Enthalpies Of Solution

Question 1

What is enthalpy of solution?

Answer 1

The enthalpy change that takes place when one mole of a compound is dissolved in water under standard conditions

Question 2

What is enthalpy change of hydration?

Answer 2

The enthalpy change that takes place when one mole of isolated gaseous ions are dissolved in water forming one mole of aqueous ions under standard conditions

Question 3

How does ionic size affect hydration enthalpy?

Answer 3

As ionic radius increases:
- attraction between ions and water molecules decreases
- so hydration enthalpy is less negative

Question 4

How does ionic charge affect hydration enthalpy?

Answer 4

As ionic charge increases:
- attraction between ions and water molecules increases
- hydration energy becomes more negative

Question 5

How can solubility be predicted using enthalpy values?

Answer 5

If the sum of hydration enthalpies is larger than the lattice enthalpy then the compound should dissolve