Problem 6 - Chemistry in 30 days

Question

Faraday's law of electrolysis is related to the (a) atomic number of the cation (b) atomic number of the anion (c) equivalent mass of the electrolyte (d) speed of the cation

Step-by-Step Solution

Answer

(c) equivalent mass of the electrolyte.

Step 1: Understanding Faraday's Law of Electrolysis

Faraday's law of electrolysis states that the amount of substance (usually in moles) deposited at an electrode through electrolysis is directly proportional to the quantity of electricity that flows through the circuit. This is mathematically represented as \( W = \frac{Q}{96500} \times \text{Equivalent Mass} \) where \( W \) is the mass of the substance, \( Q \) is the total electric charge in coulombs, and 96500 is Faraday's constant.

Step 2: Analyzing the Given Options

The options given relate to different properties of ions and the electrolyte involved in an electrolysis process. Faraday’s law is fundamentally built on the concept of equivalent mass, which relates to molar mass divided by valency, not atomic numbers or speeds.

Step 3: Determining the Correct Answer

Based on the relationship in Faraday’s law, the critical factor is the equivalent mass of the electrolyte (Option C), as it directly influences the proportionality of mass to charge. Atomic numbers and speed are not relevant in the calculation of mass deposited during electrolysis.

Key Concepts

Equivalent Mass

In the context of electrolysis, equivalent mass becomes a fundamental concept. It refers to the mass of a substance (typically an element or compound) that will combine with or displace a fixed amount of another substance. Think of it like a specific weight that balances chemical reactions at the atomic level.

To define it mathematically, equivalent mass is the ratio of the molar mass to the valency of a substance. For instance, the equivalent mass of an element can be given as:

• \( \text{Equivalent Mass} = \frac{\text{Molar Mass}}{\text{Valency}} \)

This value is crucial when determining how much of a particular substance can be deposited on an electrode during the process of electrolysis.

Thus, equivalent mass allows us to connect the molar world to the real world by helping calculate the exact weights deposited during electrolysis. This makes it integral to application of Faraday's Law, as it ensures the accurate calculation of chemical transformations occurring due to electricity.

Electrolysis

Electrolysis is a fascinating chemical process that involves the breaking down of a compound using electricity. Imagine a circuit where electricity flows through a liquid or solution, leading to chemical changes. This is the essence of electrolysis.

During this process:

• An external electrical current is applied to cause a non-spontaneous chemical reaction.
• The circuit typically consists of two electrodes: an anode and a cathode.
• At the anode, oxidation occurs (loss of electrons), while at the cathode, reduction takes place (gain of electrons).

This separation of charge allows for the breakdown of compounds into their individual elements or ions. The beauty of electrolysis lies in its ability to decompose stable compounds, such as water into hydrogen and oxygen, or extracting metals from ores. Through electrolysis, Faraday demonstrated how electric currents can bring about chemical changes, fundamentally changing our understanding of chemistry.

Faraday's Constant

Faraday's constant is a key player in the orchestra of electrolysis. Named after Michael Faraday, it denotes the charge of one mole of electrons. Its value is approximately 96,500 coulombs per mole.

In the context of Faraday's law of electrolysis:

• It acts as the proportionality constant, allowing us to calculate the amount of substance deposited during electrolysis from the electric charge passed.
• Mathematically, it's symbolized as \( F \):
• \( F = 96500 \, \text{C/mol} \)

This constant represents the link between electric charge and the macroscopic quantities of substances formed during electrolysis. It provides a direct connection between the microscopic scale of electron reactions and the measurable quantities we observe.

Understanding Faraday’s constant is crucial for accurately predicting the outcomes of electrolysis, thereby ensuring efficient and precise chemical processing.