Difference in B.P. of cis/trans isomer can be :
Difference in B.P. of cis/trans isomer can be :
The correct option is A larger if polar bonds are present in the molecule
There must be stronger intermolecular forces between the molecules of the cis isomers than between trans isomers. This we can understand by taking eg. of 1,2-dichloroethane. Both of the isomers have same atoms joined up in the same order. The difference between the two is that the cis isomer is a polar molecule whereas the trans isomer is non-polar. Both molecules contain polar chlorine-carbon bonds, but in the cis isomer, they are both on the same side of the molecule. That means that one side of the molecule will have a slight negative charge while the other is slightly positive. The molecule is therefore polar. Boiling point depends upon intermolecular interactions which over here is more in cis due to its net dipole moment.
There must be stronger intermolecular forces between the molecules of the cis isomers than between trans isomers. This we can understand by taking eg. of 1,2-dichloroethane. Both of the isomers have same atoms joined up in the same order. The difference between the two is that the cis isomer is a polar molecule whereas the trans isomer is non-polar. Both molecules contain polar chlorine-carbon bonds, but in the cis isomer, they are both on the same side of the molecule. That means that one side of the molecule will have a slight negative charge while the other is slightly positive. The molecule is therefore polar. Boiling point depends upon intermolecular interactions which over here is more in cis due to its net dipole moment.
