Best Chemical Effects of Electric Current Class 8 Notes

Chemical Effects of Electric Current Class 8 Notes

Introduction

In the previous year, we read about the Heating Effects of Electric Currents. We also read about the Magnetic Effect of Electric Current.

In this current year, we will read about the Chemical Effects of Electric Current.

Let us look at the best Chemical Effects of Electric Current Class 8 Notes.

Important topics to be discussed:

Electric Current
Good Conductors and Poor Conductors
Charge carriers- Ions
Do Liquids Conduct
Chemical Effects of Electric Current
Electroplating
Applications of Electroplating

Chemical Effects of Electric Current

What are the Chemical Effects of Electric Current

We can see the following effects depending on the nature of the solution and electrodes used-

metallic deposits on the electrodes
change in the color of the solution
a release of gas or production of bubbles in the solution

Note: To see the process of chemical effects the liquid (electrolyte) used must conduct electricity.

Important Definitions

Electric Current

It is the flow of electric charges through a conductor is electric current or it is the rate of flow of electric charges.

Electric Charges

Electrical charges are the sub-atomic particles of an atom. Electrons, protons, and neutrons are sub-atomic particles.
The electron carries negative charges, the proton carries positive charges whereas the neutron is neutral i.e., has no charge.
Like or the same charges repel each other (positive-positive or negative-negative)
Unlike or opposite charges attract each other (positive-negative)

Electric Circuit

a closed loop or path made up of electric components like wire, switch, battery, bulb, etc.

Conductors

Conductors are the materials that allow electricity to pass through them. Ex- Metals, etc

Insulators

Materials that do not allow the electric current to pass through them.

Insulators are bad or poor conductors of electricity. Ex- Wood, Plastics, Paper, etc.

Electrolyte

The liquids that allow the electric current to pass through it and it itself break into ions (charged particles)

Electrode

are the conductors that allow electricity to pass to non-metals Or poor conductors.

Anode

A positively charged electrode is called an Anode.

Cathode

A negatively charged electrode is called a cathode.

Ions

These are the charge carriers. When an atom loses or gains electrons, gains a positive or negative charge. Ex – Na+, Cl-, Ca2+ etc

Anion

negatively charged ions. Ex- Cl-

Cation

positively charged ions. Ex- Na+

Electrolysis

It is the process in which a compound breaks into its components by passing an electric current through it.

Do Liquids conduct electricity?

Yes, some liquids can conduct electricity, while others cannot. Whether a liquid conducts electricity or not depends on whether it contains charged particles, specifically ions, that can carry electric current.

Distilled water does not conduct electricity because they do not have dissolved salt ions in it, whereas tap water which has salts and minerals conducts electricity.
The solution of acids (containing H+ ions) and bases (OH- ions) will also conduct electricity.

How do liquids conduct electricity?

When different substances are mixed in water and electricity is passed through them, they break into ions (positive and negative ions) in the water. The more the ion in the liquid, the better the liquid is a conductor.

Distilled water is a poor conductor of electricity but when salt is added it conducts electricity.

Applications of Electrolysis

Electroplating
Purification of metals
Extraction of Metals from its ore

Electroplating

It is the process by which a layer of metal is deposited over another metal with the help of an electric current.
Metals that are usually used for electroplating are gold, silver, zinc, etc

Why electroplating is done?

The electroplating is done for the following reasons for electroplating-

to protect the parent metal
it is cost-efficient
It protects the parent metal from corrosion
Durability- increases the life span of the metal

Galvanization– When the coating of zinc is done on iron metals to protect them from rusting is called Galvanization.

How Electroplating is done?

The process of electroplating is based on the principle of the chemical effects of electric current.

Two electrodes of different metals should be used.
The metal on which coating is to be done should be made cathode while the metal to be deposited should be made anode.
The electrolyte should be a solution of the metal to be coated.
Example- The coating of zinc over a copper plate.

The copper plate is used as a cathode and the zinc plate as an anode, and the zinc sulphate is used as an electrolyte.

Electroplating of Zinc onto Copper

Electrolyte: Zinc sulfate solution (ZnSO4)

Anode (Positive Electrode): Zinc (Zn) electrode

Cathode (Negative Electrode): Copper (Cu) object to be plated

Balanced Equation:

At the anode (oxidation): Zn(s) → Zn²⁺(aq) + 2e⁻

At the cathode (reduction): Zn²⁺(aq) + 2e⁻ → Zn(s)

Overall Electroplating Reaction: Zn²⁺(aq) + Cu(s) → Zn(s) + Cu²⁺(aq)

In this process, zinc ions (Zn²⁺) from the zinc electrode are reduced at the cathode (copper object), forming a layer of zinc on the copper’s surface. This electroplated layer of zinc provides protection against corrosion and can also improve the appearance of the copper object.

Electroplating of Copper onto a Nickel Surface

In this example, we will electroplate copper onto a nickel surface.

Electrolyte: Copper(II) sulfate solution (CuSO4)

Anode (Positive Electrode): Copper (Cu) electrode

Cathode (Negative Electrode): Nickel (Ni) object to be plated

Balanced Equation:

At the anode (oxidation): Cu(s) → Cu²⁺(aq) + 2e⁻

At the cathode (reduction): Cu²⁺(aq) + 2e⁻ → Cu(s)

Overall Electroplating Reaction: Cu²⁺(aq) + Ni(s) → Cu(s) + Ni²⁺(aq)

In this process, copper ions (Cu²⁺) from the copper electrode are reduced at the cathode (nickel object), forming a layer of copper on the nickel surface.

Electroplating of Silver onto a Spoon (Using Silver Nitrate)

In this example, we will electroplate a spoon with a layer of silver using silver nitrate as the electrolyte.

Electrolyte: Silver nitrate solution (AgNO3) Anode (Positive Electrode): Silver (Ag) electrode Cathode (Negative Electrode): Spoon (usually made of a base metal like brass or copper)

Balanced Equation:

At the anode (oxidation): Ag(s) → Ag⁺(aq) + e⁻

At the cathode (reduction): Ag⁺(aq) + e⁻ → Ag(s)

Overall Electroplating Reaction: Ag⁺(aq) + Base Metal(spoon) → Ag(s) (plated layer) + Base Metal ion(s)

In this process, silver ions (Ag⁺) from the silver electrode are reduced at the cathode (spoon), forming a layer of silver on the spoon’s surface.

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