Unlocking the Mysteries of Electrochemistry | Concepts and Definitions: For BISE, Federal Board, School and College level exams and Tests Preparation.

Electrochemistry is an essential branch of chemistry that deals with the relationship between electricity and chemical reactions. It has numerous applications in various fields, from electroplating to batteries. Understanding Electrochemistry is crucial for students preparing for BISE, Federal Board Exams, and various entry tests such as NEET, MDCAT, ETEA, CSS, PCS, PMA, NTS, and CTS. In this blog post, we will provide a concise overview of Chapter 7 of Class 9 level Chemistry notes on Electrochemistry. We will cover the definition of Electrochemistry, its widespread applications, the difference between Oxidizing and Reducing agents, Electrodes, and Electrolysis, Electrolytes and their types, basic level operations in electrochemical industries, and short notes on Tin, Zinc, Chrome, and Silver electroplating. This article is a comprehensive guide for students looking to understand the fundamentals of Electrochemistry and ace their exams.

Class 9 level Chemistry Notes on Chapter 7 "Electrochemistry" for BISE and Federal Board Examinations and Entry/Competitive tests preparations

Chemistry Notes of Electrochemistry for School and College level Students
From the Notes Library of H.E.S (Health, Education, and Skills)

Define the term Electro-Chemistry. What are its widespread applications?

Electro-Chemistry

The branch of Chemistry which deals with the inter-conversion of electrical and chemical energies is called Electro-Chemistry.

Applications of Electro-Chemistry

Electro-Chemistry has the following widespread applications.
In Batteries. The concept of Electro-Chemistry is used in batteries where chemical energy produces electrical energy.
In Laboratories. In laboratories, electrical measurements enable us to monitor all kinds of reactions.
In Industries. In industries, many different important chemicals are produced by electrochemical means.

What is the difference between oxidizing and reducing agents? Explain your answer with examples.

Differences between Oxidizing and Reducing agents

Sr#	Basis of distinction	Oxidizing agent	Reducing agent
1	Definition	Those chemical species that oxidized other substances but itself get reduced is called Oxidizing agent.	Those chemical species that reduces other substances but itself get oxidized is called Reducing agent.
2	Supply of Oxygen	Oxidizing agents always supply Oxygen in a chemical reaction.	Reducing agent always releases Oxygen in a chemical reaction.
3	Release of Hydrogen	Oxidizing agent always releases Hydrogen in a chemical reaction.	Reducing agents always supply Hydrogen in a chemical reaction.
4	Gain of electrons	Oxidizing agents always gain electrons in a chemical reaction.	Reducing agents always lose electrons in a chemical reaction.
5	Decrease in Oxidation state	The Oxidation state/number of Oxidizing agents decreases in a chemical reaction.	The Oxidation state/number of Reducing agents increases in a chemical reaction.
6	Electronegative/ Electro-positive nature	Oxidizing agents are always electronegative in nature.	Reducing agents are always electro-positive in nature.
7	Examples	CO₂, O₂, KMnO₄, K₂Cr₂O₇, Cl₂, Br₂ etc.	H₂, C, H₂S, CO, SO₂, Na, and all metals.

Write short notes on (i) Electrodes, and (ii) Electrolysis

Electrodes

The Metallic plates, rods, or wires through which electrons enter or leave the electrolyte in a cell are called Electrodes.

Explanation

Electrodes may be wires or rods of an Electrolytic cell. The wires (Electrodes) may be positive called Anode or may be negative called Cathode. While the Ions that move towards the negative electrode are called Cations and the Ions that move towards the positive electrode are called Anion.

Anode: It is connected to the positive terminal of the battery. Anions move towards the anode and leave the electrons in an electrolytic cell. Oxidation occurs at the anode.
Cathode: It is connected to the negative terminal of the battery. Cations move toward the cathode and gain electrons in an electrolytic cell. Reduction occurs at the cathode.

Electrolysis

The process of chemical decomposition of an electrolyte in a fused state or in solution, by the passage of electric current, is called Electrolysis.

Explanation

When we pass an electric current through the aqueous solution of Water (H₂O) and Salt (NaCl), Na⁺ will move towards Cathode while Cl^- will move towards Anode. The anions liberate electrons at the anode and pass through the outer surface to the cathode.

Define and explain the term electrolytes. What are its types?

Electrolytes

A substance that in an aqueous solution dissociates into positive and negative ions and conducts electricity is called Electrolyte.

Acids, Bases, and Salts are examples. Depending on the degree of ionization or dissociation Electrolytes are classified into the following two types

Types of electrolytes

a. Strong Electrolytes

A substance that dissociates and conducts electric current to a high extent in an aqueous solution is called Strong Electrolytes.

For example, NaCl, NaOH (Sodium Hydro-Oxide), and HCl, etc.

NaOH _(aq) → Na⁺_(aq) + OH- _(aq)
NaCl _(aq) → Na⁺_(aq) + Cl- _(aq)
HCl _(aq) → H⁺_(aq) + Cl^-_(aq)

b. Weak electrolytes

A substance that dissociates and conducts electric current to a low extent in an aqueous solution is called Weak Electrolytes.

For example, NH₄OH (ammonium hydro-oxide), H₂CO₃(Carbonic Acid), CH₃COOH, etc.

NH₄OH _(aq) → NH₄⁺_(aq) + OH^-_(aq)
CH₃COOH_(aq) → CH₃COO^-_(aq) + H⁺_(aq)

c. Non-Electrolytes

Substances that do not ionize in an aqueous solution and thus do not conduct electricity are called Non-Electrolytes.

For example, Glucose, Urea, and Sugar

What are some of the operations in the Electrochemical industries?

Electrochemical industries

Electrochemical industries involve many electrochemical operations, some of which are given as

I. Electrochemical cells/batteries: Electrochemical cells/batteries are constructed between different electrodes and are available in markets where they are used in toys, calculators, pacemakers, flashlights, radios, etc.

II. Electroplating: In electroplating one metal is deposited on another metal for the purpose of durability, beauty, or repair.

III. Electrolytic production and refining of metals: Electrolytic production of metals e.g (Na) and Electrolytic refining of metals e.g. (Cu) are done in electrochemical industries to obtain metals in their purest form.

IV. Manufacturing of chemicals: In electrochemical industries many important chemicals like NaOH are prepared.

Write a short note on Tin (Stannum-Sn) plating.

The procedure of Tin plating/ Electroplating of Tin

In this process, the clean article to be Tin plated is made into the cathode. A pure sheet of Silver is made anode. The solution of Sodium stannate (Na2SnO3.3H2O) is used as an electrolyte. The two electrodes are then connected to the battery.

When an electric current is passed the atoms of Tin from the anode give electrons forming Sn+2 ions. The electrons reach the cathode through the external circuit where they are consumed by Sn+2 ions of the solution. Thus, Sn metal is deposited over the cathode. The anode is used up gradually and is replaced after some time.
Reactions: The reaction occurring at the cathode and anode are given below.

At anode: Sn _(s) → Sn⁺²_(aq) + 2 e^-

At Cathode: Sn⁺²_(aq) + 2 e^- → Sn_(s)

Write a short note on Zinc platting

Zinc plating

The deposition of zinc metal over other metals with the help of electricity is called Zinc platting or Zinc electroplating.

The procedure of Zinc plating

In this process, the clean article to be Zinc plated is made the cathode. A pure sheet of Zinc is made anode. The solution of Zinc Sulphate (ZnSO4) and Sulphuric Acid (H2SO4) is used as an electrolyte. The two electrodes are then connected to the battery.

When an electric current is passed the atoms of Zinc from the anode give electrons forming Zn+2 ions. The electrons reach the cathode through the external circuit where they are consumed by Zn+2 ions of the solution. Thus, Zinc metal is deposited over the cathode. The anode is used up gradually and is replaced after some time.

Reactions: The reaction occurring at the cathode and anode are given below.

At anode: Zn _(s) → Zn⁺²_(aq) + 2 e^-

At Cathode: Zn⁺²_(aq) + 2 e^- → Zn _(s)

Write a short note on Chrome plating.

The procedure of Chrome plating

In this process, the clean article to be Chromium plated is made the cathode. A pure sheet of Chromium is made of an anode. The solution of Chromium Sulphate (CrSO4) and Sulphuric Acid (H2SO4) is used as an electrolyte. The two electrodes are then connected to the battery.

When an electric current is passed the atoms of Chromium from the anode give electrons forming Cr+3 ions. The electrons reach the cathode through the external circuit where they are consumed by the Cr+3 ions of the solution. Thus, Chromium metal is deposited over the cathode. The anode is used up gradually and is replaced after some time.

Reactions: The reaction occurring at the cathode and anode are given below.

At anode: Cr _(s) → Cr⁺³_(aq) + 3 e^-

At Cathode: Cr⁺³_(aq) + 3 e^- Cr _(s)

Write a short note on Silver plating.

The procedure of Silver plating

In this process, the clean article to be Silver plated is made the cathode. A pure sheet of Silver is made anode. The solution of Silver cyanide (AgCN) is used as an electrolyte. The two electrodes are then connected to the battery.

When an electric current is passed the atoms of Silver from the anode give electrons forming Ag⁺¹ ions. The electrons reach the cathode through the external circuit where they are consumed by Ag⁺¹ ions of the solution. Thus, Ag metal is deposited over the cathode. The anode is used up gradually and is replaced after some time.