The Formations of Solutions
Objectives:
1. Explain the process by which solutions form.
2. Give the definition of solubility and explain how it is
affected by various factors.
Key
Terms:
solvation
hydration solubility
Notes:
(15-3)
At
some point you may have heard the phrase "like dissolves like" (polar
dissolves polar and non-polar dissolves non-polar). To understand this
phenomena you must consider the intermolecular forces at work in a
solution. If the intermolecular forces present in the solution are compatible
with the solvent, the solvent is considered soluble.
 | Solvation
is the term given to the interaction between solvent and solute. |
 | If
the solvent is water the reaction is called hydration - water is the most
common polar solvent |

(w3.rz-berlin.mpg.de/~mwolf/newfemtos/ eldyn/solvation.gif)

(omega.dawsoncollege.qc.ca/ ray/chemistry/nacl3.gif)
The
solubility is the amount of solute that can dissolve in a solution at given
conditions. It depends on several conditions and is expressed in grams of
solute per 100grams of solvent.
 | Temperature
 | Solubility of a gas is decreased with an increase in temperature
 | due to an increase in the kinetic energy of the molecules |
|
 | Solubility of a solid is usually increased with an increase in
temperature (endothermic reactions)
 | exception: |
 | Exothermic - increasing temperature decreases solubility |
 | an increase temperature has no effect on solubility when there is
no temperature change for the solution |
|
|
 | Pressure
 | Solubility of a gas is increased with and increase in pressure |
 | Solubility of of a solid is usually unaffected by pressure |
|
Factors affecting the rate of dissolving
 | Surface area
 | The greater the surface area the greater the rate of dissolving |
 | Breaking the solute into smaller pieces increases the surface area |
|
 | Stirring - increases the rate of dissolving by bringing solvent in contact
with solute |
 | Temperature - increases rate by increasing the kinetic energy of the
solvent |
|