3: Osmosis

Question 1

• movement of H2O across the CM in response to the difference in the electrochemical potential of H2O

Answer 1

osmosis

Question 2

driving force behind osmosis

Answer 2

difference in solute concentrations in both sides of the CM

Question 3

factor affecting osmosis

Answer 3

molarity of solutes or # of particles per unit volume of fluid (CONCENTRATION)

!!! Size ( and mass) of the solute particles DOES NOT influence osmosis because solvent ang nagmomove across the membrane

Question 4

when does net flow of water ceases

Answer 4

when the solute concentration is equalized on both sides of the CM (state of equilibrium)

Question 5

the unit of measurement of solute concentration in terms of number of dissolved particles in a volume of fluid or solution

Answer 5

osmolarity (moles/L)

Question 6

concentration of solute in terms of: # of particles

Answer 6

osmoles

Question 7

how many osmoles is 1 mole NaCl? 1 mole CaCl2?

Answer 7

2 osmoles (1 Na particle, 1 Ca particle)

3 osmoles (1 Ca particle, 2 Cl particles)

Question 8

osmotic flow depends on the __________ of particles, not on the _______ of the particles

Answer 8

concentration (particle per volume), size

!!! watch out for dissociating substances like (NaCl as they often result to higher concentrations or particles per volume of solvent)

!!! see diagrams as this can be tricky

Question 9

• pressure generated when H2O diffuses/moves across the membrane
• pressure required to stop osmosis completely
• pressure in the compartment where H2O flowing is equivalent to the osmotic pressure

Answer 9

osmolarity pressure

Question 10

formula for osmotic pressure

Answer 10

Van Hoff’s Law

factors involved:
- # of dissociated particles
- molar gas constant
- absolute or thermodynamic temperature (K)
- molal concentration of a solute

Question 11

osmolarity of a solution relative to the blood
plasma osmolarity

Answer 11

tonicity

Question 12

the blood plasma osmolarity

Answer 12

0.3 osm/L or 300 mosm/L

Question 13

3 types of solution

Answer 13

isotonic - solution with equal solute concentration
hypertonic - solution with high solute concentration
hypotonic - solution with low solute concentration

!!! always put “relative to ‘solution’” when talking about the type of solution

e.g., Blood is isotonic with respect to the cytoplasm.

see module for diagrams