1. What are the differences between osmosis and diffusion?
What regulates diffusion and osmosis?
What is the difference between osmolarity and osmolality?
Iso-osmotic, hyper-osmotic and hypo-osmotic
Isotonic, hypertonic and hypotonic?
Be able to do a calculations of solutions (A vs. B):
Molarity, millimolarity, osmolarity, milliosmolarity, water movement
Which solution is: Isotonic, hypertonic and hypotonic?

2. MOLARITY VS MOLALITY
One mole of a solute (MW) dissolved and made up in 1 liter of solvent (1000ml) is a 1M (one molar solution)
One mole of a solute (MW) dissolved in 1 kilogram of solvent (1000g) is a 1m (one molal solution)

3. Assumed equal in all our examples!!!
MOLARITY/MOLALITY
1M = One molar
1m = One molal
1M = 1000mM (millimoles)
1m = 1000mm (millimolals)
Assumed equal in all our examples!!!

4. OSMOTIC PRESSURE
The greater or larger the [solute] of a solution, the greater the osmotic pressure
Osmotic pressure is measured is measured as Osmolarity or Osmolality
(remember equal for us because everything dissolves completely in our solvent (water)

5. OSMOTIC PRESSURE UNITS
1 Osm = 1 osmole
1 Osm = 1000 mOsm (milliosmoles)
Same units used for Osmolality and Osmolarity!!!

6. OSMOLARITY/OSMOLALITY
Depends on the ratio of solute to solvent
The higher the [solute] the
higher the osmotic pressure
BUT
MAJOR DIFFERENCES BETWEEN
SALTS AND SUGARS!!

7. SUGARS (glucose, sucrose etc.) Do NOT ionize (dissociate) when they
are dissolved in water!!
IM glucose > = 1Osm
(placed in H20)

8. SUGARS (glucose, sucrose etc.) Do NOT ionize when they
are dissolved in water!!
IM glucose > = 1Osm
(placed in H20)
SALTS (NaCl, CaCl2 etc.) DO ionize or
dissociate!!
IM NaCl > 1 Osm Na+ plus 1 Osm Cl-
(each exert own osmotic pressure) = 2 Osm

10. OSMOSIS
Osmosis is the movement of water (solvent) across a semi-permeable membrane from a region of high solvent concentration [low solute] to a region of low solvent [high solute].

11. “osmotically active solute”
OSMOSIS
Water is “pulled” across a semi-permeable membrane to the side that has the highest osmotic pressure or is the most
“osmotically active solute”

12. Effects of Solutions of Varying Tonicity
Isotonic – solutions with the same solute concentration to each other
Hypertonic – solution having greater solute concentration to the other
Hypotonic – solution having lesser solute concentration to the other