Revision: Electrolysis Chemistry (English Medium) ICSE Class 10 CISCE

Non-electrolytes are compounds that do not conduct electric current in either solid state or aqueous solution because they do not produce ions in solution.
Example: Sugar solution.

Substances like most metals and alloys that allow an electric current to pass through them without undergoing any chemical change are called conductors of electricity.

Electrolytes are compounds which either in aqueous solution or in molten state allow electric current to pass through them.

It is the process of decomposition of a chemical compound in aqueous solution or in molten state accompanied by a chemical change by using direct electric current. 

The atoms which carry a negative charge are called anions.

A nonconducting vessel containing two electrodes immersed in a solution of electrolytes used to bring about a chemical reaction.

It is a device used to convert chemical energy into electrical energy.

Two metal plates or wires or graphite rods or gas carbon rods immersed in the electrolyte through which the current enters and leaves the electrolytic cell are called electrodes.

The electrode connected to the positive terminal of the battery is called anode.

The electrode connected to the negative terminal of the battery is called cathode.

The atoms or groups of atoms which carry a positive or a negative charge are known as ions.

Atoms which carry positive charge are called cations.

 An oxidising agent is one that oxidises other substances by either accepting electrons or by providing oxygen or an electronegative ion [or by removing hydrogen or an electropositive ion].

In the electronic concept, oxidation is defined as a process in which an atom or an ion loses electron(s).

A reducing agent is one that reduces other substances by providing electrons, or by providing hydrogen or an electropositive ion, (or by removing oxygen or an electronegative ion). Thus, in the above examples, hydrogen, carbon, hydrogen sulphide and ammonia are the reducing agents.

OR

The substance that brings about reduction is called a reductant, or a reducing agent.

In the electronic concept, reduction is defined as a process in which an atom or an ion gains electron(s).

OR

Reduction is also defined as a chemical process which involves removal of oxygen or addition of hydrogen.

OR

The chemical reactions in which reactants gain hydrogen are called ‘reduction’ reactions. Similarly, the reaction in which a reactant loses oxygen to form the product is also called reduction reaction.

The electrovalent compounds consist of an aggregate of oppositely charged ions held in their positions by the strong electrostatic forces of attraction.

The process due to which an ionic compound dissociates into ions in the fused state or in aqueous solution is called electrolytic dissociation.

The process by which polar covalent compounds are converted into ions, in water solution, is called ionisation.

The standard potentials of a number of electrodes have been determined using standard hydrogen electrodes. These electrodes with their half reactions are arranged according to their decreasing standard potentials; this arrangement is called an electrochemical series.

Based on the ease with which atoms of metals lose electrons to form positively charged ions, the metals are arranged in a series known as the electrochemical series.

or

The arrangement of electrodes in order of their decreasing standard reduction potentials is called electrochemical series.

Electroplating is a process in which a thin film of a metal like gold, silver, nickel, chromium, etc. gets deposited on another metallic article with the help of electricity.

Electrolytic refining is a process by which metals containing impurities are purified electrolytically to give a pure metal.

Electrometallurgy is the process of extraction of metals by electrolysis.

Statement:

Electrolytes, when dissolved in water, dissociate into free ions that help conduct electricity.

Proof / Explanation:

1. Electrolytes break into cations (+) and anions (−) in water.
2. These ions carry an electric charge and allow current to flow.
3. More ions in solution = higher conductivity.
4. The number of + and − charges stays balanced (electrolytic equilibrium).
5. Non-electrolytes (like sugar) do not form ions, so they don’t conduct electricity.
6. The degree of dissociation indicates how much an electrolyte dissociates into ions.

Modern concept:

• Arrhenius said water causes ionisation.
• Modern view: Electrolytes are ionic even in solid form, but ions are held tightly.
• Water breaks these forces, allowing ions to move freely.

Conclusion:

Electrolytes conduct electricity in solution because their ions are free to move. Water enables this movement by breaking ionic forces.

• Ion Migration: In electrolysis, cations move to the cathode and anions to the anode.
• Electron Exchange: The number of electrons lost at the anode = gained at the cathode, ensuring charge balance.
• Product Formation: Products form only at electrode surfaces where ions are discharged by electron transfer.
• Redox Reaction: Electrolysis is a redox process:
  Reduction at the cathode (gain of electrons)
  Oxidation at the anode (loss of electrons)
• Current Type: Only Direct Current (DC) can cause electrolysis; Alternating Current (AC) has no chemical effect.