2 Solution: Dissolved: Concentration: A solute dissolved in a solvent A homogeneous mixtureDissolved:Broken apart into base particles (ions or molecules)Concentration:The density of dissolved solute in the solvent
4 Dissociation Reactions communicate the process using symbols NaCl Na + ClCaCl2 Ca ClCuSO4 Cu + SO4NH3 NH3CO2 CO2Cu(NO3)2 Cu NO3
5 Like Dissolves LikeMost solutions we discuss and encounter are aqueous (water solvent)Water is polar so it dissolves polar or ionic substances (dipole-dipole or ion-dipole forces in the solution)Oil is nonpolar so it dissolves nonpolar substances (dispersion forces)Dipole-dipole forces will not be broken in order to be replaced by dipole-induced dipole forces or dispersion forcesDispersion forces can not break dipole-dipole forces
6 Like Dissolves Like Hydrophilic Hydrophobic Hydro = waterPhilia = loveHydrophilic = love for waterHydrophobicPhobia = fearHydrophobic = fear of waterMolecules with both a hydrophobic and hydrophilic endSoapCell membranes
7 Energy Lattice Energy: Enthalpy of Hydration: Enthalpy of Solution: Formula:
9 Electrolytes Conduct electricity when dissolved in water Electricity is due to mobile chargesDissolved ionic compounds contain mobile charges and are therefore electrolytesHigher concentration of ions = stronger electrolyte
10 Concentration: density of solute in solvent or solution Molarity = moles solute / Liters solutionMolality = moles solute / kg solventMole fraction = moles solute / moles solution% by mass = grams solute / grams solutionG solute / 100 g H2O (self explanatory)ppm = ? Grams solute / 1,000,000 g solution (parts per million)ppb = ? Grams solute / 1,000,000,000 g solution (parts per billion)
11 Concentration of ions in solution: CaCl2(s) Ca2+(aq) Cl-(aq)If you have a 1.0 M solution of CaCl2,Then you have a 1.0 M solution of Ca2+ ionsAnd you have a 2.0 M solution of Cl- ionsAnd you have a 3.0 M solution of total ions.
12 Concentration of ions: CaCl2 is a stronger electrolyte than NaClBecause it produces more ionsTherefore, if you have equal concentrations of CaCl2 and NaCl, CaCl2 solution will have greater conductivity than NaCl.However, 0.05 M CaCl2 will have less conductivity than 2.0 M NaCl. Why?
13 Dilutions Dilution: If solute isn’t changed molesi = molesf Since moles = (molarity)(Liters)MolarityiLitersi = MolarityfLitersf
14 Types of solutions Typical solutions: solid dissolved in liquid But all phases can be solute or solvent.
15 SolubilitySolubility = maximum possible concentration of dissolved particlesSaturated Solution:Concentration = solubilityUnsaturated Solution:Concentration < solubilitySupersaturated Solution:Concentration > solubilityHow does this occur?
16 SolubilitySolubility = maximum possible concentration of dissolved particlesSolubility of a solid-liquid solution is typically increased with increased temperature. Why?Solubility of a gas-liquid solution is typically decreased with increase temperature. Why?Solubility of a gas-liquid solution is typically increased with increased pressure. Why?
17 Density is based on concentration. Density is also based on temperature.Hotter liquids spread out and therefore have greater volume with equal mass (lower density)D = m / vConcentration could also change with temperature:Any conc calculated using volume is temperature dependent.Any conc calculated using only masses / # particles is not temperature dependent.
18 Colligative Properties Anything that depends on the number of dissolved particles.
19 Colligative Properties Solution’s boiling point increases with greater concentration of particles.Solution’s melting point decreases with greater concentration of particles.Solutions remain liquid through a greater range of temperatures with greater concentration of particles.
25 Colligative Properties: Vapor Pressure A nonvolitile Liquid lowers the vapor pressure of a solvent.Vapor Pressure: pressure over a liquid at gas-liquid phase equilibriumMore solute less vapor pressure less solvent will turn to gasPsolution = Xsolvent Psolvent
30 Side Note:Surface area of liquid is directly proportional to the evaporation rate:Water in a wider beaker will evaporate faster than water in a narrow, tall beaker
31 Osmosis Osmosis: the flow of solvent through a semipermiable membrane from lower concentration to higher concentrationNet Flow of solvent continues until concentration on both sides are equalSimilar to heat transfer between 2 substances of different temperatures
32 Osmotic PressureExcess pressure on a solution with greater volume of solvent (see Figure 11.18)By applying more pressure than the osmotic pressure to a container, you can create “reverse osmosis”Desalinization !!!