Laboratory:  Diffusion of Water with Gummy Worms

 

 

Name __________________________________________

 

Purpose:  To investigate the movement of water into and out of a polymer.  Gummy worms are made of gelatin and sugar. 

 

Background:  Gelatin is a polymer that forms large three dimensional matrices which give structural support to jellies and jams, and lots of other things that you use every day.  What is the independent and dependent variable

 

Hypothesis:  Which substance do you think will diffuse better?  (water or distilled)

 

Materials:

   List all materials.

 

Procedure:

  1. Obtain two plastic cups, two different colored Gummy Bears and two rulers.
  2. On the side of each cup, write your name and class period using a permanent marker.
  3. Label one cup "TAP WATER" and the other "DISTILLED WATER".
  4. Measure your bear (in cm) from top to bottom (length) and from side to side (width) and from front to back (height). Record the centimeters in the data table.  Use decimals.
  5. Place the bears in the cups and cover one with distilled and one with tap water.
  6. Place the cups on the counter away from direct sunlight.  Let them sit overnight.
  7. On the next lab day, gently pour the water over a screen into a sink.  Catch each bear on a separate screen. 
  8. While on the screen, measure the length, width, and height.  Record. Blot the screen dry by placing it on a paper towel.  BE CAREFUL not to break the bears, they are very fragile.
  9. Place the bears back into their correct cups.  Cover the bears with saturated salt solution.  Let them sit overnight.
  10. Find the dimensions of the bears and record.  Calculate the volumes (l x w x h).

Data Table for Dimensions in centimeters: (Use decimal numbers.)

    Gummy Bear in Tap Water 

 

Length

Width

Height

Volume

Before Water (Day 1)

 

 

 

 

After Water (Day 2)

 

 

 

 

After Salt Water (Day 3)

 

 

 

 

 

*  Please also write your data in class data sheet

 

Gummy Bears in Distilled Water

 

Length

Width

Height

Volume

Before Water (Day 1)

 

 

 

 

After Water (Day 2)

 

 

 

 

After Salt Water (Day 3)

 

 

 

 

 

*  Please also write your data in class data sheet

 

Create a graph that shows types of water vs volume of Gummy Bear.  You should have three lines.  Remember to Place your independent variable on the x-axis of your graph and the dependent variable on the y-axis

 

Analysis:  Explain your data.  What does it have to do with diffusion and the cell membrane.

 

Conclusion:

 

Write a lab report for this lab using the scientific method.  Please see lab rubric.