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baum (awb464) – H11: Solids and Liquids – mccord – (50970)1Thisprint-outshouldhave25questions.Multiple-choice questions may continue onthe next column or page – find all choicesbefore answering.00110.0 pointsWhat would be the most significant type ofintermolecular forces in a liquid sample offluoroform (CHF3)?1.ionic2.dispersion3.hydrogen bonding4.covalent5.dipole-dipolecorrectExplanation:London forces, dispersion forces, van derWaals or induced dipoles all describe the sameintermolecular force.London forces are in-duced, short-lived, and very weak. Moleculesand atoms can experience London forces be-cause they have electron clouds.Londonforces result from the distortion of the elec-tron cloud of an atom or molecule by thepresence of nearby atoms or molecules.Permanent dipole-dipole interactions arestronger than London forces and occur be-tween polar covalent molecules due to chargeseparation.H-bonds are a special case of very strongdipole-dipole interactions.They only occurwhen H is bonded to small, highly electroneg-ative atoms – F, O or N only.Ion-ion interactions are the strongest due toextreme charge separation and occur betweenionic molecules.They can be thought of asboth inter- and intramolecular bonding.CHF3is a polar molecule that does not con-tain H bonds; therefore, dipole-dipole forceswill be the most significant type of intermolec-ular forces present.00210.0 pointsForces between particles (atoms, molecules,or ions) of a substance are called1.None of these2.intermolecular forces.correct3.intramolecular forces.4.armed forces.Explanation:Bonds within molecules or formula units arecalled intramolecular forces.Bonds betweenparticles are called intermolecular forces.00310.0 pointsWhat is the predominant intermolecular forcebetween IBr molecules in liquid IBr?1.covalent bonds2.hydrogen bonds3.ionic forces4.dipole forces5.dispersion forcescorrectExplanation:You might have thought that dipole forceswas right.The fact is that the dipole be-tween iodine and bromine is incredibly weak- too weak to account for the fact that thiscompound is a liquid. Another FACT is thatdispersion forces are the dominant forces heredue to the SIZE of these atoms and hencemolecule.Just know that not ALL dipoleforces are bigger than any set of dispersionforces.Size matters, and dispersion forceswin out here.00410.0 pointsWhich of the following structures representsa possible hydrogen bond?1.FH· · ·Fcorrect2.CH· · ·O3.ClH· · ·Cl
baum (awb464) – H11: Solids and Liquids – mccord – (50970)24.BrH· · ·BrExplanation:H-bonds are a special case of very strongdipole-dipole interactions.They only occurwhen H is bonded to small, highly electroneg-ative atoms – F, O or N only.