boiling point example

[bellaha4F]

in one of the worksheet answer key it says that the boiling point of KCl is higher than KI. however I thought that since I is bigger than Cl, KI should have a higher boiling point?

[Baoying Li 1B]

I think that the molar mass only works for London dispersion forces.
The dominant intermolecular force of KCl and KI is ion-ion which depends on the polarity. The higher the difference of electronegativity between elements, the higher the boiling point. Cl has a higher electronegativity than I. So KCl has a higher boiling force.

[Deana Moghaddas 3E]

Cl is more electronegative than I so KCL has higher boiling point.

[Miriam Villarreal 1J]

The greater forces of attraction will result in higher boiling and melting points because It takes more energy to separate the molecules from each other. Meanwhile a nonpolar molecule such as is symmetrical and has no positive or negative end.