Question

The heat of hydration of $C{a}^{2+},S{r}^{2+}$ and $B{a}^{2+}$ in the decreasing order is:

• A. $C{a}^{2+}>S{r}^{2+}>B{a}^{2+}$
• B. $C{a}^{2+}>B{a}^{2+}>S{r}^{2+}$
• C. $S{r}^{2+}>B{a}^{2+}>C{a}^{2+}$
• D. $B{a}^{2+}>S{r}^{2+}>C{a}^{2+}$

Answer 1

The correct option is A $C{a}^{2+}>S{r}^{2+}>B{a}^{2+}$

Hydration energy depends on size and charge of cation, as size of cation increases, hydration energy decreases. Now, size is in the order of $C{a}^{2+}<S{r}^{2+}<B{a}^{2+}$ and hydration energy is therefore in the order of $C{a}^{2+}>S{r}^{2+}>B{a}^{2+}$.