🔁 Displacement and Double Displacement Reactions

 Certainly, Mayank! Here's a CBSE Class 10–focused explanation of both Displacement and Double Displacement Reactions, written in a crisp and concept-based format — ideal for class notes, presentations, or revision worksheets.

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🔁 Displacement and Double Displacement Reactions

(Class 10 Science – Chapter 1: Chemical Reactions and Equations)

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🔹 1. Displacement Reaction

🎯 Definition:

A displacement reaction occurs when a more reactive element displaces a less reactive element from its compound.

✅ Always involves a single element and a compound.

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🧪 General Form:

$$A + BC \rightarrow AC + B$$

✅ Where A is more reactive than B.

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📘 Examples:

✅ Zinc displaces copper:

$$\text{Zn} + \text{CuSO}_4 \rightarrow \text{ZnSO}_4 + \text{Cu}$$

• Zinc (more reactive) displaces copper from copper sulfate solution.

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✅ Iron displaces copper:

$$\text{Fe} + \text{CuSO}_4 \rightarrow \text{FeSO}_4 + \text{Cu}$$

• Iron replaces copper due to higher reactivity.

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🔍 Key Characteristics:

• Involves reactivity series of metals.

• Occurs in aqueous solution.

• Used in metal extraction and electroplating.

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🔄 2. Double Displacement Reaction

🎯 Definition:

A double displacement reaction is a chemical reaction in which two compounds exchange ions to form two new compounds.

✅ Often leads to the formation of a precipitate, gas, or neutral compound.

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🧪 General Form:

$$AB + CD \rightarrow AD + CB$$

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📘 Examples:

✅ Precipitation Reaction:

$$\text{BaCl}_2 (aq) + \text{Na}_2\text{SO}_4 (aq) \rightarrow \text{BaSO}_4 (s) ↓ + 2\text{NaCl} (aq)$$

• White precipitate of barium sulfate (BaSO₄) is formed.

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✅ Neutralization Reaction (Acid + Base):

$$\text{NaOH} (aq) + \text{HCl} (aq) \rightarrow \text{NaCl} (aq) + \text{H}_2\text{O} (l)$$

• Sodium hydroxide and hydrochloric acid react to form salt and water.

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🔍 Key Characteristics:

• Involves ionic exchange.

• At least one product is insoluble or stable (precipitate, gas, or water).

• Includes neutralization and precipitation reactions.

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📚 Quick Comparison Table:

Feature	Displacement Reaction	Double Displacement Reaction
Reactants	Element + Compound	Compound + Compound
What happens	More reactive element displaces another	Exchange of ions between two compounds
Reactivity series	Required	Not required
Example	Zn + CuSO₄ → ZnSO₄ + Cu	BaCl₂ + Na₂SO₄ → BaSO₄ ↓ + 2NaCl
Product formed	One element + one compound	Two new compounds (often with precipitate)

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🧠 CBSE Exam Tip:

Q: Identify the type of reaction:

$$\text{AgNO}_3 + \text{NaCl} \rightarrow \text{AgCl} ↓ + \text{NaNO}_3$$

✅ Answer: Double displacement reaction → Forms white precipitate (AgCl)

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🎤 Final Thought for Students:

“In chemistry, some elements take charge and push others out — while others just swap partners in a graceful exchange!”

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