Hands-on Activity:
Real or Phony?
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Background
In these activities you will be working with chemical and physical properties of aspirin or ASA, salicylic acid or SA, other nonaspirin pain relievers, iron and selected iron compounds, and a number of white powders and substances commonly found in many kitchens in the past hundred years. After performing a number of observations and tests, your team will be paired with another team in developing a mini-mystery or mini-history story to be shared with the class. |
Purpose and Introduction |
The activity Making Aspirin calls for 1% iron(III) chloride (also known as ferric chloride). Do you remember it? When the golden brown FeCl3 is added to salicylic acid, a deep purple color is immediately produced. This is due to the formation of special chemical bonds between the Fe+3 ion and a hydroxy group on the salicylic acid. It turns out that one Fe+3 ion (which gives the solution its golden brown color before it's exposed to SA) will combine with the hydroxy groups of six different SA molecules. This new and larger ion is called a complex ion. This new complex ion produces the purple color.
Fe+3 ion complexed by salicylic acid molecules.
Another two tips that might prove useful to you and your group: (1) aspirin or ASA will very slowly react with water to form salicylic acid (SA) and acetic acid; (2) acetaminophen has an important similarity to SA. Okay, now let's get on with the action.
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This activity was developed by Professor Johnnie-Marie Whitfield, Millsaps College.