1. Factors Affecting Diffusion
Lesson 26 - Factors Affecting Diffusion
Factors Affecting Diffusion
What is Diffusion?
How does Diffusion Work?
What Affects Diffusion?

2. Where does Diffusion Occur?
Diffusion is something that occurs in fluids (both liquids and gasses) because the particles are allowed to move freely around one and other (mix)
Turn to page 129 in the Science Focus 8 textbook please

3. The Big Idea!!!
Diffusion is the gradual movement of solute particles from an area of High Concentration to an area of Low Concentration
Solvent particles
Solute particles

4. What is Diffusion?
Diffusion is the gradual movement of solute particles from an area of High Concentration to an area of Low Concentration
The movement of solute particles continues until the concentration reaches an equilibrium
Define the term Equilibrium

5. Equilibrium
Equilibrium is the state in which a balance has been reached and “things” have become balanced… an equal distribution of the solute particles within the solvent.
Equilibrium comes from the root word “EQUAL”

6. Steps in Diffusion
At first there is a high concentration gradient which causes the particles to gradually mix and move from the area of high concentration to an area of low concentration
The particles continue to move and mix until they are evenly dispersed throughout the container
Diffusion
Equilibrium

7. When does Diffusion Occur?
Diffusion takes place when there is a difference in concentration levels for the solute particles
One area of a container has a lot of solute particles, the rest of the container has very few (no) solute particles
This is called a Concentration Gradient
Define the term Concentration Gradient

8. Concentration Gradient
Concentration Gradient means a separation or difference in the amounts of particles gathered in one section of a container
High Concentration Gradient
Large difference in amounts
Low Concentration Gradient
Small difference in amounts

9. Diffusion Demo Set up a small chart like this to do the demo
Type of Diffusion
Room Temp Water
Hot Water
Cold Water
Manual Stirring
Time (s)

10. Demo Time!!!
Lets look a diffusion demo and relate it to the particle model of matter
We will diffuse KMnO4 (potassium permanganate) into a water solution and time how long it takes to diffuse
As you watch these demos takes place, make a note of what is happening visually, as well as what you think is occurring to the particles in the solution

11. In which situation did the KMnO4 diffuse the fastest / slowest WHY?
What did we see?
Type of Diffusion
Room Temp Water
Hot Water
Cold Water
Manual Stirring
Time (s)
In which situation did the KMnO4 diffuse the fastest / slowest
WHY?

12. Factors Affecting Diffusion?
The Three Factors Affecting Diffusion are:
SIZE of PIECES
HEAT
STIRRING

13. Factor of Diffusion? SMALLER SIZE of PIECE:
By having smaller pieces of solute, it allows for a larger surface area for the solvent particles to interact and mix with. The more mixing of particles means the substance reaches equilibrium faster

14. Surface Area Ratio

15. Factors Affecting Diffusion?
STIRRING:
By stirring the solution, you cause the particles of the solute and solvent to mix faster and reach equilibrium much quicker

16. Factors Affecting Diffusion?
HEAT:
By increasing the heat energy of the solution the particles within that solution to move faster. This causes the solute to spread out and reach equilibrium more quickly within the solvent

17. Demo Time!!!
Lets look at another demonstration where we change the temperature of the solvent before adding a solute

18. Your Assignment
You are being given a short assignment on factors affecting diffusion
You may start to work on the sheet now and we will go over the answers together in the next class