Diffusion Lab

Diffusion Lab

Procedure 1:

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 Petri dishes 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 |Corn Syrup |

|Beaker |Absent (Yellow) |Absent (Yellow) |

|Dialysis Tube |Present (Green) |Present (Green) |

Questions:

Which substance crossed the dialysis membrane? What evidence from your results proves this?

What molecules remained inside the dialysis bag?

Of the substances that diffused through the bag, did all of the molecules diffuse out?

Does the dialysis bag or the beaker contain more starch? What about glucose?

Is the bag hypotonic with regards to the Lugol’s solution, or the beaker? What about the starch solution?

What results would you expect if the experiment started with glucose and Lugol’s solution inside of the bag, and starch and water in the beaker? Why?

Draw a diagram of this set up. Use...