Post on 14-Dec-2015
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SoluteSoluteA solute is the dissolved substance in a solution.
A solvent is the dissolving medium in a solution.
SolvenSolventt
Salt in salt water Sugar in soda drinks
Carbon dioxide in soda drinks
Water in salt water Water in soda
Calculations of Solution Calculations of Solution ConcentrationConcentration
Mass percent - the ratio of mass units of solute to mass units of solution, expressed as a percent
100xsolutionofmass
soluteofmasspercentMass
Calculations of Solution Calculations of Solution ConcentrationConcentration
Mole fraction – the ratio of moles of solute to total moles of solution
BA
AA nn
nAoffractionMole
Calculations of Solution Calculations of Solution ConcentrationConcentration
Molality – moles of solute per kilogram of solvent
solventramloki
solutemolesmMolality
g
Calculations of Solution Calculations of Solution ConcentrationConcentration
Molarity - the ratio of moles of solute to liters of solution
solutionofLiter
soluteofmolesMMolarity
““Like Dissolves Like”Like Dissolves Like”
Fats BenzeneBenzene
SteroidsSteroids HexaneHexane
WaxesWaxes TolueneToluene
Polar and ionic solutes dissolve best in polar solvents
Nonpolar solutes dissolve best in nonpolar solvents
Inorganic Salts WaterWater
SugarsSugars Small alcoholsSmall alcohols
Acetic acidAcetic acid
Solubility TrendsSolubility Trends The solubility of MOST solids The solubility of MOST solids
increases with temperature.increases with temperature. The rate at which solids dissolve The rate at which solids dissolve
increases with increasing surface increases with increasing surface area of the solid.area of the solid.
The solubility of gases decreases The solubility of gases decreases with increases in temperature.with increases in temperature.
The solubility of gases increases The solubility of gases increases with the pressure above the with the pressure above the solution.solution.
Therefore…Therefore…Solids tend to dissolve best when:
o Heatedo Stirredo Ground into small particles
Gases tend to dissolve best when:o The solution is cold
o Pressure is high
Saturation of SolutionsSaturation of Solutions A solution that contains the maximum A solution that contains the maximum
amount of solute that may be dissolved amount of solute that may be dissolved under existing conditions is under existing conditions is saturatedsaturated..
A solution that contains less solute than A solution that contains less solute than a saturated solution under existing a saturated solution under existing conditions is conditions is unsaturatedunsaturated..
A solution that contains more dissolved A solution that contains more dissolved solute than a saturated solution under solute than a saturated solution under the same conditions is the same conditions is supersaturatedsupersaturated..
Henry’s LawHenry’s Law
The concentration of a dissolved gas in a solution is directly proportional to the pressure of the gas above the solution
Applies most accurately for dilute solutions of gases that do not dissociate or react with the solvent
Yes CO2, N2, O2No HCl, HI
S1/P1 = S2/P2
S = solubility in g/L
P = pressure
An electrolyte is:
A substance whose aqueous solution conducts an electric current.
A nonelectrolyte is:
A substance whose aqueous solution does not conduct an electric current.
Definition of Electrolytes and Definition of Electrolytes and NonelectrolytesNonelectrolytes
1.Pure water2.Tap water3.Sugar solution4.Sodium chloride solution5.Hydrochloric acid solution6.Lactic acid solution7.Ethyl alcohol solution8.Pure sodium chloride
Electrolytes?Electrolytes?
ELECTROLYTES: NONELECTROLYTES:
Tap water (weak)
NaCl solution
HCl solution
Lactate solution (weak)
Pure water
Sugar solution
Ethanol solution
Pure NaCl
Answers to Answers to ElectrolytesElectrolytes
Colligative PropertiesColligative Properties
Colligative properties are those that depend on the concentration of particles in a solution, not upon the identity of those properties.
Boiling Point Elevation Freezing Point Depression Osmotic Pressure Vapor Pressure Lowering
Freezing Point DepressionFreezing Point Depression
Each mole of solute particles lowers the freezing point of 1 kilogram of water by 1.86 degrees Celsius.
Kf = 1.86 C kilogram/mol
solutef mKiT
m = molality of the solution
i = van’t Hoffvan’t Hoff factor
Boiling Point ElevationBoiling Point Elevation
Each mole of solute particles raises the boiling point of 1 kilogram of water by 0.51 degrees Celsius.
Kb = 0.51 C kilogram/mol
soluteb mKiT
m = molality of the solution
i = van’t Hoffvan’t Hoff factor
Freezing Point Depression and Boiling Point Elevation Constants,
C/m
Solvent Kf Kb
Acetic acid 3.90 3.07
Benzene 5.12 2.53
Nitrobenzene 8.1 5.24
Phenol 7.27 3.56
Water 1.86 0.512
The van’t Hoff Factor, The van’t Hoff Factor, ii
Electrolytes may have two, three or more times the effect on boiling point, freezing point, and osmotic pressure, depending on its dissociation.
Dissociation Equations and Dissociation Equations and the Determination of the Determination of ii
NaCl(s)
AgNO3(s) MgCl2(s)
Na2SO4(s)
AlCl3(s)
Na+(aq) + Cl-(aq)
Ag+(aq) + NO3-(aq)
Mg2+(aq) + 2 Cl-(aq)
2 Na+(aq) + SO42-
(aq)Al3+(aq) + 3 Cl-(aq)
i = 2
i = 2
i = 3
i = 3
i = 4
Suspensions and Suspensions and ColloidsColloids
Suspensions and colloids are NOT solutions. Suspensions: The particles are so large that they settle out of the solvent if not constantly stirred.
Colloids: The particles intermediate in size between those of a suspension and those of a solution.
Types of ColloidsTypes of Colloids
ExamplesExamples DispersinDispersing g
MediumMedium
Dispersed Dispersed
SubstancSubstancee
Colloid TypeColloid Type
Fog, aerosol spraysFog, aerosol sprays GasGas LiquidLiquid AerosolAerosol
Smoke, airborn germsSmoke, airborn germs GasGas SolidSolid AerosolAerosol
Whipped cream, soap Whipped cream, soap sudssuds
LiquidLiquid GasGas FoamFoam
Milk, mayonnaiseMilk, mayonnaise LiquidLiquid LiquidLiquid EmulsionEmulsion
Paint, clays, gelatinPaint, clays, gelatin LiquidLiquid SolidSolid SolSol
Marshmallow, Marshmallow, StyrofoamStyrofoam
SolidSolid GasGas Solid FoamSolid Foam
Butter, cheeseButter, cheese SolidSolid LiquidLiquid Solid Solid EmulsionEmulsion
Ruby glassRuby glass SolidSolid SolidSolid Solid solSolid sol