CHEMISTRY SLET QUESTION
The fraction of total current carried by an ion is called its transport number. Which of the following methods is commonly used for its experimental determination?
- (A) Ostwald's Dilution Method
- (B) Hittorf's Method
- (C) Moving Boundary Method
- (D) Both (B) and (C)
Correct Answer: (D) Both (B) and (C)
Explanation:
The transport number (also known as the transference number) is the fraction of the total electric current carried by a specific ionic species.
There are two primary experimental techniques to measure this:
- Hittorf's Method: Based on the change in concentration of the electrolyte around the electrodes (anode and cathode compartments) during electrolysis.
- Moving Boundary Method: A more accurate method involving the observation of the movement of a sharp boundary between two different electrolyte solutions under the influence of an electric field.
Note: The sum of transport numbers for all ions in a solution is always equal to 1 (t+ + t- = 1).