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I Lesson 1: The Nature of Solutions
Lesson 1: The Nature of Solutions
Unit 8 Solution ChemistryUnit 8 Solution Chemistry
Characteristics of SolutionsCharacteristics of Solutions
Particles (atoms, ions, molecules) are very small. Particles do not scatter light Liquid solutions are clear Cannot be easily separated by simple physical means. All parts of the solution are uniform or identical
Characteristics of SolutionsCharacteristics of Solutions
A solution has 2 parts A solution has 2 parts
Solvent Solvent - present in greater amount
Solute Solute - substance being dissolved
Solvation Solvation
Solvation – Solvation – the process of dissolving
It is the interaction between solute and solvent particles
Energy is either required or released
Solvation Solvation
A substance that dissolves in a solvent is said to be soluble.A substance that does not dissolve in a solvent is said to be insoluble.For liquid solute-solvent combinations: 2 liquids that are soluble are miscible 2 liquids that are not soluble are immiscible
Solvation Solvation
solute particles are separated and pulled into solution
solute particles are surrounded by solvent particles
Combinations of solute and solvents.
Combinations of solute and solvents.
Solute Solvent Example
solid solid
liquid solid
Solid liquid
liquid liquid
gas liquid
gas gas
Solubility Solubility
Solubility – the ability of one Solubility – the ability of one substance to dissolve in anothersubstance to dissolve in another• maximum grams of solute that will
dissolve in 100 g of solvent at a given temperature
Solubility Solubility
SATURATED SOLUTION
no more solute dissolves
UNSATURATED SOLUTIONmore solute dissolves
SUPERSATURATED SOLUTION
becomes unstable, crystals form
concentration
Solubility Solubility
Solubility CurveSolubility Curve• shows the
dependence of solubility on temperature
Factors Affecting Solubility Factors Affecting Solubility
NONPOLAR
NONPOLAR
POLAR
POLAR
““Like Dissolves Like”Like Dissolves Like”““Like Dissolves Like”Like Dissolves Like”
1. Nature of Solute and Solvent
Factors Affecting SolubilityFactors Affecting Solubility
2. Temperature2. Temperature Solids are more soluble at...Solids are more soluble at...
high temperatures
Gases are more soluble at...Gases are more soluble at...
low temperatures
Factors Affecting SolubilityFactors Affecting Solubility
3. Pressure3. Pressure
Gases are more soluble at...Gases are more soluble at...• high pressures
(Henry’s Law).• EX: nitrogen narcosis,
the “bends,” soda
Factors Affecting SolubilityFactors Affecting Solubility
3. Pressure3. PressureHenry’s Law – At a given temperature, the solubility (S) of a gas in a liquid is directly proportional to the pressure (P) of the gas above the liquid.
S1 = S2
P1 P2
Henry’s Law ProblemHenry’s Law Problem
If 0.85 g of a gas at 4.0 atm of pressure dissolves in 1.0L of water at 25°C, how much will dissolve in 1.0L of water at 1.0 atm of pressure and the same temperature?
S1 = S2
P1 P2
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Factors Affecting the Rate of Dissolving (solvation)
Factors Affecting the Rate of Dissolving (solvation)
Factors Affecting Rate of DissolvingFactors Affecting Rate of Dissolving
1. 1. Surface AreaSurface Area Increasing surface area increases
dissolving. When the area of exposed surface is
increased, more solute particles are subjected to solvation.
Factors Affecting Rate of DissolvingFactors Affecting Rate of Dissolving
2. 2. StirringStirring Stirring increases dissolving. Without stirring, the solvent in contact with
the solute becomes saturated thereby decreasing dissolving.