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Ch.11 - Liquids & Phase Changes

Chapter 11, Problem 23a

Predict which substance in each pair has the highest viscosity. (a) Hexane 1CH3CH2CH2CH2CH2CH32 or 1-hexanol 1CH3CH2CH2CH2CH2CH2OH2

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Hey everyone. So here it says identify the compound with the higher viscosity between each pair. Remember viscosity is just the resistance to flow something that is viscous moves very slowly. Think of honey molasses, Think of black tar, that's used for roads all those are highly viscous. Now here we're going to say that the stronger your inter molecular force than the higher your viscosity. So if we take a look here in option one, we have ethanol versus dimethyl ether. Methanol has an older age group. H is directly connected to hype to oxygen, which means that we have hydrogen bonding. Alright so the first one has H bonding and then dimethyl ether there's an oxygen right there in the center it's very electro negative which means the whole molecule is polar. It's a polar Covalin compound. So it is a disciple disciple, which one is a stronger inter molecular force hydrogen bonding. So ethanol will be more viscous. Next we have to hydrocarbons meaning they're only composed of carbon and hydrogen. So they're both non polar and they have London dispersion forces as their major inter molecular force. The one that weighs more is the one that has a stronger London dispersion force. If we take a look, the first one has five C. H. Two S in the middle and this one has seven so that one weighs more. So this one would be stronger and therefore be more viscous. Finally we have here Butin all. Well actually no that's Penton all fentaNYL and then here we have a glide glide claw which means it has 20. H groups, ethylene glycol. You don't need to know the names. I'm just giving the names here for this question. So they both have a wage groups, but the second one has to ohh groups so it has more ohh groups which means it has more hydrogen bonding, which means it would be stronger and therefore it has a higher viscosity. So here the second structure would be more viscous. So this is how we compare the viscosity of each of the pairs, the stronger the inter molecular force, the higher the viscosity.