Question

How is melting point related to the intermolecular forces of attraction?

Answer 1

To determine the answer we should know what the melting point is and what intermolecular forces of attraction are. The melting point is the temperature required to convert the solid phase into the liquid phase. The melting point of the compound depends upon the strength of the forces present in the compound

Complete step by step answer:
- When we heat a compound its temperature increases. The temperature at which solid starts to convert into liquid is known as melting point. At melting point solid and liquid both phases exist in equilibrium.
- Intermolecular forces are the attraction or repulsion forces present between the molecules. When we heat the compound these forces break, so the compound decomposes and then converts into the liquid state.
- If the intermolecular forces of attraction will be weak then at low temperature the compound will decompose or we can say the compound will melt at low temperature so, the melting point of the compound will be low. If the intermolecular forces of attraction will be strong then we have to supply the heat with high temperature for the decomposition of the compound or the compound will melt at high temperature so, the melting point of the compound will be high.
- So, the melting point directly depends upon the strength of intermolecular forces of attraction. Therefore, melting point is directly proportional to the strength of the intermolecular forces of attraction.

Note:

Atoms held together by the covalent bond are known as covalent molecules whereas if the atoms are held together by an ionic bond are known as ionic molecules. Molecules are held together by the intermolecular force of attraction to form compounds.
The covalent compounds have van der Waals force of attraction. The ionic compound has the electrostatic force of attraction. Electrostatic forces are stronger than van der Waals forces.
So, covalent molecules have a low melting point because covalent molecules are held by van der Waals force of attraction which is a weak force.