Question

The fraction of total current carried by the cation or anion is termed as (a) fractional number (b) speed number (c) carrier number (d) transport number

Short answer

The correct term that refers to the fraction of total current carried by the cation or anion is (d) transport number.

Step-by-step solution

Understand the Terminologies

Firstly, it is essential to have clear knowledge about the basic terms related to electrochemistry such as cations, anions and the type of numbers mentioned in the options (a) fractional number, (b) speed number, (c) carrier number, (d) transport number. Cations and anions are positively and negatively charged ions respectively. As for the types of numbers mentioned, only one type actually refers to the property described in the question.

Identify the Correct Term

Next, it is necessary to correlate the term that is used to specify the fraction of total current carried by the cation or anion. None of the terms 'fractional number', 'speed number', or 'carrier number' are used in the context of electrochemistry to refer to this property. Therefore, by process of elimination and also by factual knowledge, we can determine that the correct term is 'transport number'.

Confirm and Be Sure of the Answer

Lastly, for added confirmation, it's good practice to double-check the answer. In the field of electrochemistry, 'transport number' (also known as transference number) is the term which is used to indicate the fraction of total current carried by either the cation or anion.

Key concepts

Transport Number

The transport number is an important concept in electrochemistry. When an electric current passes through a solution, not all the ions carry the current equally. The transport number represents the fraction of the total current carried by either cations or anions in the solution. This means that the transport number evaluates the contribution of each ion to the movement of charge.

Transport numbers can vary depending on the ion's mobility in the solution and the concentration of ions. They are fundamental in understanding how electrolytes conduct electricity and how materials involve different ions' speed under the influence of an electric field.

• Transport numbers range from 0 to 1.
• If the transport number is high, it means that the ion type carries most of the current.
• Transport numbers are crucial in studying battery performance and chemical reactions.

By knowing the transport numbers, scientists can better design electrochemical systems, optimize energy storage devices, and select materials for specific applications.

Cations

Cations are positively charged ions that play a crucial role in electrochemistry. They are formed when an atom or molecule loses one or more electrons, resulting in a positive charge. For example, a sodium atom (Na) loses an electron to become a sodium cation (Na⁺).

In electrochemical reactions, cations migrate toward the negative electrode (cathode) under the influence of an electric field. Their movement is integral in maintaining charge balance and facilitating electrical conductivity.

• Cations are often metals like sodium, potassium, or calcium.
• They are crucial in processes such as electrolysis and battery operation.
• The size and charge of cations influence their mobility and transport number.

Understanding cations helps one grasp how varying factors like ion size and concentration affect the efficiency and effectiveness of electrochemical processes.

Anions

Anions are negatively charged ions, formed when an atom or molecule gains electrons. These ions are essential in maintaining electrical neutrality in solutions. For instance, when a chlorine atom gains an electron, it becomes a chloride anion (Cl⁻).

Anions, like cations, migrate through solutions, but they move towards the positive electrode (anode). Their movement and interaction with cations are vital in many electrochemical reactions and applications.

• Anions include species like chloride, nitrate, or sulfate.
• They contribute significantly to the ionic conductivity of a solution.
• The characteristics of anions, such as size and charge, can affect their transport number.

Analyzing anions aids in understanding how materials conduct electricity and how different ions interact within an electrochemical cell. This knowledge is indispensable in designing efficient energy solutions and understanding electrochemical phenomena.