Chapter 11 - Summary General Chemistry PDF

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Intermolecular Forces and the Liquid State OWL ● Gases consist of molecules whose separation is much larger than the molecules themselves. ● The molecules of a gas are in continuous, random, and rapid motion. ● The average kinetic energy of gas molecules is determined by the gas temperature, and all gas molecules at the same temperature, regardless of mass, have the same average kinetic energy. ● Gas molecules collide with one another and with the walls of their container, but they do so without loss of energy in "perfectly elastic" collisions. *The molecules, atoms, and ions that make up liquids and solids are in constant motion Condensed phases~ the particles are packed in close proximity to one another Gas -> Liquid -> Solid increase in packness

Intermolecular forces (IMFs)~ the forces that exist between the individual particles that make up solids, liquids, and gases *Physical state of a substance is controlled by pressure, temperature and IMFs *IMFs vs chemical bonds in a molecule Chemical bonds hold bonded atoms together in a single molecule IMFs are forces that exist between molecules, atoms, or ions that make up a particular substance

Fusion~ physical state change from solid to liquid Vaporization~ the physical state change from liquid to gas *Both fusion and vaporization are examples of phase changes that require the input of energy Condensation~ physical state change from gas to liquid

Results in the release of energy

Enthalpy of vaporization (the heat of vaporization)~ the energy required to convert one mole of a liquid to vapor at a given temperature *Converting a liquid to vapor involves overcoming the forces between the molecules in the liquid *The magnitude of the enthalpy of vaporization is a direct indication of the strength of the IMFs in the liquid As strength of IMF in liquids increases, enthalpy of vaporization increases Vapor pressure~ pressure of vapor Increases as molecules at the surface of the liquid escape into the gas phase Dynamic equilibrium~ when rates of vaporization and condensation become equal Equilibrium vapor pressure~ the pressure of the vapor over a liquid when a dynamic equilibrium is reached at a given temperature Step 1: Convert the volume of water to the moles of water present that can potentially evaporate Remember to multiply L by 1000 and the appropriate gram for mol of ___ Step 2: Dimensions given by 1003 over 1000 mL Step 3: PV=nRT Step 2 is V Step 1 is n T is in Kelvin Make sure pressure is in the appropriate unit Answer found * 760 mn Step 4: Compare the gotten ideal value to the original If the found value is greater, all the water will NOT evaporate *Vapor pressure is highly dependent on temperature As temperature increases, more molecules have the minimum kinetic energy needed for the gas phase The number of molecules in the gas phase increases Vapor pressure increases *Stronger IMFs equals less vapor escape *Type of intermolecular forces increases with larger number of electrons: induced dipole-

induced dipole *The greater the molar mass, the greater the IMFs Boiling point~ temperature at which the vapor pressure of the liquid is equal to the external pressure Normal boiling point~ temperature when the vapor pressure of a liquid is equal to 1 atm 8As the strength of the IMFs in a series of liquids increases, the boiling point of the liquid increases...