1. 15-3: The Formation of Solutions

2. A Definition:
Solvation: the interaction between solute and solvent particles
Called hydration when water is the solvent
Involves:
Breaking of attraction among solvent particles
Breaking of attraction among solute particles
Formation of attraction between solvent and solute particles

3. Two more definitions
Endothermic: energy is absorbed (breaking attractions)
Ex: ammomium hydroxide (cold pack)
Exothermic: energy is released (forming attractions)
Ex: sodium hydroxide or sulfuric acid

4. Solubility…
Is the amount of a solute that will dissolve in a specific solvent under existing conditions

5. Factors that influence solubility
Nature of solute and solvent
“like dissolves like”
Polar and ionic – form solution
Non-polar – forms solutions with nonpolar only

6. Factors that influence solubility
Temperature
As the temperature increases, the solubility of a gas in a liquid decreases
The solubility of a solid solute increases as the temperature increases

7. Factors that influence solubility
Pressure
Has little affect on solid and liquid solutes
The solubility of a gas in any solvent is increased as the pressure of the gas over the solvent increases

8. Factors Affecting the Rate of Dissolving
Surface Area:
As the surface area of a solid solute increases, the rate of dissolving increases
Stirring:
Stirring increases the solubility of a solid solute, but not a gas
Temperature:
Increasing the temperature causes a solid solute to dissolve faster, but not a gas