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Ch. 15 - SolutionsCh. 15 - Solutions
I. How Solutions Form Definitions Types of Solutions Dissolving Rate of Dissolving
A. DefinitionsA. Definitions
Solution - Solution - homogeneous mixture
Solvent Solvent - present in greater amount
Solute Solute - substance being dissolved
B. Types of SolutionsB. Types of Solutions
Based on state of solvent. All solid-liquid-gas combos are
possible. EX: dental amalgam (alloy of silver,
mercury, etc.)• liquid solute, solid solvent• solid solution
C. DissolvingC. Dissolving
SolvationSolvation
• occurs at the surface of the solute
• solvent particles surround solute particles (+/- attraction)
• solute particles are pulled into solution
D. Rate of SolutionD. Rate of Solution
Solids dissolve faster...Solids dissolve faster...
• more stirring
• small particle size(increased surface area)
• high temperature
D. Rate of SolutionD. Rate of Solution
Gases dissolve faster...Gases dissolve faster...
• no shaking or stirring
• high pressure
• low temperature
A. ConcentrationA. Concentration
Concentrated solutionConcentrated solution • large amount of solute
Dilute solutionDilute solution • small amount of solute
A. ConcentrationA. Concentration
% by Volume% by Volume• usu. liquid in liquid• EX: 10% juice = 10mL juice + 90mL water
% by Mass% by Mass• usu. solid in liquid• EX: 20% NaCl = 20g NaCl + 80g water
A. ConcentrationA. Concentration
SATURATED SOLUTION
no more solute dissolves
UNSATURATED SOLUTIONmore solute dissolves
SUPERSATURATED SOLUTION
becomes unstable, crystals form
concentration
B. SolubilityB. Solubility
SolubilitySolubility• maximum grams of solute that will
dissolve in 100 g of solvent at a given temperature
• varies with temperature• based on a saturated solution
B. SolubilityB. Solubility
Solubility CurveSolubility Curve• shows the
dependence of solubility on temperature
B. SolubilityB. Solubility
Solids are more soluble at...Solids are more soluble at...• high temperatures.
Gases are more soluble at...Gases are more soluble at...• low temperatures.• high pressures
(Henry’s Law).
Ch. 15 - SolutionsCh. 15 - Solutions
III. Particles in Solution “Like Dissolves Like” Electrolytes Colligative Properties
A. “Like Dissolves Like”A. “Like Dissolves Like”
NONPOLAR
NONPOLAR
POLAR
POLAR
DetergentsDetergents• polar “head” with long nonpolar “tail”• can dissolve both types
B. ElectrolytesB. Electrolytes
ElectrolyteNon-
Electrolyte
solute exists asions only
- +
salt
- +
sugar
solute exists asmolecules
only
- +
acetic acid
WeakElectrolyte
solute exists asions and
molecules
B. ElectrolytesB. Electrolytes
DissociationDissociation• separation of +/-
ions when an ionic compound dissolves in water
B. ElectrolytesB. Electrolytes
IonizationIonization• breaking apart of
polar covalent molecules into ions when dissolving in water
C. Colligative PropertiesC. Colligative Properties
properties of solutions that depend only on solute concentration
Freezing Point DepressionFreezing Point Depression• solutes lower the f.p. of a solvent
Boiling Point ElevationBoiling Point Elevation• solutes raise the b.p. of a solvent
C. Colligative PropertiesC. Colligative Properties
Solute particles “get in the way.”
Boiling Point Elevation