Osmosis and Colloids

Osmosis and Colloids
Osmotic Pressure
Another colligative property
A solution and a pure solvent are
separated by a semipermeable
- membrane allows solvent but not
solute to pass through
As time passes, the volume of the
solution increases while the volume of
the solvent decreases
- stops when equilibrium is reached
Flow of solvent through the
semipermeable membrane is called
Since the liquid levels are different at
equilibrium, there is a different fluid
The excess pressure on the solution is
called osmotic pressure
The greater the concentration of the
solution the greater the osmotic pressure
Reverse Osmosis
Small particles can be suspended, without
dissolving, in a liquid – don’t settle to the
Can detect these particles by shining an
beam of light through the suspension
If the beam is visible from the side, then
there are suspended particles scattering
Called the Tyndall Effect
Suspension of tiny particles is called
a colloid
Suspended particles range in size
from 1 to 1000nm
They are classified according to the
states of the dispersed phase and
the dispersing medium
Pg. 550
If heat or an electrolyte is added to
a colloid, particles may clump
together (called coagulation) and
fall to the bottom