Blue Blob, Black Ink

Archie watched her contemplatively, as If she were a beaker full of chemicals working. 

Adjust your safety glasses comfortably over your eyes, and then add a tablespoon (15 milliliters) of baking soda to a half cup of water (120 milliliters) and stir. Allow the undissolved material to settle to the bottom (this should take about a minute), and then carefully pour off the clear liquid into another glass, leaving the solids. Pour a tablespoon (15 milliliters) of the copper sulfate solution described in the Shopping List and Solutions into the decanted baking soda solution. Beautiful blue flakes should immediately form and settle out of solution. You should also see some bubbles, and the supernatant, the liquid over the blue blob precipitate, should be a pastel blue. The bubbles are from excess acid in the copper solution reacting with the bicarbonate ion. 

The blue blob reaction occurs because the water decanted from the 

With safety glasses securely in place, add a teaspoon (5 milliliters) of hydrogen peroxide to a quarter cup (60 milliliters) of iron acetate solution (see the Shopping List and Solutions ). The solution should turn a nice reddish brown as the ferrous ion becomes the ferric ion. Slowly add a half cup (120 milliliters) of cold, brewed brown tea. You should get a black, mushy precipitate that will eventually settle to the bottom. Historically, this material was used as black ink, and this precipitation reaction was used to produce it. 

To a chemist, saying a solution is clear is not saying the solution is without color. Saying a solution is clear means it has no suspended solids. A precipitation reaction is one in which two clear solutions mix to form a solid in solution. Why should two clear solutions decide to form a solid Consider the following analogous social situation. Two celebrants may come to a party together because it is convenient to share a ride. In the course of an evening, however, they separate and come in contact 

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