CH 102 1st Edition Lecture 2Outline of Current Lecture II. Non-Bonding Cohesive EnergiesIII. Ion–Dipole AttractionIV. Intermolecular Forcesa. Dispersion forcesb. Polar moleculesc. Hydrogen bondsd. Ion–dipole attractionsV. Attractive Forces and SolubilityVI. Immiscible LiquidsVII. Surface TensionVIII. ViscosityIX. Capillary ActionCurrent LectureX. Non-bonding Cohesive Energies:a. Dispersion forces – induced dipoleb. Dipole attraction – dipole-dipolec. Ion-dipoled. Hydrogen bondingXI. Ion–Dipole Attractiona. In a mixture, ions from an ionic compound are attracted to the dipole of polar molecules.b. The strength of the ion–dipole attraction is one of the main factors that determine the solubility of ionic compounds in water.These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.XII. Intermolecular Forcesa. Dispersion forces have the following characteristics:i. They are the weakest of the intermolecular attractions.ii. They are present in all molecules and atoms.iii. Their magnitude increases with molar mass.b. Polar moleculesi. dipole attractive forces.c. Hydrogen bonds arei. a type of dipole–dipole interaction;ii. the strongest of the intermolecular attractive forces a pure substance can have;iii. present when a molecule has H directly bonded to either O, N, or F atoms. (The only example of H bonded to F is HF).d. Ion–dipole attractions arei. present in mixtures of ionic compounds with polar molecules;ii. the strong intermolecular attractions;iii. especially important in aqueous solutions of ionic compounds.XIII. Attractive Forces and Solubilitya. Solubility depends, in part, on the attractive forces of the solute and solvent molecules.i. Like dissolves like.ii. Miscible liquids will always dissolve in each other.b. Polar substances dissolve in polar solvents.c. Nonpolar molecules dissolve in nonpolar solvents.d. Many molecules have both hydrophilic and hydrophobic parts.i. Solubility in water becomes a competition between the attraction of the polar groups for the water and the attraction of the nonpolar groups for their own kind.XIV.Immiscible Liquidsa. Pentane, C5H12, is a nonpolar molecule, and water is a polar molecule.b. The attractive forces between the water molecules are much stronger than the attractions of the water molecules for the pentane molecules.c. The result is that the liquids are immiscible -(incapable of becoming homogenous).XV. Surface Tensiona. Surface tension is a property of liquids that results from the tendency of liquids to minimize their surface area.b. To minimize their surface area, liquids form drops that are spherical.i. As long as there is no gravityc. Ex: Fly fishing ;The unseen force that lets a mayfly dance on the surface of the waterd. The layer of molecules on the surface behaves differently than that on the interior, because the cohesive forces on the surface molecules have a net pull into the liquid interior.e. The surface layer acts like an elastic skin, allowing you to “float” a paper clip eventhough steel is denser than water.f. Because they have fewer neighbors to attract them, thesurface molecules are lessstable than those in the interior.i. They have a higher potential energy.g. The surface tension of a liquid is the energy required to increase the surface area a given amount.i. Surface tension ofH2O = 72.8 mJ/m2 (At room temperature)ii. Surface tension ofC6H6 = 28 mJ/m2h. Factors Affecting Surface Tension:i. The stronger the intermolecular attractive forces, the higher the surface tension will be.ii. Raising the temperature of a liquid reduces its surface tension.1. Raising the temperature of the liquid increases the average kineticenergy of the molecules.2. The increased molecular motion makes it easier to stretch the surface.XVI. Viscositya. The resistance of a liquid to flow.i. Ex: syrup has a high viscosity because it does not flow easily.b. Units:i. 1 poise = 1 P = 1 g/cm s (Ofen given in centipoises, cP)∙ii. H2O = 1 cP at room temperaturec. Larger intermolecular attractions = larger viscosityd. Factors Affecting Viscosity:i. The stronger the intermolecular attractive forces, the higher the liquid’s viscosity will be.ii. The more spherical the molecular shape, the lower the viscosity will be.1. Molecules roll more easily.2. Less surface-to-surface contact lowers attractions.iii. Raising the temperature of a liquid reduces its viscosity.1. Raising the temperature of the liquid increases the average kineticenergy of the molecules.2. The increased molecular motion makes it easier to overcome the intermolecular attractions and flow.XVII.Capillary Actiona. the ability of a liquid to flow up a thin tube against the influence of gravity.i. The narrower the tube, the higher the liquid rises.b. Capillary action is the result of two forces—cohesive and adhesive—working in conjunction. i. Cohesive forces hold the liquid molecules together.ii. Adhesive forces attract the outer liquid molecules to the tube’s surface.c. The adhesive forces pull the surface liquid up the side of the tube, and the cohesive forces pull at the interior liquid.d. The liquid rises up the tube until the force of gravity counteracts the capillary action forces.e. The narrower the tube diameter, the higher the liquid will rise up the