3Phase ChangesPhase changes, trans-formations from one phase to another, occur when energy (usually in the form of heat) is added or removed.3 PhasesH2O (l) H2O (g)Gas phase - steamLiquid phase - waterH2O (s) H2O (l)Solid phase - iceH2O (s) H2O (g)
6Phase Diagram of WaterA phase diagram summarizes the conditions at which a substance exists as a solid, liquid, or gas.
7Physical Characteristics of Gases Gases assume the volume and shape of their containers.Gases are the most compressible state of matter.Gases will mix evenly and completely when confined to the same container.Gases have much lower densities than liquids and solids.
8Elements that exist as gases at 25 0C and 1 atmosphere
13Boyle’s Law P a 1/V P x V = constant P1 x V1 = P2 x V2 Constant temperatureConstant amount of gasP x V = constantP1 x V1 = P2 x V2
14A sample of chlorine gas occupies a volume of 946 mL at a pressure of 726 mmHg. What is the pressure of the gas (in mmHg) if the volume is reduced at constant temperature to 154 mL?
15Scuba Diving and the Gas Laws Chemistry in Action:Scuba Diving and the Gas LawsDepth (ft)Pressure (atm)1332663PV
16Charles’ & Gay-Lussac’s Law As T increasesV increases
17V a T V = constant x T V1/T1 = V2/T2 Variation of gas volume with temperature at constant pressure.V a TTemperature must bein KelvinV = constant x TV1/T1 = V2/T2T (K) = t (0C)
18A sample of carbon monoxide gas occupies 3. 20 L at 125 0C A sample of carbon monoxide gas occupies 3.20 L at 125 0C. At what temperature will the gas occupy a volume of 1.54 L if the pressure remains constant?
19Avogadro’s Law V a number of moles (n) V = constant x n V1/n1 = V2/n2 Constant temperatureConstant pressureV a number of moles (n)V = constant x nV1/n1 = V2/n2
20Ammonia burns in oxygen to form nitric oxide (NO) and water vapor Ammonia burns in oxygen to form nitric oxide (NO) and water vapor. How many volumes of NO are obtained from one volume of ammonia at the same temperature and pressure?
21Ideal Gas Equation Boyle’s law: V a (at constant n and T) 1 P Charles’ law: V a T (at constant n and P)Avogadro’s law: V a n (at constant P and T)V anTPV = constant x = RnTPR is the gas constantPV = nRT
22PV = nRT PV R = nT (1 atm)(22.4L) = (1 mol)(273.15 K) The conditions 0 0C and 1 atm are called standard temperature and pressure (STP).Experiments show that at STP, 1 mole of an ideal gas occupies 22.4 L.PV = nRTR =PVnT=(1 atm)(22.4L)(1 mol)( K)R = L • atm / (mol • K)
23What is the volume (in liters) occupied by 49.8 g of HCl at STP?
24d is the density of the gas in g/L Density (d) Calculationsd =mVPMRTm is the mass of the gas in gM is the molar mass of the gasPV = nRT= RTMPM = RT= dRTMolar Mass (M ) of a Gaseous SubstancedRTPM =d is the density of the gas in g/L
25C6H12O6 (s) + 6O2 (g) 6CO2 (g) + 6H2O (l) Gas StoichiometryWhat is the volume of CO2 produced at 370 C and 1.00 atm when 5.60 g of glucose are used up in the reaction:C6H12O6 (s) + 6O2 (g) CO2 (g) + 6H2O (l)
26Strong intermolecular forces LiquidsProperties of LiquidsSurface tension is the amount of energy required to stretch or increase the surface of a liquid by a unit area.Strong intermolecular forcesHigh surface tension
27Cohesion is the intermolecular attraction between like molecules Adhesion is an attraction between unlike moleculesAdhesionWhen adhesion is greater than cohesion, the liquid rises in the capillary tube.When cohesion is greater than adhesion, a depression of the liquid in the capillary tube.Cohesionwatermercury
28Viscosity is a measure of a fluid’s resistance to flow. Strong intermolecular forcesHigh viscosity
29Unit cells in 3 dimensions SolidsA crystalline solid possesses rigid and long-range order. In a crystalline solid, atoms, molecules or ions occupy specific (predictable) positions.An amorphous solid does not possess a well-defined arrangement and long-range molecular order.A unit cell is the basic repeating structural unit of a crystalline solid.latticepointUnit CellUnit cells in 3 dimensions
39Extra distance =BC + CD =2d sinq= nl(Bragg Equation)
40X rays of wavelength nm are diffracted from a crystal at an angle of Assuming that n = 1, what is the distance (in pm) between layers in the crystal?
41Types of Crystals Ionic Crystals Lattice points occupied by cations and anionsHeld together by electrostatic attractionHard, brittle, high melting pointPoor conductor of heat and electricityCsClZnSCaF2
42Types of Crystals Covalent Crystals Lattice points occupied by atoms Held together by covalent bondsHard, high melting pointPoor conductor of heat and electricitycarbonatomsdiamondgraphite
43Types of Crystals Molecular Crystals Lattice points occupied by moleculesHeld together by intermolecular forcesSoft, low melting pointPoor conductor of heat and electricity
44Cross Section of a Metallic Crystal Types of CrystalsMetallic CrystalsLattice points occupied by metal atomsHeld together by metallic bondsSoft to hard, low to high melting pointGood conductors of heat and electricityCross Section of a Metallic Crystalnucleus &inner shell e-mobile “sea”of e-