Diffusion

Experiment 1: Diffusion through a liquid

Materials

Red dye (M.W.= 496 g/mol)

Blue dye (M.W.= 793 g/mol)

4 Micropipettes

Corn syrup

1 Petri dish (top and bottom)

Ruler

Watch*

Viscous liquid from your

cupboard*

* You must provide

IMPORTANT NOTES:

Perform the experiment on only one side of the plate at a time.

Once the syrup has reached the edges of the dish, place the drop of dye on the plate right away.

If you wait too long, the syrup will develop a "skin" and the dyes will not be able to penetrate into the solution.

Procedure

Separate the bottom and top of the petri dish. Place the two dishes over a ruler, making sure that you can read the markings on the ruler through the dish.

Fill the two halves of the petri dish with corn syrup until the entire bottom surface is covered.

Using a micropipette, place a single drop of blue dye in the middle of the petri dish lid. Note where the drop fell on the ruler.

Measure the diameter of the dye (the distance it has traveled) every 10 seconds for a total of 2 minutes. Record your measurements in the following tables (Tables 1, 2, and 3) and graph your results (distance traveled on the y axis, time on the x axis).

Repeat this process using the red dye in the bottom half of the petri dish.

After you have recorded your results, clean out the petri dish halves.

Choose one other liquid from your cupboard and repeat steps 2-5 using your chosen material in place of the corn syrup.

Record your results in Table 1.

Table 1: Diffusion Through Liquids

Corn Syrup Material:______________

Time (sec) Blue Dye Red Dye Blue Dye Red Dye

10

20

30

40

50

60

70

80

90

100

110

120

Table 2: Diffusion Rate of Dyes in Corn Syrup

Dye Name Molecular Weight Total Distance Traveled (mm) Speed of Diffusion (mm/hr)*

Blue Dye

Red Dye...