Chapter #11: Liquids, Solids, and Intermolecular Forces11.2 Solids, Liquids, and Gases: A Molecular Comparison- Density of solid and liquid is much greater than density of gas.- Solid and liquid are more similar in molar volume than gas.- Most solids are slightly denser than their liquid state but water is less dense as a solid than liquid.- Thermal energy in liquids allow to overcome attraction so molecules can move past one another.- Molecules in solids stay in the same position and vibrate.- Liquid assume the shape of it’s container and cannot be easily compressed.- Gas can be compressed to smaller volume.- Solids have fixed shape and volume.- Solids can be crystalline in a regular ordered structure or amorphous where they have no long-range order.Changes Between States- Change the state of substance by changing temperature or pressure.- Increase in pressure changes substance to denser state. For instance, gas to liquid.11.3 Intermolecular Forces- Structure of the particles in substance determine strength of intermolecular forces.- Strong intermolecular forces result in liquid and solid while weak intermolecular forces result in gas.- Intermolecular forces is an interaction between charges.- Potential energy of particles decrease with increase in magnitude of charge and decrease in distance.- Molecules are attracted to one another because potential energy decrease as they get closer.- Strongest intermolecular force is much weaker than bonding forces.- Intermolecular forces are interactions of smaller charges and greater distance.Dispersion Force- Dispersion force is the fluctuation of the distribution of electrons in a nonpolar molecule or atom.- Electrons may be unevenly distributed within the particle around the nucleus.- Side with more electrons will take on a slightly negative charge and the other will be slightly positive.- This temporary charge separation is called an instantaneous dipole or temporary dipole.- Positive side of instantaneous dipole will attract the negative side of another instantaneous dipole.- Magnitude of dispersion force rely on how easily electrons can be polarized.- Larger electron clouds are less tightly held by nucleus and thus easier to polarize.- Molar mass can act as a guide to determining strength of dispersion force but factors such as molecular shape need to be taken into consideration as well.- Straight shape of molecules will be more beneficial for interaction than spherical shape because it has a larger area of interaction.Dipole-Dipole Force- Dipole-dipole forces exist in polar molecules where electron rich regions will adopt a negative charge and electron deficient regions adopt a positive charge.- Region may be electron rich because the element is more electronegative than the other components that compose the molecule.- The result is a permanent dipole because unlike dispersion forces where the charge separation may change, the charge separation here is permanent.- Dipole-dipole forces are stronger than dispersion forces.- All molecules, including polar, have dispersion forces but in addition dipole-dipole forces as well.- Polar molecules have higher melting and boiling points than non polar.- Polarity determine miscibility.- Polar liquids mix with polar liquids and is not miscible with nonpolar liquids.Hydrogen Bonding- Hydrogen bonding occurs when hydrogen is bonded to small electronegative atoms such as fluorine, oxygen, or nitrogen.- Difference in electronegativity creates a extremely strong dipole-dipole force giving hydrogen a large partial positive charge and fluorine, oxygen, or nitrogen a large partial negative charge.- Stronger than dipole-dipole forces and dispersion forces.- Positive hydrogen of molecule is attracted to negative F, O, or N of surrounding molecules.- Substance with hydrogen bonding have higher melting point than those without.Ion-Dipole Force- Ion-dipole force occur when ionic compound is mixed with polar compound.- Positive ions of ionic compound interact with negative poles of polar compound and positive poles of polar compound interact with negative ions of ionic compound.- Create aqueous solution where ionic compound dissociate.- Ion-dipole force is the strongest of all intermolecular forces.11.4: Intermolecular Forces in Action: Surface Tension, Viscosity, Capillary ActionSurface Tension- Surface tension is the tendency for liquids to minimize their surface area.- Energy require to increase surface area by a unit amount.- Surface molecules have higher potential energy than those in interior because it has fewer neighbors to interact with. Less stable.- Minimizing surface area tend to resist penetration.- Surface tension decrease with decrease in intermolecular forces.Viscosity- Viscosity is the resistance of liquid to flow.- Measured in unit called poise (P = 1 g/cm*s).- Water at room temperature is 1cP.- Viscosity greater with stronger intermolecular forces because molecules are more attracted to one another.- Viscosity increases with increasing molar mass and length of molecule.- Viscosity decrease as temperature increase.Capillary Action- Capillary action is ability of liquid to flow against gravity..- Capillary action a result of cohesive and adhesive forces.- Cohesive forces is attraction between molecules.- Adhesive forces is attraction between molecule and wall.- Adhesive forces cause liquid to spread out and cohesive forces cause liquid to stay together.- When adhesive forces are greater than cohesive, it draws the molecules up against gravity and cohesive forces pull molecules along.- If adhesive forces are weaker than cohesive, liquid will not rise but will drop..11.5: Vaporization and Vapor PressureProcess of Vaporization- Vaporization is when liquid changes to gas.- Molecules at high end of energy distribution curve can break free and escape and with increasing temperature, more molecules enter the high end of distribution curve.- Surface molecules can break free easier than interior ones.- Both evaporation and condensation occur in a beaker but evaporation is of a greater rate because once molecule escape, it never comes back.- Increase in temperature and surface area increase vaporization.- Vaporization increase when there is a decrease in intermolecular forces.Energetics of Vaporization- Vaporization is an endothermic process where energy is required.- Cooling, sweat requires heat from body to vaporize and thus cools body.- Condensation is an exothermic process where energy is