Dispersement of Particles: Diffusion and Osmosis

Marge Rockwood                 Horace Greeley
                               832 W. Sheridan
                               Chicago IL 60613
                               (312)534-5800

Objectives: 

 For elementary grades, adaptable for Kindergarten through eight.
 Students will be able to describe the many ways in which particles move and 
 transfer from one source to other areas. 
   
Materials Needed:
 
A: vanilla extract, balloon, eye dropper, empty box (shoe box) perfume or 
   ammonia, fresh popcorn in a paper bag (smelly things) 

B: food coloring, water (hot/cold), transparent cups, overhead projector, 
   worksheets 

C: cooked rice kept moist (undercooked, sticky), liquid starch, newspaper, 
   Ziploc bags, worksheets 

D: corn syrup, salt, water, cup, dialysis tubing

Strategy:

A: Demonstrate to the class:  place a few drops of vanilla extract into a 
   balloon (careful not to drip on outside of balloon) knot balloon closed and 
   place into the empty box (prove the box is empty and doesn't smell).  Set 
   aside and work on something else.  At end of class, open the box and smell 
   (heavy odor of vanilla).  Have the class examine and explain. 

   Instruct the students to close their eyes and raise their hand the moment 
   they smell an odor.  Spray perfume or open ammonia in front of the room; 
   record time and number of students that raise their hand.  Discuss what was 
   happening and why.  Try other areas and odors in room.  Place a fresh paper 
   bag of popcorn in the room and notice how many students say they smell it. 

B: Opt. (Have a glass pie pan filled with water on an overhead and place drops 
   of food coloring into water and observe.)  Each student needs a cup of hot
   and a cup of cold water along with food coloring.  Instruct them to place 
   one drop into the cold water and time it until it is uniformly colored
   and do the same for hot water.  Do worksheet and discuss results.  Chart 
   results on chalkboard.  

C: Have students in groups with 4-6 members.  Each group has rice in a Ziploc 
   bag and some newspaper.  Cover the floor or desk that they will be working 
   over.  One student will stick their hand in the liquid starch and then in the 
   bag of rice.  With the rice covered, hand shake hands with each remaining 
   member. They can record data and compare with other groups.  First child will 
   have most rice and the last child to shake hands with the rice person will 
   have the least.  (another way) Similar to a chain link, the rice person will 
   shake hands with one person and that person shakes hands with the next one in 
   line until everyone has given a hand shake. 

D: Have students in groups with 4-6 members.  Each group needs salt, corn syrup, 
   water, dialysis tubing and two cups.  A salt water solution and the corn 
   syrup are placed in their own dialysis tubing and then placed in each cup.  
   Fill each cup almost full with water.  Let it sit and check it daily for 
   results.  Students should see that water is moving from the clear water into 
   the tubing which has either salt water or corn syrup.  Record and discuss.  

Performance Assessment:

I would expect that all the students would be able to successfully complete
and perform the experiments.
I would assess their learning from: observation, discussion, participation
and completion of work sheets.

WORKSHEETS
A: Do you think the vanilla will escape?_________________
   How will it escape?_________________________________________________
   Did the vanilla escape?____________
   Give an explanation for the results.________________________________
   ____________________________________________________________________
B: What will happen when the coloring enters the water?________________
   ____________________________________________________________________
   Will the two cups get the same results?_____________________________
   If not, why?________________________________________________________
   Basis for your reasoning.___________________________________________
   ____________________________________________________________________
   start time for cold:____________ end time for cold:_________________
   start time for hot:_____________ end time for hot:__________________
   Based on your results what was happening and why did it turn out that
   way?________________________________________________________________
   ____________________________________________________________________
C: What is going to happen to the rice when you shake hands?___________
   Will there be a difference between the first and last, why?_________
   ____________________________________________________________________
   Where and how did the rice travel during the experiment?____________
   ____________________________________________________________________
   Explain.____________________________________________________________
   Results       amount of rice on hand      amount of rice dropped
   FIRST PERSON  ______________________      ______________________
   SECOND PERSON ______________________      ______________________
   THIRD PERSON  ______________________      ______________________
   FOURTH PERSON ______________________      ______________________
D: What happened inside the dialysis tube with corn syrup?____________________
   What happened inside the dialysis tube with salt water?____________________
   What happened inside both of the cups?_____________________________________
   Explanation:_______________________________________________________________
   
Conclusions:

Students will find out that particles disperse themselves through diffusion and 
osmosis.  Students will find out that particle movement is affected by movement, 
temperature and concentration.  The movement of particles from greatest 
concentration to lowest concentration is diffusion.  Osmosis is the movement of 
water through a semi-permeable membrane.