# Question #67b00

Jul 20, 2015

In order of decreasing strength of intermolecular forces: $175 \text{^@"C" > 80""^@"C" > 52""^@"C}$.

#### Explanation:

There is a direct relationship between the melting point of a substance and the strength of its intermolecular forces.

Simply put, stronger intermolecular forces lead to higher melting points.

The idea is very simple - in order to melt something, you need to provide it with enough energy to disrupt the intermolecular forces that are keeping the molecules or ions together.

When in a solid phase, the molecules are stuck together in giant structures. In order to get them to move away from one another, you need to provide the structure with enough energy to overcome the intermolecualr forces of attraction.

This is why you need more energy to disrupt stronger intermolecular forces of attraction than you need weaker intermolecular forces.

Of course, more energy is equivalent to a higher melting point. As a result, the substance that has the highest melting point will have the strongest intermolecular forces of attraction.

Therefore, in decreasing order of IMF strength, you have

$175 \text{^@"C" > 80""^@"C" > 52""^@"C}$.