The molecules

have the same molecular formula (C3H8O) but different chemical structures. (b) Which molecule do you expect to have a larger dipole moment? [Sections 11.2 and 11.5]

Video transcript

Welcome back everyone in this example, we need to consider the following structures with the same molecular formula C two H 60. Which we should recall is for the structure of ethanol. We need to identify the compound that would have the larger dipole moment. So we need to focus on the strongest guy polls in each of these structures and finding the most electro negative atoms in structure one. We can see that we have carbon and oxygen here. But we also recognize that we have our oxygen directly bonded to a hydrogen. And we want to recall that hydrogen bonding is one of the stronger inter molecular forces. So we want to compare the electro negativity difference between this type of bond in structure one to our structure to where we can recognize that we have oxygen bonded to carbon here as our two most electro negative atoms. We don't have a oxygen directly bonded to a hydrogen atom. So we don't have hydrogen bonding here. And when we recall our electro negativity trend on our periodic table, which increases as we go towards the top right where florian is on our periodic table, we would agree that oxygen is more electro negative than carbon and therefore oxygen will have a slightly negative die pull on itself where the carbon atoms will have a slightly positive di pull on themselves. However, we have a stronger inter molecular force associated with structure one versus structure to where we only have dipole dipole inter molecular force and so we can say that our electro negativity difference between our oxygen hydrogen bond instructor one is greater than the election negativity difference between the carbon oxygen bond instructor too. And that is due to the fact that we agree that hydrogen bonding is a stronger inter molecular force than dipole dipole. And so for our final answer, we would say that the compound with the larger dipole moment is going to be structure one. So we're going to just outline the entire structure since this is the entire answer here of structure one. So I hope everything I reviewed was clear. If you have any questions, leave them down below and I will see everyone in the next practice video.