Predict which substance in each pair has the highest viscosity. (b) Pentane or neopentane

Video transcript

Hello everyone today. We have the following problem, which are the following two substances is expected to have a higher viscosity. We have in octane or 2-4. Triumph, methyl plantain. So first let's define what viscosity is. So simply put viscosity is just the measure of the thickness of a liquid. So for an example, honey would have a higher viscosity than, say water because it is essentially the resistance against flow. So honey is going to flow at a slower rate than, say water. So what does viscosity depend on viscosity depends on the inter molecular forces or the strength of them? And the trend with that is that liquids that have high inter molecular forces tend to also have higher viscosity is. Moreover, we can also use the molecular shape to determine how low viscosity will be affected. So linear structures. So linear structures tend to have or linear structures with a larger surface area tend to stick together due to dispersion forces. So their viscosity is going to be higher and the same can be said for the opposite. So we can say that branch structures. So branched structures will have lower viscosity is because it's more easier, it's more easy to move them around. And so when we draw structures we'll have in octane and in octane is going to be consisting of eight carbons. So 24, 78. And then we're going to have our two, 24 try metal painting. First, we're gonna draw the parent structure. So plantain meaning there's five carbons And then we go to carbon three Or carbon to carbon two is going to have a metal two methods as well. It'll go to carbon four and that's going to have a method as well. And so we can look at these structures and say that in octane is going to be more symmetrical and be more linear. So in octane is going to be more layer and so therefore it's going to have stronger inter molecular forces and therefore a higher viscosity. We see here that 2-4 try mental. Plantain has three different branched out kill chains. So this molecule is branched and therefore it's going to have lower inter molecular forces and therefore a lower viscosity. So in examining which one of these would have a higher viscosity, we can say that in octane will have the higher viscosity overall. I hope this helped. And until next time.