Conduction of Electricity Through Liquids and Gases

Conduction of electricity occurs in different media through the movement of charge carriers. While metals conduct through electrons, liquids and gases have unique mechanisms.

1. Conduction Through Liquids (Electrolysis)

Liquids that conduct electricity are known as electrolytes. This process usually involves chemical changes.

• Electrolytes: Liquids or solutions that contain ions and can conduct electricity (e.g., dilute H₂SO₄, CuSO₄ solution, molten NaCl).
• Non-electrolytes: Liquids that do not contain ions and cannot conduct electricity (e.g., pure water, kerosene, alcohol, sugar solution).
• Electrodes: The conductors (usually rods or plates) through which current enters or leaves the electrolyte. The positive electrode is the Anode, and the negative is the Cathode.
• Ions: Charged atoms or groups of atoms. Positive ions (Cations) move to the cathode, while negative ions (Anions) move to the anode.

2. Faraday's Laws of Electrolysis

Michael Faraday established two fundamental laws governing the mass of substances deposited during electrolysis:

• First Law: The mass (m) of a substance liberated at an electrode is directly proportional to the quantity of electricity (Q) passed through the electrolyte.
  Formula: m = zQ = zIt (where z is the Electrochemical Equivalent, I is current, and t is time).
• Second Law: When the same quantity of electricity is passed through different electrolytes, the masses of the substances liberated are proportional to their chemical equivalents.

3. Applications of Electrolysis

Electrolysis is used extensively in industries:

• Electroplating: Coating a cheaper metal with a more expensive one (e.g., silver-plating a spoon) to prevent corrosion or improve appearance.
• Purification of Metals: Refining metals like copper.
• Extraction of Metals: Obtaining reactive metals like Sodium and Aluminum from their ores.
• Calibration of Ammeters: Using the known mass of copper deposited to verify the accuracy of an ammeter.

4. Conduction Through Gases

Under normal conditions, gases are insulators. However, they can conduct electricity under low pressure and high potential difference.

• The Process: In a discharge tube, as pressure drops (around 0.01 mmHg), the gas begins to glow. Eventually, a stream of particles called Cathode Rays is produced.
• Cathode Rays: These are streams of fast-moving electrons. They travel in straight lines, possess kinetic energy, and are deflected by magnetic and electric fields.
• Applications: Fluorescent lamps, Neon signs for advertising, Cathode Ray Oscilloscopes (CRO), and X-ray tubes.