Why is the vapor pressure of cis-dibromoethene lower than the vapor pressure of trans-dibromoethene?

Question

Quizplus · Accepted Answer

The vapor pressure of a substance is related to the strength of the intermolecular forces between the molecules in the liquid phase. In general, the stronger the intermolecular forces, the lower the vapor pressure. cis-dibromoethene has two bromine atoms on the same side of the carbon-carbon double bond, creating a dipole moment that allows for stronger dipole-dipole intermolecular forces compared to the trans isomer, which has the bromine atoms on opposite sides of the double bond. Therefore, the vapor pressure of cis-dibromoethene is lower than trans-dibromoethene due to stronger intermolecular forces. Choice E, dipole-dipole forces, is the best choice.

Why Is the Vapor Pressure of Cis-Dibromoethene Lower Than the Vapor