What is Decomposition Reaction with Electricity? | Simple Explanation for Class 10

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What is a Decomposition Reaction with Electricity?

Grade Level:

Class 10

AI/ML, Physics, Biotechnology, Space Technology, Chemistry, Engineering, Medicine

Definition

What is it?

A decomposition reaction with electricity, also known as electrolysis, is a chemical process where a single compound breaks down into two or more simpler substances when an electric current is passed through it. It's like using electrical energy to 'un-mix' things that are chemically bonded together.

Simple Example

Quick Example

Imagine you have a glass of water. Water (H₂O) is a compound. If you pass electricity through it, the water will break down into hydrogen gas and oxygen gas. It's like how a mobile phone battery uses electricity to power the phone, but here, electricity is used to break chemical bonds.

Worked Example

Step-by-Step

Let's see how water (H₂O) can be broken down using electricity.

1. **Setup:** Take a beaker of water. Add a pinch of an acid or base (like sulfuric acid) to make it conduct electricity better. This is called an electrolyte.
---2. **Electrodes:** Dip two carbon rods (or platinum electrodes) into the water. These are called electrodes.
---3. **Power Source:** Connect the carbon rods to a battery. One rod will be connected to the positive terminal (anode) and the other to the negative terminal (cathode).
---4. **Observation at Cathode (Negative):** Bubbles of hydrogen gas (H₂) will form at the negative electrode. The reaction is: 2H⁺ + 2e⁻ → H₂.
---5. **Observation at Anode (Positive):** Bubbles of oxygen gas (O₂) will form at the positive electrode. The reaction is: 2H₂O → O₂ + 4H⁺ + 4e⁻.
---6. **Overall Reaction:** The water is decomposed into its constituent elements. The overall reaction is: 2H₂O (liquid) → 2H₂ (gas) + O₂ (gas).

**Answer:** Water is broken down into hydrogen and oxygen gases by passing electricity through it.

Why It Matters

Electrolysis is crucial in many industries, from making pure metals to producing important chemicals. Engineers use it to refine metals like aluminum, and it's vital in the production of hydrogen fuel for future energy needs, which could power cars and rockets. This process is also used in electroplating, giving a shiny, protective layer to items like jewellery or car parts.

Common Mistakes

MISTAKE: Thinking all decomposition reactions need electricity. | CORRECTION: Decomposition can also happen with heat (thermal decomposition) or light (photolytic decomposition). Electricity is just one way.

MISTAKE: Confusing electrolysis with simple melting. | CORRECTION: Melting is a physical change of state. Electrolysis is a chemical change where new substances are formed by breaking chemical bonds using electricity.

MISTAKE: Believing pure water conducts electricity well. | CORRECTION: Pure water is a poor conductor of electricity. A small amount of acid, base, or salt needs to be added to make it conductive enough for electrolysis to occur effectively.

Practice Questions

Try It Yourself

QUESTION: What is the main energy form used to break down compounds in electrolysis? | ANSWER: Electrical energy.

QUESTION: Name two gases produced when water is decomposed by electricity. | ANSWER: Hydrogen and Oxygen.

QUESTION: If you perform electrolysis on molten sodium chloride (NaCl), what products would you expect at the anode and cathode respectively? | ANSWER: At the anode (positive electrode), chlorine gas (Cl₂) would be produced. At the cathode (negative electrode), molten sodium metal (Na) would be produced.

MCQ

Quick Quiz

Which of the following is an example of a decomposition reaction with electricity?

Burning of wood

Rusting of iron

Breaking down of water into hydrogen and oxygen

Mixing salt in water

The Correct Answer Is:

Option C, the breaking down of water into hydrogen and oxygen, is a classic example of electrolysis, which uses electricity for decomposition. The other options are combustion, oxidation, and dissolution, respectively, and do not involve electrical decomposition.

Real World Connection

In the Real World

In India, electrolysis is used in industries to extract pure metals like aluminum from its ore (bauxite). It's also crucial in electroplating, where a thin layer of a valuable metal (like gold or silver) is deposited onto a cheaper metal to make jewellery or even coat car parts for protection and shine, making them look brand new like those shiny autos in Mumbai!

Key Vocabulary

Key Terms

ELECTROLYSIS: The process of decomposing a compound using electricity | ELECTROLYTE: A substance that conducts electricity when molten or dissolved in a solvent | ELECTRODES: Conductors (like metal rods) through which electricity enters or leaves an electrolyte | ANODE: The positive electrode where oxidation occurs | CATHODE: The negative electrode where reduction occurs

What's Next

What to Learn Next

Now that you understand decomposition by electricity, you can explore other types of decomposition reactions, such as thermal decomposition (using heat) and photolytic decomposition (using light). Understanding these will give you a complete picture of how compounds can break down.