Chapter 9, Problem 115A

Distinguish between an ionic compound and a molecular compound dissolved in water. Do all molecular compounds ionize when dissolved in water? Explain.

Interpretation Introduction

Interpretation:

An ionic compound needs to be distinguished from a molecular compound dissolved in water. Whether all molecular compounds ionize when dissolved in water or not needs to be explained.

Concept introduction:

Ionic compounds are made up of ions and these ions are held together by the electrostatic forces of attraction such as LiF, LiCl, LiBr etc.

Molecular compounds tend to form discrete molecules such as ${\text{H}}_{\text{2}}\text{O,}{\text{N}}_{\text{2}}\text{,}{\text{O}}_{\text{3}}$ etc.

Answer to Problem 115A

On dissolving in water, ionic compounds dissociate but molecular compounds do not dissociate.

Explanation of Solution

An ionic compound can undergo dissociation into cation and anion when the compound is dissolved in water. A molecular compound generally does not dissociate but they lose the rigid intermolecular structure when the compound is dissolved in water.

Some molecular compounds can dissociate into water such as HCl. This is due to the present of polar covalent bond between H and Cl atom.

Conclusion

Ionic compounds dissociate but molecular compounds generally do not dissociate on dissolving in water.