11.38 (a) Would you expect the viscosity of n-pentane, CH3CH2CH2CH2CH3, to be larger or smaller than the vis- cosity of n-hexane, CH3CH2CH2CH2CH2CH3? (b) Would you expect the viscosity of neopentane, (CH3)4C, to be smaller or larger than the viscosity of n-pentane? (See Fig- ure 11.6 to see the shapes of these molecules.) Linear molecule larger Surface area enhances intermolecular contact and increases dispersion force. n-Pentane (CsH12) 309.4 K bp Spherical molecule-smaller surface area diminishes intermolecular contact and decreases dispersion force. Neopentane (C5H12) bp = 282.7 K Figure 11.6 Molecular shape affects intermolecular attraction. Molecules of n-pentane make more contact with each other than do neopentane molecules. Thus, n-pentane has stronger intermolecular attractive forces and therefore a higher boiling point.

11.38 (a) Would you expect the viscosity of n-pentane, CH3CH2CH2CH2CH3, to be larger or smaller than the vis- cosity of n-hexane, CH3CH2CH2CH2CH2CH3? (b) Would you expect the viscosity of neopentane, (CH3)4C, to be smaller or larger than the viscosity of n-pentane? (See Fig- ure 11.6 to see the shapes of these molecules.) Linear molecule larger Surface area enhances intermolecular contact and increases dispersion force. n-Pentane (CsH12) 309.4 K bp Spherical molecule-smaller surface area diminishes intermolecular contact and decreases dispersion force. Neopentane (C5H12) bp = 282.7 K Figure 11.6 Molecular shape affects intermolecular attraction. Molecules of n-pentane make more contact with each other than do neopentane molecules. Thus, n-pentane has stronger intermolecular attractive forces and therefore a higher boiling point.

Chemistry & Chemical Reactivity

9th Edition

ISBN:9781133949640

Author:John C. Kotz, Paul M. Treichel, John Townsend, David Treichel

Publisher:John C. Kotz, Paul M. Treichel, John Townsend, David Treichel

Chapter11: Intermolecular Forces And Liquids

Section: Chapter Questions

Problem 45SCQ: Liquid ethylene glycol, HOCH2CH2OH, is one of the main ingredients in commercial antifreeze. Would...

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Liquid ethylene glycol, HOCH2CH2OH, is one of the main ingredients in commercial antifreeze. Would you predict its viscosity to be greater or less than that of ethanol, CH3CH2OH?
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8.48 Why must the vapor pressure of a substance be measured only after dynamic equilibrium is established?
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The types of intermolecular forces in a substance are identical whether it is a solid, a liquid, or a gas. Why then does a substance change phase from a gas to a liquid or to a solid?
(a) Would you expect the viscosity of n-pentane,CH3CH2CH2CH2CH3, to be larger or smaller than the viscosityof n-hexane, CH3CH2CH2CH2CH2CH3? (b) Wouldyou expect the viscosity of neopentane, 1CH324C, to besmaller or larger than the viscosity of n-pentane? (See Figure11.6 to see the shapes of these molecules.)
Which has the lowest viscosity? C6 H14, C12H26, or C18H28