Lecture 3 Flashcards
What is diffusion?
The spontaneous process in which material flows from a region of high concentration to low concentration.
Give Fick’s law, giving the rate of diffusion
D = Diffusion constant
Δc/Δx = ‘Concentration gradient’
The diffusion constant (D) is strongly dependent on…
Temperature
As temp. increases, so does the diffusion.
Diffusion constant formula
k = Boltzmann Constant
f = Friction Constant
Give the formula for Stokes’ law
(Calculate Friction Constant)
f = 6πRη
The diffusion constant for gases in air are usually…
Inversely proportional to the square root of the molecular mass.
(As D decreases, m increases)
Give Van’t Hoff Law
Can be used to calculate osmotic pressure
Isotonic Solution
Where osmotic pressure is equal to the reference osmotic pressure
E.g Blood
Hypotonic Solution
Where osmotic pressure is less than the reference osmotic pressure
Hypertonic solution
Where osmotic pressure is more than the reference osmotic pressure
Which only type of solution should be used for infusions?
Isotonic
Which piece of apparatus can be used to measure osmotic pressure?
Pfeffer type osmometer
Which formula can indirecty be used to calculate osmotic pressure?
Formula to calculate the rate of passive diffusion.
Aeff = Effective cross section of the pores
Δc = Concentration difference between the sides of the membrane
w = membrane thickness
Formula to calculate permeability.
