Question

which of the following will have maximum value of heat of hydration?
A. Na+
B. Cs+
C. Mg+2
D. Ca+2​

Answer 1

Answer:

C

Explanation:

Heat of hydration depends upon charge density

charge density = magnitude of charge/ size of ion

Answer 2

Among the following, the ion that has the maximum heat of hydration is $\[M{g^{2 + }}\]$. Thus, the correct option is C.

Explanation:

• The heat of hydration or the hydration energy depends upon the size of the ion and the charge on the ion.
• The smaller the size of the ion, the higher is the heat of hydration.
• The more is the charge on the ion, the higher is the heat of hydration.
• The increasing order of the size of the given ions can be given as:

        $\[M{g^{2 + }} < C{a^{2 + }} < N{a^ + } < C{s^ + }\]$

• The size of the $\[M{g^{2 + }}\]$ ion is the smallest and has a +2 charge. Therefore, the heat of hydration will be highest for $\[M{g^{2 + }}\]$.