Mendius Reaction and Gattermann Reaction

Mendius reaction and Gattermann reaction are important named reactions of organic chemistry. These reactions are commonly studied in Class 12, NEET, and JEE syllabi. Both reactions are used for the preparation of important organic compounds.

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1. Mendius Reaction

Mendius reaction is the reduction of nitriles to primary amines using sodium metal in alcohol. It is an important method for the preparation of aliphatic primary amines.

General Reaction

R–C≡N + 4[H] → R–CH₂–NH₂

Reagents Used

• Sodium metal (Na)
• Alcohol (ethanol or methanol)

Example

CH₃–CN + Na / C₂H₅OH → CH₃–CH₂–NH₂

Important Points

• Nitrile group is reduced to primary amine
• Carbon chain length increases by one carbon atom
• Sodium acts as a reducing agent
• Reaction proceeds through nascent hydrogen

Uses

• Preparation of primary aliphatic amines
• Used in organic synthesis

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2. Gattermann Reaction

Gattermann reaction is used for the introduction of aldehyde group into an aromatic ring. It is also known as a formylation reaction of aromatic compounds.

General Reaction

Ar–H + HCN + HCl → Ar–CHO

Catalysts Used

• Anhydrous aluminium chloride (AlCl₃)
• Cuprous chloride (CuCl)

Example

C₆H₆ + HCN + HCl → C₆H₅–CHO

In this reaction, benzene is converted into benzaldehyde.

Important Points

• Aldehyde (–CHO) group is introduced into aromatic ring
• Reaction mainly occurs at ortho and para positions
• Used for preparation of aromatic aldehydes

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Difference Between Gattermann and Gattermann–Koch Reaction

Gattermann Reaction	Gattermann–Koch Reaction
Uses HCN and HCl	Uses CO and HCl
Uses AlCl3 and CuCl as catalyst	Uses AlCl3 and CuCl as catalyst
Less commonly used	More commonly used

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One-Line Examination Answers

Mendius Reaction: Reduction of nitriles to primary amines using sodium metal in alcohol.

Gattermann Reaction: Formylation of aromatic compounds using HCN and HCl in presence of AlCl₃ and CuCl.

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Prepared for academic and examination purposes.

Reactions in Which Sodium Mercury Amalgam is Used

Reactions in Which Sodium–Mercury Amalgam (Na–Hg) is Used

Sodium–mercury amalgam, written as Na–Hg, is an important reagent used in both organic and inorganic chemistry. It mainly acts as a mild and controlled reducing agent. Because of its gentle action, it is preferred over metallic sodium in many reactions.

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What is Sodium–Mercury Amalgam?

Sodium amalgam is a solution of sodium metal in mercury. Mercury controls the high reactivity of sodium and allows the gradual release of electrons or nascent hydrogen.

Due to this property, sodium amalgam is widely used in laboratory reductions.

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1. Reduction of Aldehydes

Sodium amalgam reduces aldehydes to primary alcohols in aqueous or alcoholic medium.

General Reaction:

R–CHO + [H] → R–CH₂OH

Here, sodium amalgam acts as a source of nascent hydrogen.

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2. Reduction of Ketones

Ketones are reduced to secondary alcohols using sodium amalgam.

General Reaction:

R–CO–R′ + [H] → R–CHOH–R′

This reaction is useful when mild reduction conditions are required.

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3. Reduction of Nitro Compounds

Nitro compounds are reduced to amines using sodium amalgam.

General Reaction:

R–NO₂ + Na–Hg + H₂O → R–NH₂

This reaction is preferred when strong reducing agents like tin and hydrochloric acid are not suitable.

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4. Reduction of Unsaturated Compounds

Alkenes and alkynes can be reduced by sodium amalgam under controlled conditions.

Example:

R–CH=CH–R → R–CH₂–CH₂–R

The hydrogen produced from sodium amalgam adds across the multiple bond.

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5. Reduction of Oximes and Imines

Oximes and imines are reduced to corresponding amines.

Example:

R–CH=NOH + Na–Hg → R–CH₂–NH₂

This reaction is important in organic synthesis.

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6. Reduction of Carbonyl Compounds in Aqueous Medium

Sodium amalgam reduces carbonyl compounds such as aldehydes and ketones in aqueous medium without affecting sensitive functional groups.

Hence, it is useful for selective reduction reactions.

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7. Reduction of Metal Ions (Inorganic Chemistry)

Sodium amalgam is also used to reduce metal ions in solution.

Example:

Fe³⁺ + Na–Hg → Fe²⁺

This reaction is commonly used in redox chemistry experiments.

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8. Preparation of Alcohols from Acyl Chlorides

Acyl chlorides can be reduced to primary alcohols using sodium amalgam.

General Reaction:

R–COCl + Na–Hg + H₂O → R–CH₂OH

This method avoids harsh reducing conditions.

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Why Sodium–Mercury Amalgam is Preferred

• It is safer than metallic sodium
• It provides controlled reduction
• It is a mild reducing agent
• It is suitable for selective reactions

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One-Line Examination Answer

Sodium–mercury amalgam is used as a mild reducing agent in reactions such as reduction of aldehydes, ketones, nitro compounds, oximes, imines, and metal ions.

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Educational content prepared for chemistry students.

Why Chemical Equation is Used to Find Molecularity and Strength of KMnO4

Why Chemical Equation is Used to Find Molecularity and Strength of KMnO₄ Using M/20 Mohr’s Salt Solution

In volumetric analysis, especially in Class 11 and Class 12 chemistry practicals, potassium permanganate (KMnO₄) is commonly standardized using M/20 Mohr’s salt solution. A very common question asked in exams is:

“Why is a chemical equation required to find the molecularity and strength of KMnO₄?”

The answer lies in the stoichiometry of the reaction and the nature of KMnO₄.

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1. Importance of Chemical Equation in Volumetric Analysis

In titration calculations, we do not depend only on the volume of solutions. All calculations are based on the balanced chemical equation.

KMnO₄ does not react with Mohr’s salt in a simple 1:1 ratio. Therefore, without a chemical equation:

• The reaction ratio cannot be known
• The number of electrons transferred cannot be determined
• The equivalent weight and n-factor cannot be calculated

Hence, a chemical equation is compulsory to calculate the molecularity and strength of KMnO₄.

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2. Why Mohr’s Salt is Used

Mohr’s salt (FeSO₄·(NH₄)₂SO₄·6H₂O) is used because:

• It is a primary standard
• It has high purity
• It has stable composition
• Its molarity (M/20) is accurately known

KMnO₄ is not a primary standard because it decomposes on standing and may contain impurities. Therefore, KMnO₄ solution must be standardized using Mohr’s salt.

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3. Chemical Equation of the Reaction

The titration is carried out in acidic medium using dilute sulphuric acid. The balanced ionic equation is:

MnO₄⁻ + 5Fe²⁺ + 8H⁺ → Mn²⁺ + 5Fe³⁺ + 4H₂O

From the above equation, we observe that:

• 1 mole of KMnO₄ reacts with 5 moles of Fe²⁺
• KMnO₄ acts as an oxidizing agent
• Mohr’s salt acts as a reducing agent

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4. Determination of Molecularity (Molarity / Normality)

From the chemical equation, it is clear that one mole of KMnO₄ gains five electrons. Therefore:

n-factor of KMnO₄ = 5

Using the titration formula:

N₁V₁ = N₂V₂

The normality of Mohr’s salt is known, and the volumes are measured experimentally. Using this equation, the normality of KMnO₄ is calculated.

Molarity of KMnO₄ is then obtained using:

M = N / n-factor

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5. Determination of Strength of KMnO₄

Once the molarity of KMnO₄ is known, its strength is calculated by:

Strength (g/L) = Molarity × Molar Mass

Molar mass of KMnO₄ = 158 g mol⁻¹

Thus, the strength of KMnO₄ solution can be accurately determined.

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6. Why Chemical Equation is Essential (Exam Point)

• To know the exact reaction ratio
• To calculate the n-factor of KMnO₄
• To determine molarity and strength correctly
• Because the reaction is not 1:1

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7. One-Line Board Answer

Chemical equation is used because KMnO₄ reacts with Mohr’s salt in a fixed stoichiometric ratio, which is necessary to calculate the molecularity and strength of KMnO₄.

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Prepared for educational and examination purposes.

Named Reactions of Class XI and XII Organic Chemistry

Named reactions are very important in organic chemistry. These reactions are frequently asked in CBSE board exams, NEET, JEE, and other competitive examinations. This article provides a complete chapter-wise list of important named reactions from Class XI and Class XII organic chemistry.

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CLASS XI – ORGANIC CHEMISTRY

1. General Organic Chemistry (GOC)

• Wurtz Reaction
• Fittig Reaction
• Wurtz–Fittig Reaction
• Kolbe’s Electrolytic Reaction
• Frankland Reaction

2. Alkanes

• Wurtz Reaction
• Kolbe’s Electrolysis
• Frankland Reaction
• Hunsdiecker Reaction
• Hofmann Degradation

3. Alkenes

• Dehydration of Alcohols
• Saytzeff (Zaitsev) Rule
• Hoffmann Rule
• Markovnikov’s Rule
• Anti-Markovnikov Addition (Peroxide Effect / Kharasch Effect)
• Baeyer’s Test
• Ozonolysis

4. Alkynes

• Ozonolysis of Alkynes
• Acidic Nature of Terminal Alkynes
• Polymerisation Reactions

5. Aromatic Hydrocarbons

• Friedel–Crafts Alkylation
• Friedel–Crafts Acylation
• Wurtz–Fittig Reaction
• Nitration Reaction
• Sulphonation Reaction
• Halogenation Reaction

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CLASS XII – ORGANIC CHEMISTRY

6. Haloalkanes and Haloarenes

• Wurtz Reaction
• Fittig Reaction
• Wurtz–Fittig Reaction
• Finkelstein Reaction
• Swarts Reaction
• Sandmeyer Reaction
• Gattermann Reaction
• Hunsdiecker Reaction
• Dow’s Process
• Ullmann Reaction

7. Alcohols, Phenols and Ethers

• Williamson Ether Synthesis
• Reimer–Tiemann Reaction
• Kolbe–Schmitt Reaction
• Dehydration of Alcohols
• Lucas Test
• Esterification Reaction

8. Aldehydes and Ketones

• Aldol Condensation
• Cross Aldol Condensation
• Cannizzaro Reaction
• Clemmensen Reduction
• Wolff–Kishner Reduction
• Rosenmund Reduction
• Stephen Reaction
• Haloform Reaction
• Perkin Reaction
• Benzoin Condensation

9. Carboxylic Acids

• Hell–Volhard–Zelinsky (HVZ) Reaction
• Esterification Reaction
• Decarboxylation Reaction
• Kolbe’s Electrolytic Reaction
• Reduction to Alcohol using LiAlH₄

10. Amines

• Hofmann Bromamide Reaction
• Gabriel Phthalimide Synthesis
• Carbylamine Reaction
• Hinsberg Test
• Diazotisation Reaction
• Sandmeyer Reaction
• Gattermann Reaction
• Coupling Reaction (Azo Dye Formation)

11. Biomolecules

• Peptide Bond Formation
• Hydrolysis of Proteins
• Mutarotation
• Fermentation Reaction
• Glycosidic Bond Formation

12. Polymers

• Addition Polymerisation
• Condensation Polymerisation
• Free Radical Polymerisation
• Ziegler–Natta Polymerisation

13. Chemistry in Everyday Life

This chapter mainly focuses on applications of chemistry. Very few named reactions are directly asked from this chapter.

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Most Important Exam-Oriented Named Reactions

• Wurtz Reaction
• Kolbe’s Electrolysis
• Friedel–Crafts Reaction
• Markovnikov’s Rule
• Anti-Markovnikov Addition
• Aldol Condensation
• Cannizzaro Reaction
• Clemmensen Reduction
• Wolff–Kishner Reduction
• HVZ Reaction
• Reimer–Tiemann Reaction
• Kolbe–Schmitt Reaction
• Sandmeyer Reaction
• Hofmann Bromamide Reaction
• Gabriel Synthesis
• Williamson Ether Synthesis

Conclusion: Learning named reactions helps students quickly identify reaction pathways, reagents, and products. Proper revision of these reactions can significantly improve performance in board exams and competitive examinations.

How to Find Cation and Anion in a Given Salt

In qualitative inorganic analysis, the identification of a salt involves determining two components:

• Cation (Basic radical)
• Anion (Acid radical)

This systematic analysis is commonly followed in CBSE and other board practical chemistry laboratories. The identification is carried out step by step using preliminary tests, dry tests, and wet confirmatory tests.

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Step 1: Preliminary Examination (Dry Tests)

(a) Physical Observation

Colour of the salt:

• Blue colour – Copper (Cu²⁺)
• Green colour – Iron (Fe²⁺) or Nickel (Ni²⁺)
• White colour – Zinc (Zn²⁺), Calcium (Ca²⁺), Sodium (Na⁺), Potassium (K⁺)

Smell of the salt:

• Ammonia smell – Ammonium ion (NH₄⁺)
• Rotten egg smell on heating – Sulphide ion (S²⁻)

(b) Action of Heat

Heat a small amount of the salt in a dry test tube and observe:

• Crackling sound – Presence of water of crystallization
• Evolution of gas:
  • Carbon dioxide – Carbonate (CO₃²⁻)
  • Sulphur dioxide – Sulphite (SO₃²⁻)
  • Brown fumes – Nitrate (NO₃⁻)

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Step 2: Solubility Test

The salt is tested for solubility in:

• Cold water
• Hot water
• Dilute hydrochloric acid (HCl)
• Dilute nitric acid (HNO₃)

This helps in selecting suitable reagents for further analysis.

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Step 3: Identification of Anion (Acid Radical)

(A) Test with Dilute Hydrochloric Acid

Add dilute HCl to the salt solution and observe:

Observation	Inference (Anion)
Effervescence; CO2 turns lime water milky	Carbonate (CO32−)
Rotten egg smell	Sulphide (S2−)
Pungent smelling gas (SO2)	Sulphite (SO32−)
No reaction	Proceed to next test

(B) Test with Concentrated Sulphuric Acid

Add concentrated H₂SO₄ to solid salt:

Observation	Anion
Brown fumes	Nitrate (NO3−)
White fumes with pungent smell	Chloride (Cl−)
Red vapours	Bromide (Br−)
Violet vapours	Iodide (I−)

(C) Confirmatory Tests for Anions

• Chloride ion: Add AgNO₃ solution → White precipitate soluble in NH₄OH
• Sulphate ion: Add BaCl₂ solution → White precipitate insoluble in HCl
• Nitrate ion: Brown ring test confirms nitrate

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Step 4: Identification of Cation (Basic Radical)

Cations are identified by systematic group analysis using specific reagents.

Group 0: Ammonium Ion

• Warm salt with NaOH → Ammonia gas evolved (Turns red litmus blue)

Group I: Silver, Lead, Mercurous Ions

• Add dilute HCl → White precipitate formed

Group II: Copper, Cadmium, Bismuth etc.

• Pass H₂S gas in acidic medium → Coloured precipitate

Group III: Iron, Aluminium, Chromium

• Add NH₄OH in presence of NH₄Cl → Precipitate formed

Group IV: Zinc, Manganese, Nickel, Cobalt

• Pass H₂S gas in basic medium → Precipitate formed

Group V: Calcium, Barium, Strontium

• Add (NH₄)₂CO₃ → White precipitate

Group VI: Sodium, Potassium, Magnesium

• Identified using flame test and special tests

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Step 5: Flame Test

Flame Colour	Cation
Golden yellow	Sodium (Na+)
Lilac	Potassium (K+)
Brick red	Calcium (Ca2+)
Apple green	Barium (Ba2+)
Blue-green	Copper (Cu2+)

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Final Result

After performing all tests and confirmatory reactions, the salt is reported as:

Cation present: __________
Anion present: __________

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Important Practical Tips

• Always identify the anion before the cation
• Write observation and inference clearly
• Confirm results using confirmatory tests
• Flame test is very useful for Group VI cations

This method ensures accurate identification of cations and anions in an unknown salt during qualitative inorganic analysis.

Clemmensen Reaction: Definition, History, Mechanism, Examples and Applications

The Clemmensen reaction is one of the most important named reactions in organic chemistry. It is widely studied at the Class 12 level, competitive examinations such as JEE and NEET, and also used in advanced organic synthesis. This reaction deals with the reduction of carbonyl compounds such as aldehydes and ketones into hydrocarbons.

Understanding the Clemmensen reaction is essential because it helps students learn how functional groups can be selectively removed under specific reaction conditions. This article explains the Clemmensen reaction in a simple, readable, and exam-oriented manner, including its history, reaction conditions, mechanism, advantages, limitations, and applications.

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What is the Clemmensen Reaction?

The Clemmensen reaction is a chemical reaction in which aldehydes or ketones are reduced to hydrocarbons using zinc amalgam (Zn–Hg) and concentrated hydrochloric acid (HCl). In this reaction, the carbonyl group (C=O) is completely removed and replaced by hydrogen atoms.

In simple words, the Clemmensen reaction converts:

Aldehyde → Alkane
Ketone → Alkane

This reaction is carried out in a strongly acidic medium, which is an important point from the examination perspective.

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General Reaction

The general form of the Clemmensen reaction is shown below using simple symbols:

R–CO–R′   +   Zn(Hg) / conc. HCl   →   R–CH₂–R′

For aldehydes:

R–CHO   →   R–CH₃

Here, R and R′ represent alkyl or aryl groups.

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Examples of Clemmensen Reaction

Example 1: Reduction of Acetone

Acetone is a simple ketone. When acetone is treated with zinc amalgam and concentrated hydrochloric acid, it is reduced to propane.

CH₃–CO–CH₃   →   CH₃–CH₂–CH₃

Example 2: Reduction of Benzaldehyde

Benzaldehyde is an aromatic aldehyde. On treatment with Clemmensen reagents, it is converted into toluene.

C₆H₅–CHO   →   C₆H₅–CH₃

This example is very important in aromatic chemistry and is frequently asked in examinations.

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Reagents Used in Clemmensen Reaction

1. Zinc Amalgam (Zn–Hg)

Zinc amalgam is prepared by treating zinc metal with mercury. The presence of mercury increases the surface activity of zinc and makes it a more effective reducing agent.

2. Concentrated Hydrochloric Acid (HCl)

Hydrochloric acid provides a strongly acidic medium, which is necessary for the Clemmensen reaction to proceed.

The reaction does not occur in neutral or basic conditions.

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History of the Clemmensen Reaction

The Clemmensen reaction was discovered in the year 1913. It was developed by a Danish chemist named Erik Christian Clemmensen.

Clemmensen was studying the reduction of carbonyl compounds under acidic conditions and found that zinc amalgam in the presence of concentrated hydrochloric acid could effectively remove the oxygen atom from aldehydes and ketones.

His work was significant because most reduction reactions at that time required either high temperatures or harsh conditions. The Clemmensen reaction provided a relatively simple and efficient method for converting carbonyl compounds into hydrocarbons.

In honor of his contribution to organic chemistry, this reaction was named the Clemmensen Reaction. Today, it is counted among the classic named reactions of organic chemistry.

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Mechanism of the Clemmensen Reaction

The exact mechanism of the Clemmensen reaction is complex and still a subject of discussion. However, it is generally believed to occur on the surface of zinc metal.

The carbonyl group gets adsorbed on the zinc surface, and electrons from zinc reduce the carbonyl carbon. Protons from hydrochloric acid supply hydrogen atoms, eventually converting the C=O group into a –CH₂– group.

For examination purposes, students are not usually required to write the detailed mechanism, but they should understand that the reaction involves electron transfer and protonation steps in an acidic medium.

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Important Characteristics of Clemmensen Reaction

• The reaction is carried out in a strongly acidic medium.
• It removes the carbonyl oxygen completely.
• It is suitable for aldehydes and ketones that are stable in acid.
• It is commonly used for aromatic ketones.

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Limitations of the Clemmensen Reaction

Despite its usefulness, the Clemmensen reaction has some limitations.

• It cannot be used for compounds that are unstable in acidic conditions.
• Functional groups such as –OH, –NH₂, and acid-sensitive groups may get destroyed.
• It is not suitable for molecules containing acid-labile substituents.

Because of these limitations, an alternative reaction is often used.

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Comparison with Wolff–Kishner Reaction

The Clemmensen reaction is often compared with the Wolff–Kishner reaction. Both reactions convert aldehydes and ketones into hydrocarbons, but the reaction conditions are different.

Clemmensen Reaction	Wolff–Kishner Reaction
Acidic medium	Basic medium
Zn–Hg / HCl	NH2NH2 / KOH
Used for acid-stable compounds	Used for base-stable compounds

This comparison is very important from the examination point of view.

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Applications of the Clemmensen Reaction

The Clemmensen reaction has many applications in organic chemistry and industrial synthesis.

• Preparation of alkanes from aldehydes and ketones.
• Synthesis of aromatic hydrocarbons.
• Used in pharmaceutical and petrochemical industries.
• Helpful in multi-step organic synthesis.

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Importance in Examinations

The Clemmensen reaction is frequently asked in:

• CBSE Class 12 board examinations
• JEE Main and JEE Advanced
• NEET
• Undergraduate chemistry courses

Students should remember the reagents, reaction conditions, and comparison with the Wolff–Kishner reaction.

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Conclusion

The Clemmensen reaction is a classic and powerful reduction reaction in organic chemistry. It allows the conversion of aldehydes and ketones into hydrocarbons using zinc amalgam and hydrochloric acid.

Its discovery by Erik Christian Clemmensen marked an important milestone in the development of organic synthesis. Despite some limitations, it remains a valuable reaction for both academic study and industrial applications.

A clear understanding of the Clemmensen reaction helps students build strong fundamentals in organic chemistry and prepares them well for competitive examinations.

All reactions of Oxalic acid

Reactions of Oxalic Acid (H₂C₂O₄) with Specific Reagents

Oxalic acid is an important organic acid studied in Class 11 and 12 Chemistry. It is a dibasic carboxylic acid and shows acidic as well as reducing properties. In this article, we will study all the important reactions of oxalic acid with specific reagents, which are frequently asked in CBSE board exams, practical exams, and competitive exams.

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1. Reaction with Alkalis (Neutralization Reaction)

Oxalic acid reacts with alkalis like sodium hydroxide to form acid salt and normal salt. Since oxalic acid is dibasic, the reaction occurs in two steps.

(a) With Sodium Hydroxide (NaOH)

Step 1 (Formation of Acid Salt):

H₂C₂O₄ + NaOH → NaHC₂O₄ + H₂O

Step 2 (Formation of Normal Salt):

NaHC₂O₄ + NaOH → Na₂C₂O₄ + H₂O

This reaction proves the dibasic nature of oxalic acid.

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2. Reaction with Carbonates and Bicarbonates

(a) With Sodium Carbonate (Na₂CO₃)

H₂C₂O₄ + Na₂CO₃ → Na₂C₂O₄ + CO₂ ↑ + H₂O

Carbon dioxide gas is evolved with brisk effervescence.

(b) With Sodium Bicarbonate (NaHCO₃)

H₂C₂O₄ + 2NaHCO₃ → Na₂C₂O₄ + 2CO₂ ↑ + 2H₂O

This reaction confirms the acidic nature of oxalic acid.

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3. Reaction with Calcium Chloride (Confirmatory Test)

Oxalic acid reacts with calcium chloride solution to form a white precipitate.

H₂C₂O₄ + CaCl₂ → CaC₂O₄ ↓ + 2HCl

The white precipitate of calcium oxalate is insoluble in water. This reaction is used as a confirmatory test for oxalic acid.

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4. Reaction with Potassium Permanganate (KMnO₄)

In acidic medium, oxalic acid acts as a strong reducing agent and decolourises potassium permanganate solution.

2KMnO₄ + 5H₂C₂O₄ + 3H₂SO₄ → K₂SO₄ + 2MnSO₄ + 10CO₂ ↑ + 8H₂O

The purple colour of KMnO₄ disappears. The reaction is slow at room temperature and becomes fast on heating.

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5. Reaction with Concentrated Sulphuric Acid

When oxalic acid is heated with concentrated sulphuric acid, it decomposes to give carbon monoxide and carbon dioxide.

H₂C₂O₄ → CO + CO₂ + H₂O

Carbon monoxide burns with a blue flame. This reaction shows the reducing nature of oxalic acid.

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6. Reaction with Alcohols (Esterification)

Oxalic acid reacts with alcohols in the presence of concentrated sulphuric acid to form esters.

With Ethanol

H₂C₂O₄ + 2C₂H₅OH → (COOC₂H₅)₂ + 2H₂O

The product formed is diethyl oxalate, which has a pleasant fruity smell.

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7. Reaction with Metals

Oxalic acid reacts with active metals like zinc to liberate hydrogen gas.

H₂C₂O₄ + Zn → ZnC₂O₄ + H₂ ↑

This reaction confirms the acidic nature of oxalic acid.

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8. Reaction with Ammonia

Oxalic acid reacts with ammonia to form ammonium oxalate.

H₂C₂O₄ + 2NH₃ → (NH₄)₂C₂O₄

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9. Thermal Decomposition

On strong heating, oxalic acid decomposes into carbon monoxide, carbon dioxide and water.

H₂C₂O₄ → CO + CO₂ + H₂O

This reaction again shows the reducing nature of oxalic acid.

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10. Reaction with Ferric Ions (Fe³⁺)

Oxalic acid reduces ferric ions to ferrous ions.

2Fe³⁺ + H₂C₂O₄ → 2Fe²⁺ + 2CO₂ + 2H⁺

This reaction is important in redox chemistry.

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Conclusion

Oxalic acid shows a wide range of reactions due to its acidic and reducing properties. The reactions with calcium chloride and potassium permanganate are especially important for practical and board examinations. A proper understanding of these reactions helps students score well in both theory and practical chemistry.

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