Question

Which among the following ionic species has least precipitating power?

• A. Cl\(^-\)
• B. SO\(_4^{2-}\)
• C. Mg\(^{2+}\)
• D. Al\(^{3+}\)

Hint:

In terms of precipitating power, ions with higher charges and smaller sizes are more effective. Chloride, being a monovalent ion, has the least precipitating power.

Answer 1

The Correct Option is A

Step 1: Understanding precipitating power.
Precipitating power refers to the ability of an ion to form insoluble salts with other ions. The higher the charge and smaller the ion, the stronger its precipitating power.

Step 2: Analyzing the options.
(A) Cl\(^-\): Chloride ion has a low charge and relatively larger size, making it the least effective in precipitating other ions.
(B) SO\(_4^{2-}\): Sulfate ions have a higher charge than chloride ions and can precipitate more effectively.
(C) Mg\(^{2+}\): Magnesium ions have a +2 charge, which gives them a stronger precipitating power compared to Cl\(^-\).
(D) Al\(^{3+}\): Aluminum ions have the highest charge (+3), making them the strongest precipitant among the options.

Step 3: Conclusion.
The least precipitating ion is (A) Cl\(^-\), as it has the lowest charge and largest size compared to the other options.