Concentration vs Solubility

Therese Donatello              Archbishop Weber H. S.
                               5252 W. Palmer St.
                               Chicago IL 60639
                               (312) 637-7500
          
Objectives:

1. The student will be able to distinguish between concentration and solubility.
2. The student will be able to tell which solution is more concentrated.

Materials Needed:

Bingo chips              Petri dishes            beans
bottles                  eye droppers            food color
water                    table salt              talcum powder
hot plate                wax paper               spoons

Strategy:

1. Ask the students to count the number of Bingo chips in each of the Petri 
   dishes.  They will see that one has more chips than the other.  Explain that 
   the one that has more chips is said to be more concentrated.  Repeat using 
   dishes containing various amount of beans.  Have the students rank the 
   containers from the highest to the lowest concentration. 
2. Have the students fill a bottle half way with water.  Add table salt (one 
   spoonful at a time while stirring) and have them describe what happens as 
   each spoonful is added until no more dissolves.  Then have them do the same 
   thing using talcum powder.  Explain that the table salt when it dissolves is 
   said to be soluble while the talcum powder which does not dissolve is said to 
   be insoluble.  Ask the students to predict what will happen if you use hot 
   water instead of room temperature water.  Then have them repeat the 
   demonstration using the hot water. 
3. Have the students place one drop of food color on a piece of wax paper and 
   then add nine drops of water to the drop of food color.  On a piece of paper 
   have the students draw ten circles and label the first one with the number 
   one.  Ask the students to take one drop from #1 and place it on another spot 
   on the wax paper along with nine drops of water.  Ask the students what part 
   of this solution is from the spot numbered one. Explain that one part is from 
   #1 so one out of ten drops is from #1. Have the students label the second 
   circle 1/10.  Have them repeat this procedure for the remaining eight 
   circles. 
  
Performance Assessment:

1. Students in the lower grades will be able to explain concentration by 
   counting the amount of a substance in a given amount of space.  They will be 
   able to tell the difference between concentration and solubility by seeing if 
   the substance will dissolve in water or not. 
2. Students in the middle grades will be able to distinguish between 
   concentration and solubility when conditions such a temperature change. 
3. Students in the upper grades will be able to tell concentration in a 
   mathematical way as part of a whole.