🔥 Activity 1.11 – Oxidation and Reduction (Redox Reaction)

 Certainly, Mayank! Here's a CBSE Class 10–aligned explanation of Activity 1.11, along with an answer to the Recall of Activity 1.1. The focus is on conceptual clarity, oxidation-reduction (redox) concepts, and exam readiness.

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🔥 Activity 1.11 – Oxidation and Reduction (Redox Reaction)

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

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🎯 Objective:

To demonstrate how a metal (copper) undergoes oxidation and how the product can be reduced using hydrogen gas.

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🧪 Materials Required:

• Copper powder (about 1 gram)

• China dish

• Heat source (burner or spirit lamp)

• Hydrogen gas (for part 2 of the reaction)

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🔬 Procedure:

1. Take a small quantity of copper powder in a china dish.

2. Heat the copper gently.

3. Observe any colour change.

4. Now, pass hydrogen gas over the heated copper oxide.

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👁️ Observations:

Step	What Happens	Chemical Equation
1. Heating copper	Surface turns black due to formation of copper(II) oxide (CuO)

$$2\text{Cu} + \text{O}_2 \xrightarrow{\text{Heat}} 2\text{CuO}$$

| 2. Passing hydrogen gas over CuO | Black coating disappears; brown copper reappears |

$$\text{CuO} + \text{H}_2 \xrightarrow{\text{Heat}} \text{Cu} + \text{H}_2\text{O}$$

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🔍 Explanation:

• In reaction (1): Copper gains oxygen to form copper(II) oxide → oxidation

• In reaction (2):

  • Copper oxide loses oxygen → reduction

  • Hydrogen gains oxygen → oxidation

✅ This type of reaction, where one substance is oxidised and the other is reduced, is called a Redox Reaction.

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🧪 Other Examples of Redox Reactions:

✅ Example 1:

$$\text{ZnO} + \text{C} \rightarrow \text{Zn} + \text{CO}$$

• Carbon is oxidised, zinc oxide is reduced

✅ Example 2:

$$\text{MnO}_2 + 4\text{HCl} \rightarrow \text{MnCl}_2 + 2\text{H}_2\text{O} + \text{Cl}_2$$

• HCl is oxidised, MnO₂ is reduced

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🧠 Recall – Activity 1.1: Magnesium Burning

What happens when a magnesium ribbon burns in air and forms magnesium oxide?

✅ Reaction:

$$2\text{Mg} + \text{O}_2 \rightarrow 2\text{MgO}$$

✅ Explanation:

• Magnesium gains oxygen during the reaction.

• Therefore, magnesium is oxidised.

• This is a redox reaction, as oxygen is involved in the change of oxidation state.

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📌 Key Concepts Summary:

Process	Definition
Oxidation	Gain of oxygen / Loss of hydrogen
Reduction	Loss of oxygen / Gain of hydrogen
Redox	Both oxidation and reduction occur together

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🧠 CBSE Exam Tip:

Q: Define oxidation and reduction. Give one redox reaction as an example.
✅ Answer:

• Oxidation: Gain of oxygen or loss of hydrogen

• Reduction: Loss of oxygen or gain of hydrogen

• Example:

$$\text{CuO} + \text{H}_2 \rightarrow \text{Cu} + \text{H}_2\text{O}$$

(CuO is reduced, H₂ is oxidised)

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Let me know if you'd like a Redox reaction flowchart, diagram worksheet, or quiz practice for your class!