Unit 9.3 Solutions Solubility
Teacher: Dr. Van Der Sluys
Objectives
• General properties of solutions
• Dissolution reactions
Vocabulary
• Solution - a mixture of a solute and a
solvent
• Solute - a minor component of a
solution.
• Solvent - the major component of a
solution
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Types of Solutions
• Solid solutions - alloys
• Liquid solutions - aqueous solutions
• Gaseous solutions - air
Types of Solutions
• Saturated
• Unsaturated
• Super-saturated
Solubility
• The solubility of a solute in a solvent is
determined by the similarity of the
intermolecular forces.
• “Like dissolves like”
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Temperature and Solubility
• The solubility of
solids increases
with increasing
temperature
• The solubility of
gases tends to
decrease with
increasing
temperature
Solubility Questions
• How many grams of
potassium nitrate
can be dissolved in
100 g of water at
50°C?
• How many grams of
sodium nitrate can
be dissolved in 250
g of water at 25°C?
Dissolution reactions
• When molecular species dissolve in
aqueous solution the molecular nature
of the compound is usually maintained.
C6H12O6 (s) --> C6H12O6 (aq)
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Dissolution reactions
When soluble ionic compounds
dissolve in aqueous solution, the
compound dissociates into its
component ions to produce electrolytes.
NaCl (s) --> Na+ (aq) + Cl- (aq)
Fe(NO3)3 (s) --> Fe3+ (aq) + 3 NO3- (aq)
Measuring Solubility
• The solubility of a compound is often
measured based on the grams of solute that
will dissolve in 100 g of water.
• A compound that will dissolve greater than 1
g of solute per 100 g of water is considered
soluble.
• A compound that dissolves less than 1 g of
solute per 100 g of water is considered
insoluble.
Solubility Rules
• Ions that are generally soluble have
low charges - Nitrates, acetates,
chloride, ammonium, chlorate
• Combining ions with high charges
generally results in insoluble
compounds, i.e Fe2O3
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Solubility Rules
Soluble or Insoluble
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•
•
•
•
•
•
CoS
CaCl2
PbCl2
CaSO4
AgCl
NaOH
Zn(NO3)2
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