Diffusion
Contents of
This Chapter
•Definition and concept of diffusion
•Concept of steady state diffusion and the laws involved
with it
•Methods and procedures of conducting diffusion studies
•Applications of diffusion
Learning
Objectives
• At the end of this lecture, student will be able to
– Explain the concept of diffusion
– Explain steady state and sink condition
– Explain the different laws involved in the process of
diffusion
– Explain the different methods and procedures to conduct
the in vitro diffusion experiment
Diffusion-Definition
and Concept
• Diffusion is defined as a process of mass transfer of
individual molecules of a substance from a region of higher concentration to a
region of lower concentration along a concentration gradient
• The process of diffusion occurs across a barrier
• Barrier is a
region or regions
that offers resistance
to the passage of materials
• The material that undergoes the transport is known as
diffusant or penetrant or permeant
WHAT IS
DIFFUSION?
• Diffusion is a process of migration of solute molecules
from a region of higher concentration to a region of lower concentration and is
brought by random molecular motion.
• Movement from one side of membrane to another side.
• Diffusion is a time dependent process.
• Movement is based on kinetic energy (speed), charge, and
mass of molecule
DIFFUSION
• It is defined as a process of mass transfer of individual
molecules of a substance brought about by random molecular motion and
associated with a driving force such as a concentration gradient.
