double displacement 3

 Certainly, Mayank! Here's a clear, CBSE Class 10–level explanation of Activity 1.10, followed by answers to the Recall Activity 1.2, all framed in a structured, exam-friendly and conceptually strong manner.

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🧪 Activity 1.10 – Double Displacement & Precipitation Reaction

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

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🎯 Objective:

To demonstrate the formation of a precipitate through a double displacement reaction.

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🔬 Materials Required:

• Sodium sulphate solution (Na₂SO₄)

• Barium chloride solution (BaCl₂)

• 2 test tubes

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🔍 Procedure:

1. Take 3 mL of Na₂SO₄ solution in one test tube.

2. Take 3 mL of BaCl₂ solution in another test tube.

3. Mix the two solutions together.

4. Observe the changes.

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👁️ Observation:

• A white, insoluble solid is formed.

• This solid is a precipitate of barium sulphate (BaSO₄).

• Sodium chloride (NaCl) remains dissolved in the solution.

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🧪 Balanced Chemical Equation:

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

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📌 Explanation:

• SO₄²⁻ (from Na₂SO₄) combines with Ba²⁺ (from BaCl₂) to form BaSO₄, which is insoluble in water.

• This type of reaction is a precipitation reaction — a solid product forms from the mixing of two solutions.

• Since ions are exchanged between two ionic compounds, this is also a double displacement reaction.

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🔁 Recall Activity 1.2 – Reaction Between Lead Nitrate and Potassium Iodide

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🧪 Reaction:

$$\text{Pb(NO}_3)_2 (aq) + 2\text{KI} (aq) \rightarrow \text{PbI}_2 (s) ↓ + 2\text{KNO}_3 (aq)$$

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✅ Answers:

1. Colour of the precipitate:

   • Yellow

2. Name of the compound precipitated:

   • Lead(II) iodide (PbI₂)

3. Is it a double displacement reaction?

   • Yes, because there is an exchange of ions:

     • Pb²⁺ from Pb(NO₃)₂ reacts with I⁻ from KI to form PbI₂

     • K⁺ and NO₃⁻ form KNO₃

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📘 Exam Tip:

In questions involving precipitation reactions, always:

• Write the balanced chemical equation

• Mention the colour and name of the precipitate

• Classify it as a double displacement reaction

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🧠 Key Takeaway:

• Any reaction in which two compounds exchange ions and form a precipitate is called a double displacement (precipitation) reaction.

• These are very common in salt analysis and water purification.

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Let me know if you want this as a lab worksheet, quiz format, or diagram-based board slide for class use!