FACTORS THAT AFFECT THE RATE OF DISSOLVING
Solubility is determined by the intermolecular attractions between solvent and solute
particles. The rate of dissolving, or how quickly a solute dissolves in a solvent, increases
with three main factors:



High temperatures – solid solutes have a higher kinetic energy for collisions in solvent
molecules.
Agitating a mixture by stirring or shaking the container
Decreasing the size of the particles
A solute will only dissolve in a solvent if the intermolecular forces surrounding the
molecules are greater than the intramolecular forces within the molecule.
See Figure at top of page P. 383
Polar substances dissolve in polar solvents, and non-polar substances dissolve in non-polar
solvents.
Dipole – Dipole Attractions:
It is the attraction between the opposite charges on two different polar molecules,
intermolecular attraction. In water, this attraction is called hydrogen-bonding, and occurs
between the oxygen atom on one molecule and the hydrogen atoms on a nearby molecule.
Ion – Dipole Attractions:
When an ionic compound comes in contact with water, the negative end of the dipole on
some water molecules attracts the cations on the surface of the ionic crystal. The positive
end of the water dipole attracts the anions. Generally, an ionic compound will dissolve in a
polar solvent since the ion-dipole attractions replace the ionic bonds between the cations
and anions in an ionic compound.
A hydrated ion is one in which the ions are surrounded by water.
When the hydrated ions can move through a solution and conduct electricity, the aqueous
solution is called an electrolyte.
NaCl(s) —> Na+(aq) + Cl-(aq)
CaCl2(s) —>
Al(NO3)3(s) —>