Lab 3 271 bot

DIFFUSION

• The movement of particles from a region of higher concentration to a region of lower concentration.

• This process continues until it reaches a state of equilibrium

• Many gases and particles enter the plants body with the help of this process called DIFFUSION.

EXAMPLE –Carbon dioxide enters the leaf through stomata and then passes to other cells in the leaf by diffusion.

However this process is affected by the following

factors.1. Temperature – Increase in

temperature increases the rate of diffusion, this is because the kinetic energy of molecules increases.

2. Mass – Increase in mass of the particles decreases their movement.It is inversely proportional to their molecular weight.

3. Concentration—steeper the concentration differences, quicker is the rate of diffusion.

4. Size – Increase in size of the particle slower is the rate of diffusion.Size is inversely proportional to speed of diffusion.

OBJECTIVE: TO UNDERSTAND THE PROCESS OF DIFFUSION

AIM: To Prove that molecules move from aregion of higher concentration to lower concentration.

• MATERIALS• Petri dishes• Agar• Methylene blue / food colour• Ruler

PROCEDURE• Take a petri dish with agar (chilled,refrigerated

overnight.)• Make a well in the agar.• Carefully, add the dye in the well (around 5-6 drops) • Do not allow the dye to overflow.• Cover the petri dish keeping it horizontal.• Seal it with a paraflim.• This minimizes evaporation.• Refrigerate.• Repeat the experiment with an agar plate and the dye

kept at room temperature.• After it has been sealed.• Leave this dish at room temperature.• Observe both the Petri dishes after 2 hours.

Cold Temperature Room Temperature

Colored Halo Diameter (mm) after 2 hours for plate at: