilute H₂SO₄
- Na₂S produces a volatile product with dilute H₂SO₄
Practice Questions
- NaX + C.H₂SO₄ → Y (Vapors) + H₂O → Brown solution where X = Br⁻ and Y = Br₂
Acidic Radical Interference
- C₂O₄²⁻ can interfere with cation tests
Salt Reactions with C.H₂SO₄
- Dilute H₂SO₄ will react with most salts whereas C.H₂SO₄ only reacts with subgroups
Confirmatory Tests for Anions
- Performed via wet tests.
- Use the water extract directly for testing if the salt is soluble.
- If insoluble, make it soluble first.
Soda Extract Preparation
- Insoluble salts are made soluble by preparing a sodium carbonate extract (soda extract).
- Mix 1 part salt + 3 parts Na₂CO₃ + H₂O to create a solution and filter it.
- The filtrate is used as the soda extract.
Considerations for Soda Extract Preparation
- Use for water insoluble salt.
- Process creates a double decomposition reaction
- Need to neutralize soda extract solution before testing with suitable acids
- Soda extract solution has a medium basic properties, and needs to be neutralized through acid
Confirmatory Tests and Soda Extract
- Confirmatory (wet) tests are performed using a water extract if the salt is soluble in water.
- Use sodium carbonate extract if the salt is insoluble in water.
- Soda extract solution is generally not required for CO₃²⁻/HCO₃⁻
Confirmatory test for CO₃²⁻
- Dry salt and dilute H₂SO₄ produces CO₂
- Turbidity due to the formulation of CaCO₃ or BaCO₃ formation
- Pass CO₂ through lime water (Ca(OH)2) or Baryta water (Ba(OH)2). it turns milky
Test with Barium Chloride
- White precipitate (BaCO₃) forms.
- BaCl₂/CaCl₂ + HCL is added to precipitate
- Ba(NO₃)₂/Ca(NO₃)₂+HNO₃ is added to precipitate
Test with Silver Nitrate (AgNO₃)
- A pale yellow precipitate forms with AgNO₃.
- AgNO₃ with boiling turns Brown PPT
- AgNO₃ + HNO₃ turns W/I PPT
- AgNO₃ + HCL turns white PPT
- With excess NH₃ creates (Ag(NM₃)₂)+ complex
Confirmatory Tests for S²⁻ (Sulphide Ions)
- React salt with dilute HCl, releasing H₂S gas.
- Black spot on filter paper upon reaction with lead acetate filter paper
- Yellow spot on filter paper with cadmium acetate filter paper.
Reactions and Soluble Salts for sulphides
- Na₂S + Na[Fe(CN)₅NO] → Na₄[Fe(CN)₅NOS]
- H₂S reacts with lead acetate to form lead sulfide (PbS).
- H₂S reacts with cadmium acetate to form cadmium sulfide (CdS).
Additional Tests
- Ppt test
- Pb(CH₃COO)₂ -> pbs Black
- Cd(CH₃COO)₂ -> Cds yellow
- Ppt test using AgNO₃ to form black Ag₂S.
- Hg (NO₃)₂ HgS Black
Redox Test
- Using Cr₂O₇²⁻
- Using Cl₂ water
- Using MnO₄⁻
- Using Br ₂ in presence of iodide leads to reduction and a colour change from violet to colourless
Confirmatory tests for NO₂⁻ (Nitrite Ion)
- Salt dissolved in H₂SO₄ yields reddish brown gas (NO₂↑) which is then tested KI + starch which turns blue
- Sulphanilic acid + 1-Naphthylamine results in the formation of a red azo dye.
Reactions involving NO₂⁻
- NO₂⁻ + CH₃COOH -> HNO₂
- HNO₂ + KI -> I₂
- I₂ + starch = blue colour
Confirmatory Tests for Halides (Cl⁻, Br⁻, I⁻)
- Subgroup 2 anions (NO₃⁻, Cl⁻, Br⁻, I⁻) use C.H₂SO₄ as group reagent
- Acid test is used
- Silver nitrate (AgNO₃) also is used
Acid test for NO₃⁻ (Nitrate Ion)
- NO₃⁻ + H⁺ from H₂SO₄ -> HNO₃
- Cu turns into CuSO₄
- Brown fumes are released
Brown Ring Test for NO₃⁻
- Brown Ring test for NO₃⁻, C H₂SO₄ + FeSO₄ leads to [Fe(H₂O)₅NO] SO₄ in the presence of a brown ring reaction
- Reaction occurs when nitrate reacts with sulfuric acid to make nitric acid (HNO₃),
- HNO₃ work as ligand and creates brown ring.
Acid Test for Halides (Cl⁻, Br⁻, I⁻)
- Cl⁻ produces HCl with H₂SO₄.
- Br⁻ forms red bromine vapor, intensified by adding MnO₂
- MnO₂
Silver Nitrate (AgNO₃) Tests
- AgI is the least soluble in NH₃ of the silver halides. AgCl is soluble
Lead Nitrate Tests
- PbCl₂ is soluble in hot water.
- Pbl₂ is soluble in boiling water.
Special Test for Cl⁻: Chromyl Chloride Test
- Only given by ionic chlorides.
- CCl₄, HgCl₂, SnCl₂, KCl, CaCl₂, NaCl, RbCl, BaCl₂.
Chromyl Chloride Test Process
- Chlorides in the presence of potassium dichromate react to form chromyl chloride (CrO₂Cl₂),
- For removal of Extra NaOH for the test by using Pb and Na0H, this creates PbCrO₄ ( lead chromate) a yellow ppt
Oxidation Power of Halogens
- The oxidizing power of halogens is F₂ > Cl₂ > Br₂ > I₂
- The test also relies on the principle that halogens can oxidize halides of higher atomic number.
Layer Test Bromide Iodide
- The solubility increases as polar solvent increases
Soluble and Insoluble Compounds
- CO₃², So₃², All are W/1 except Except Low & NHut with Nat, kt, Rb+, Cst
- All are w/s Except NaHCO₃ the are SS
- NO3 & NO2 → All are w/s
- CH₃COO →All are w/s Except Ag/Hg2/ Cu2
- S²- sulphide > W/I Except IA & IIA and NHub
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