Caroline Imreibe

Red, White, and Blue

Science Concept: Adding ammonia to three different chemicals, creates the colors: red, white, and blue, through different chemical reactions.

Materials:

2 eyedroppers of phenolphthalein solution

4 g Epsom salt (MgSO₄)

3.75 ml of crushed copper sulfate crystals

Clear household ammonia

3 flasks

Directions:

1.) Add phenolphthalein to one flask.

2.) Add Epsom Salt in the second flask.

3.) Add the copper sulfate in the third flask.

4.) When ready to present add ammonia to each of the three flasks.

Introduction: Who can tell me the colors of the colors of the Illinois state flag. (probably won't answer) Well what about the U.S. flag? (put ammonia into 3 flasks, while they call the colors out.)

Explanation: Each of the solutions reacted differently to ammonia. In the first flask the phenolphthalein indicator turned red because ammonia is a base. In the second flask, double replacement reaction took place and magnesium hydroxide is a precipitate, making the white color. In the third flask the copper sulfate and ammonia make a deep blue color of a copper-ammonia complex.

Reactions:

NH₃ + H₂O --> NH₄OH which produces a base of hydroxide ions.
OH^- + phenolphthalein ----> pink color

NH₄OH + MgSO₄ ---> Mg(OH)₂ (white precipitate)

Cu ⁺² ions + NH₃ ---> copper - ammonia complex (dark blue)

Safety: Handle wet glassware carefully.

Waste Disposal: Dispose of liquids in sink under plenty of water.

Reference: Summerlin, L, Ealy, J, Chemical Demonstrations, American Chemical Society, 1985, p. 146.