1. What factors effect diffusion ?

2. By the end of this lesson I will be able to:
use the particle model to explain diffusion  
describe evidence for diffusion

3. Experiment: You are going to investigate the effect of temperature on diffusion
Prediction
1) What do you expect to see when you add the purple potassium permanganate crystals to water?
  2) What do you expect to happen when the water temperature increases?

4. Potassium permanganate Square glass beakers hot water ice bath
Equipment:
Safety
Potassium permanganate Square
glass beakers
hot water
ice bath
tweezers
plastic straws
thermometer
spatula
stopwatch
Wear eye protection.
Take care handling hot equipment and water.
Avoid getting potassium permanganate on your skin.
Mop up spills using a dry paper towel
Wash your hands at the end of the lesson.

5. Method
1 )Draw a results table. You will be measuring the time it takes for all the water in your beaker to go purple in colour. 2)Place 200 cm3 water from the tap into a 250 ml beaker. 3)Record the temperature of the water. 4)Select a crystal of potassium permanganate using tweezers and use the plastic straw to carefully place the crystal into the water, at the bottom of the beaker. (Do not release it from the tweezers until the straw is on the bottom of the beaker.) 5)Quickly remove the straw from the beaker. 6)Start the stopwatch. 7)Record the time it takes for the water to become purple throughout. 8) Repeat this procedure with water at different temperature (50 °C, 70 °C, 90 °C) and water cooled in an ice bath. Try to select similar sized crystals each time.

6. Diffusion is the ___________ mixing and moving of _________
Diffusion is the ___________ mixing and moving of _________. Particles have ________energy at higher temperatures so diffusion is _________. Diffusion cannot happen in _________ but ___________diffuse quickly because particles are far apart and don’t _________into each other. Small particles diffuse __________than big particles.

7. Diffusion is the random mixing and moving of particles
Diffusion is the random mixing and moving of particles. Particles have more energy at higher temperatures so diffusion is faster. Diffusion cannot happen in solids but gases diffuse quickly because particles are far apart and don’t collide into each other. Small particles diffuse quicker than big particles.

8. In this lesson I have learnt:
Particles move around randomly in gases and liquids because they have energy   
the higher the temperature, the faster diffusion happens  
big, heavy particles diffuse slower than smaller, light particles  
gases diffuse quicker then liquids
diffusion does not occur in solids.

9. Homework
Write a short paragraph explaining why hot water is best for making cups of tea.