Chem 104 1st Edition Lecture 1 Outline of Last Lecture I. Outline of Dipole-dipole attractions, Hydrogen bonds, and dispersion forcesII. Overview of solubility, ion-dipole attraction, and introduction to surface tensionOutline of Current Lecture II. Liquids and their properties.A. Definition of surface tensionB. Definition of viscosityC. Definition of meniscusD. Definition of vaporizationIII. Introduction to Vaporization and Condensation.A. The factors that affect vaporization and condensationCurrent LectureLiquids and their properties and structures:I. Surface tension: a property of liquids that results from the tendency of liquids to minimize their surface area.Liquids minimize size by forming spherical drops as long as there is no gravity. The stronger the intermolecular forces, the stronger the surface tension. Cohesive forces on the surface act differently than the interior forces by acting like a skin which allows you to “float” on its surface.Since they have less neighbors to draw in, the surface molecules are less stable than those in the below the surface. These molecules have a higher potential energy.Surface tension of H2O at room temperature = 72.8 mJ/m2Surface tension of C6H6 = 28 mJ/m2i. Example: Water allows a paper clip to float even though the metal in the paper clip isdenser than the water it’s sitting on.ii. Example: Imagine a crowded concert. The people in the center of the crowd are close to their neighbors around them whereas, the people in the front only have to be close to the stage and the people beside them and behind them.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.As the temperature increases, the kinetic energy increases. When the kinetic energy increases itcauses the molecular motion to jump and makes it easier for molecules to stretch to the surface. Thus, raising the temperature of a liquid reduces its surface tensionII. Viscosity: the resistance of a liquid to flow. Unit of measurement:1 Poise = 1 P = 1 g/cm*sThe stronger the intermolecular attractions, then the sturdier the viscosity of the liquid will be. However, the more spherical the molecule is, the lower the viscosity will be. Molecules can roll more easily and obtain less surface area with a rounded surface. Also, the higher the temperature of the liquid, then the lower the viscosity is due to the increase in kinetic energy toovercome the intermolecular forces.i. Example: CH3CH2CH2CH3 and CH3CH2CH3. Which has a higher viscosity?1. CH3CH2CH2CH32. Why? Because of its larger molar mass.ii. Example: CH3CH2OH and CH3CH2CH3. Which has a higher viscosity?1. CH3CH2OH.2. Why? The hydrogen bond makes it stronger as a liquid.III. Meniscus: The curving of the liquid surface in a thin tube is due to the competition between adhesive and cohesive forces. The meniscus of water is concave in a glass tube. This is due to the tube’s adhesion is stronger than the cohesion of itself. The meniscus of mercury is convex in a glass tube. This is due to the tube cohesion for itself is stronger than its adhesion for the glass. Above all, metallic bonds are stronger than intermolecular attractions.Could there be no meniscus?Yes if the adhesion and cohesion forces are the same in the container.IV. Vaporization: If high energy molecules are at the surface they may have enough energy to overcome the attractive forces. As surface area increases the rate of evaporation will increase. The weaker the attractive forces between molecules, the less energy they will need to vaporize. With weaker attractive forces, the net result will be more molecules in the vapor phase, and a liquid that evaporates faster. A liquid that evaporates easily is known as volatile. A liquid that does not evaporate easily is known as nonvolatile.V. Condensation: molecules of vapor will lose energy through molecular collisions and becomecaptured back into a liquid when they collide with the liquid. Some stick and gather to form droplets on surrounding surfaces.i. Example: By boiling H2O, you’re giving energy to molecules so they move and escape through the top of the container they’re being boiled in. After bumping into one another the molecules transfer energy, lose energy, and then come back down.Evaporation and condensation are opposite processes. In an open container vapor molecules spread out faster and towards the surface. The result is that the rate of vaporization is larger than the rate of condensation. Overall there is a loss of liquid. The weaker the attractive forces the less likely the liquid will condense due to the rapid activity of molecules. In a closed container, the vapor does not spread out forever, this is called dynamic equilibrium. When intermolecular forces slow down then the energy drops as well.When the high energy molecules are lost from the liquid, it lowers the average kinetic energy. Energetics of evaporation includes high energy molecules lost from the liquid that then cause the average kinetic energy to decrease. If energy is not drawn back into the liquid then the temperature decreases, therefore explaining that vaporization is an endothermic due to its need for an input of energy in order to influence its intermolecular attractions. Thus, condensation is