write the structures of all the isomers of dichloroethene .which one of them they have a zero dipole moment?
Answers
Geometric (cis-trans) isomers are compounds which have the same chemical formula but differ in the spatial arrangement of the groups that are attached to a double bond or to a ring.
Example of geometric isomerism is 1,2-dichloroethene. In one case, the -Cl groups are on opposite sides (trans) of the double bond, and in the other case they are on the same side (cis)
Geometric isomers occur when atoms are restricted from rotating around a bond i.e. where we see restricted rotation somewhere in a molecule.
The exact magnitude require certain parameter without which you cannot find dipole moment. The parameter you require are charges over the atoms and distance between the charges and some certain angle of dipole moment vector with respect to reference line . Since lot of atoms are involved in this molecule this make calculation very complex at this level of studies. At this level if you even asked this question in IIT exam then they will mention the value of charge and distance between them and using the product of both values you can find the value of dipole moment in cis-isomer. However, in trans Di-chloro the dipole moment = 0 as dipole moment cancel each other due to electronegative chlorine atom each in opposite direction so need not have such parameters .
Cis dichloroethene have a specific value of 1.89 obtained through vector sum of dipole moments.