The Transport Number of Cd2+ ion in Concentrated Solutions of CdI2 is Negative

Explanation:

- Definition: The transport number is the fraction of the total current carried by an ion in the electrolyte solution. It is a measure of the ion's mobility in the solution.
- Concentrated Solutions of CdI2: In concentrated solutions of CdI2, the Cd2+ ion is surrounded by a large number of I- ions. This results in the formation of a complex ion, CdI42-, which has a negative charge.
- Negative Transport Number: Due to the formation of the CdI42- complex ion, the transport number of Cd2+ ion becomes negative. This means that the Cd2+ ion carries a negative fraction of the total current in the solution.
- Explanation: The negative transport number of Cd2+ ion can be explained by the fact that the Cd2+ ion is no longer a free ion in the solution. It is now a part of the CdI42- complex ion, which carries a negative charge. Therefore, the transport of Cd2+ ion is hindered by the presence of the negatively charged complex ion.
- Significance: The negative transport number of Cd2+ ion in concentrated solutions of CdI2 is important in electrochemical processes. It affects the efficiency of electroplating and other electrochemical reactions involving Cd2+ ion. It also affects the behavior of Cd2+ ion in biological systems, where it can have toxic effects.

Conclusion:

In conclusion, the transport number of Cd2+ ion in concentrated solutions of CdI2 is negative due to the formation of the CdI42- complex ion. This has important implications in electrochemical and biological systems.