Student Handout

<Diffusion of Particles>

Warm-up:

1. What is something that happened to you lately that is evidence that smell travels?

Part 1

Draw a particle diagram showing how the scent moved throughout the room.  Put an “X” to show where the scent started.

Part 2

Question: How does temperature affect the rate of diffusion?

Hypothesis: If we drop food coloring in hot and cold water, it will diffuse faster in ______________ water, because ___________________________.

Draw particle diagrams showing the difference between diffusion in hot water and diffusion in cold water.

Learning Targets: 

1. Students will illustrate how substances diffuse through gas or liquid (fluid) because the particles are moving constantly past each other
2. Students will explain how temperature influences the rate of diffusion
3. Students will understand that due to the collision and random movement of particles, particles will move throughout a substance 

Safety Warning:

Some students are allergic or sensitive to perfumes and certain scents. Be sure to check with your students ahead of time.

Warm-up (8 minutes)

Part 1 (25 minutes)

1. Hand out colored paper 1/pair  (sensor and communicator)
2. Inform students that one will have eyes closed and will be the sensor. The other will be the communicator with the paper. Have student decide which role they will take on.
3. Explain that the sensor will have their eyes closed. As soon as they smell the scent, they should tap the communicator who will then hold up the colored paper clearly so that all of the communicators can see.

Part 2 (15 minutes)

1. Students draw 2 cylinders and label one as cold water and one as warm water.
2. Predict, when food coloring enters the water, which will travel faster and why?
3. Demo and record observations. Take class ideas about why they observed the red mixing faster than the blue- same water and same kind of food coloring… what does temperature affect? mention ENERGY (Kinetic energy of the substance)
4. Now have students draw particle diagram of cold water and warm water (demo how to show energy of particles with arrows or squiggle lines) and particles of food coloring moving through more quickly/slowly based on observations.

• 2 strong scents (perfume, incense, vinegar…)
• Colored paper/scrap paper for each pair of students
• White boards, markers, erasers/per group
• 2 see-through containers (cylinders, beakers large vases…)
• red and blue food coloring (other colors also ok)
• warm and cold water( perhaps hotplate to heat water)
• optional: scaffolds for diagrams