Hydration Enthalpy and Lattice Enthalpy (Group 2)

Q.

Halides of alkaline earth metals form hydrates such as MgCl₂.6H₂O, CaCl₂.6H₂O, BaCl₂.2H₂O and SrCl₂.2H₂O. This shows that halides of group 2 elements

1. Are hygroscopic in nature

2. Can act as dehydrating agents

3. Can absorbs moisture from air

4. All of the above

Q. Solubility of an ionic compound in water is mainly dependent on:
a. Lattice enthalpy
b. Hydration enthalpy
Both these factors oppose each other, and the resultant of these factors determines the solubility of an ionic compound in water. If the lattice enthalpy has a larger value, the compound is less soluble. If the hydration enthalpy has larger value, the compound is highly soluble in water.

Compounds of alkaline earth metals are less soluble than alkali metals, due to:

1. Their high hydration enthalpy
2. Their high lattice enthalpy
3. Their increased covalent character
4. Their high ionisation enthalpy

Q. Solubility of an ionic compound in water is mainly dependent on:
a. Lattice enthalpy
b. Hydration enthalpy
Both these factors oppose each other, and the resultant of these factors determines the solubility of an ionic compound in water. If the lattice enthalpy has a larger value, the compound is less soluble. If the hydration enthalpy has larger value, the compound is highly soluble in water.

A compound is soluble in water if the hydration enthalpy is:

1. Greater than the lattice enthalpy
2. Less than the lattice enthalpy
3. Same as the lattice enthalpy
4. None of the above

Q. The right order of the solubility of sulphates alkaline earth metals is:

1. $Be>Ca>Mg>Ba>Sr$
2. $Mg>Be>Ba>Ca>Sr$
3. $Be>Mg>Ca>Sr>Ba$
4. $Mg>Ca>Ba>Be>Sr$

Q. Solubility of an ionic compound in water is mainly dependent on:
a. Lattice enthalpy
b. Hydration enthalpy
Both these factors oppose each other, and the resultant of these factors determines the solubility of an ionic compound in water. If the lattice enthalpy has a larger value, the compound is less soluble. If the hydration enthalpy has larger value, the compound is highly soluble in water.

Compounds of alkaline earth metals are less soluble than alkali metals, due to:

1. Their high hydration enthalpy
2. Their high lattice enthalpy
3. Their increased covalent character
4. Their high ionisation enthalpy

Q.

Property of the alkaline earth metals that increases with their atomic number is

1. Ionisation energy

2. Solubility of their hydroxides

3. Solubility of their sulphates

4. Electronegativity