Which member in each pair has the greater dispersion forces? (a) H2O or H2S,

Video transcript

Hello everyone. Today. We are being asked to compare the inter molecular dispersion force of. We have two compounds here. And so the first thing we're gonna do is we want to go through our answer choices. So right off the bat we can see That answer. Choice A is the correct one. And in a minute we'll go through why each of the other ones aren't the same, Aren't the correct answers. So when evaluating these compounds, we have to look at the molecular weight first to determine what inter molecular force they may have. And since we only have carbon, hydrogen and bro means we know we can only stick with di pole dipole interactions. And so they both have the same weight. So both of these have a weight of 175 g per mole. They will have the same number of carbons, hydrogen and bromine atoms. When you have smaller molecular weight, you generally have weaker inter molecular forces. And since they're the same, we have to move on to our second factor. So we set our first factor as we look at the molecular weight for a second we look at branch versus linear. And we'd say that branched compounds will have higher boiling points due to having less surface area. And so since we'll say that branched will have less of a boiling point due to less surface area to cover. And so since the second compound here is branched, it has a weaker inter molecular force and therefore the linear chain which is the first compound will therefore have a stronger inter molecular dispersion force. I hope this helped, and until next time.