Explain why cis- alkenes typically have a lower boiling point than trans alkenes.

Define cis and trans alkenes:Carbon to carbon single bonds can freely rotate to give a carbon chain that can take on a number of shapes (this is to do with the overlap of p - orbitals to form pi bonds) however the rigidity of carbon to carbon double bonds means they cannot carry out this free rotation and as such form rigid shapes. A cis alkene has the two carbon chains on the same side of the carbon bond whereas a trans alkene has the carbon chain on opposite sides of the carbon to carbon double bond. What affects boiling point?A substance changes state from a liquid to a gas when the intermolecular interactions are overcome, specifically van der waals forces. The greater the degree of Van der waals forces, the more energy will be needed to overcome them and the higher the boiling point of the substance will be.Cis vs trans boiling point:Cis alkenes form "C" shapes that do not line up as easily as the trans alkenes that form lines that pack together much better. Cis alkenes therefore have a smaller degree of van der waals forces than trans alkenes which take less energy to overcome, therefore cis alkenes have a lower boiling point than trans alkenes.