Question

Ion having highest hydration enthalpy among the given alkaline earth metal ions is:

• A. Be⁺²
• B. Mg⁺²
• C. Ca⁺²
• D. Ba⁺²

Answer 1

The Correct Option is A

The question asks about the ion with the highest hydration enthalpy among the given alkaline earth metal ions. Let's understand what hydration enthalpy is and how it applies to these ions.

Hydration Enthalpy is the amount of energy released when one mole of ions undergo hydration by water molecules. It is influenced by the charge and size of the ion. A higher charge and smaller size result in a higher hydration enthalpy because the ion can interact more strongly with water molecules. In general:

• Smaller ions have higher charge density and thus higher hydration enthalpies.
• Greater charge on the ion also contributes to a higher hydration enthalpy as it interacts more strongly with the water molecules.

Now, let's consider the given ions:

1. Be²⁺
2. Mg²⁺
3. Ca²⁺
4. Ba²⁺

The Be²⁺ ion is the smallest among these ions. Hence, it has the highest charge density. Consequently, it interacts most strongly with the surrounding water molecules, resulting in the highest hydration enthalpy. This is consistent with the trend in the periodic table for alkaline earth metals where smaller ions like Be²⁺ have higher hydration enthalpies compared to Mg²⁺, Ca²⁺, and Ba²⁺.

Conclusion: The Be²⁺ ion has the highest hydration enthalpy among the given options, making it the correct answer.