How Strong Is The Solution?

Ernestine C. Davis             Horace Mann Elementary School
                               8050 S. Chappel Ave
                               Chicago IL 60617
                               (312) 535-6640

Objectives:

   The 2nd and 3rd Grade students will:
 - Follow directions and procedures in the science laboratory.
 - Make a mixture of food coloring and water and then determine which 
   solution is stronger, using bleach to remove the color.
 - Use bleach to remove the color from and paint designs on construction
   paper.
 - Make sugar solutions and determine the sweetest of these by taste.

Materials Needed:

  - Bleach (Hazards: eye, skin, respiratory irritant, and poisonous) 
  - Water
  - Clear Plastic Cups
  - Construction Paper
  - Eyedropper
  - Food Coloring
  - Paper Towels
  - Coffee Stirrers
  - Newspaper
  - Baby Food Jars
  - Q-Tips

Strategy:

    The teacher will demonstrate making a mixture of food color and water. The 
    teacher will ask students questions such as:  What happen to the water when 
    I add one drop of food color?  What do you see when I add two drops?  Does 
    the amount of water change?  What happened to the strength of the solution?, 
    etc.  During the discussion the teacher will bring in definitions of 
    solution and strength of solution. 

A.  Before starting this lab students must be reminded of precautions.  You have 
    seen the action of bleach on colors.  When you use bleach in the laundry, 
    you must be careful not to use it on colored clothes.  Why?  What could 
    happen if you did use it by accident?  You will be able to answer this 
    question from the results of this experiment.  The action of bleach can be 
    shown using the water solutions of different food coloring, as well as 
    various other colored substances.  The teacher will monitor students for 
    safety and correct use of all materials. 

Activity I:

    Students Making Mystery Food Color and Water Solution The teacher will 
    demonstrate adding bleach to food coloring. 

A.  Divide students into groups of six.  Assign each group one food color:  red, 
    blue, green, yellow, orange, and purple.  Record all of your answers in the 
    Results and Observations Section of your worksheet. 

B.  Each student in the group has a cup of water and add one to six drops of the 
    assigned food color.  They will write their names on the label on the cup. 

C.  The student will write the number of drops used on an index card, keeping 
    the number of drops used a secret. 
 
D.  The group now arranges their six cups in order by depth of color (still not 
    having revealed number of drops of color used).  Record this order. 

E.  Which cup in their series do they predict will need the most bleach? 
    Students test this by adding bleach and counting drops.  Record drops/cup, 
    and compare the number of drops to the order in which they put the cups.  
    Finally they will reveal the number of mystery drops. 

F.  Each student will graph (bar graph) group results: The number drops of food 
    color (horizontal) vs number of drops bleach (vertical). 

Activity II:

    Bleach Art
    Each student will make a design by using a Q-tip to apply bleach to 
    different colors of construction paper. 
                   
Performance Assessment:

    The student will be able to tell how many drops of bleach are required
    to clear solutions with different amounts of food color.  They will
    be able to define concentration and solution.  They will be able to make 
    a bar graph.
 
Conclusion:

    The removal of color is dependent upon the strength of the color and the 
    amount of bleach used. 
     
References:  

Kitchen Chemistry, Carson-Dellosa Publisher
Mr. Wizard's Supermarket Science, Book Lab