The Perfume Mystery: Understanding Diffusion

Imagine you're sitting in your classroom when someone sprays perfume at the front of the room. At first, only the people nearby can smell it. A few moments later, students in the middle notice it.

Finally, even the students at the back can smell it! But the perfume didn't have legs. So how did it travel across the room?

Welcome to the fascinating world of diffusion!

What is Diffusion?

Diffusion is the net movement of particles from a region of high concentration to a region of low concentration until they are evenly spread out.

Think of it as particles moving from a crowded place to a less crowded place.

Figure 1: Movement of particles through diffusion.

Why Does Diffusion Happen?

Particles are constantly moving because they have kinetic energy. They move randomly in all directions. When many particles are crowded together, they spread into areas where there are fewer particles until equilibrium is reached.

Concentration Gradient

Imagine a playground with 100 children on one side and only 10 on the other. As they move around, more children naturally move to the less crowded side. This difference in concentration is called the concentration gradient. The steeper the concentration gradient, the faster diffusion occurs.

Factors Affecting Diffusion

1. Concentration Gradient

   
   

The greater the difference in concentration, the faster diffusion occurs. Once particles become evenly

spread, diffusion slows because equilibrium has been reached.

2. Temperature

Higher temperatures give particles more kinetic energy, causing them to move faster and increasing the

rate of diffusion.

3. Surface Area

   
   

A larger surface area allows more particles to diffuse at the same time, increasing the rate of diffusion.

4. Diffusion Distance

   
   

The shorter the distance particles have to travel, the faster diffusion takes place.

Diffusion in Everyday Life

• Perfume spreading through a room

• Tea spreading through hot water

• The smell of food travelling from the kitchen

• Oxygen moving from the lungs into the blood

• Carbon dioxide entering leaves for photosynthesis

Why is Diffusion Important?

• Cells receive oxygen.

• Carbon dioxide leaves cells.

• Plants obtain carbon dioxide for photosynthesis.

• Waste products are removed from cells.

Quick Summary

• Diffusion is the net movement of particles from high to low concentration.

• It continues until equilibrium is reached.

• It does not require energy.

• Higher temperature, steeper concentration gradient, larger surface area and shorter diffusion distance increase the rate.