Jennifer Claps
Scientific Concept: Iron ions as an element that is present in all of the solutions throughout the experiment. Depending on what chemical the iron ions react with will depend on the color change of the water.
Materials:
Ferric Chloride
Ammonium Thiocyanate
Tannic Acid
Oxalic Acid
3 eyedroppers
Stirring rod
3- 50 mL Beakers
Distilled Water
1- 250 mL Beaker
Graduated Cylinder
six - 1000 mL or 800 mL Beakers
Rubber Gloves
Directions:
******Make stock solutions of the chemical for multiple shows by doing steps 1-4 below.
1. Measure out 10.8 g of Ferric Chloride. Place it in one of the 50 mL beakers. Add 10 mL of distilled water. Measure the total solution and if it is not 20 mL, add distilled water until the solution is 20 mL. Make sure the Ferric Chloride is dissolved.
2. Measure out 2.2 g of Ammonium Thiocyanate. Place it in one of the 50 mL beakers. Add 5 mL of distilled water. Measure the total solution and if it is not 10 mL, add distilled water until the solution is 10 mL. Make sure the Ammonium Thiocyanate is dissolved.
3. Measure out 10 g of Tannic Acid. Place it in one of the 50 mL beakers. Add 10 mL of distilled water. Stir the solution until the Tannic Acid is dissolved.
4. Measure out 10 g of Oxalic Acid. Place it in the 250 mL beakers. Add 50 mL of distilled water. Measure the total solution and if it is not 100 mL, add distilled water until the solution is 100 mL. Stir the solutions vigorously for several minutes until the oxalic acid is dissolved. This will take some time.
******The above 4 solutions should be put in small bottles for future use as you will be only using small amounts for each demo.
5. Line up five 800 mL beakers in a row. Label them 1-5.
6. Place 25 drops of the ferric chloride solution into beaker #1.
7. Place 2 drops of the ammonium thiocyanate solution into beaker #2 and 10 drops into beaker #3.
8. Place 12 drops of the tannic acid solution into beaker #4.
9. Measure 20 mL of the oxalic acid solution with a graduated cylinder and place it in beaker #5.
10. Fill your last beaker with 600 mL of water, label it beaker #6.
11. Pour the solution in beaker #6 into beaker #1. Swirl the solutions and it should be a yellow like color, call it lemonade.
12. Pour the solution from beaker #1 into beaker #2. The solution formed should be an orange-red color, call it iced-tea.
13. Pour the solution from beaker #2 into beaker #3. The solution formed should be dark red, call it red wine.
14. Pour the solution from beaker #3 into beaker #4. The solution formed should be blue-black like grape juice.
15. Pour the solution from beaker #4 into beaker #5. The solution formed should be yellow, we're now back to lemonade.
Introduction: Have you ever been unsure of what you want to drink? Well, this cool experiment allows you to make several different drinks, but the trick is you use one drink to make another.
Explanation: The element iron is the dominant element throughout the experiment and is present as the plus 3 ion. Each beaker is filled with a different chemical solution which will react with the iron ions to form a new compound with a different color. The idea of switching partners is present when each reaction takes place. The first reaction between iron and water simply dilutes the ferric chloride and makes the normally orange solution into a dilute yellow.
The second reaction shows what happens when a low concentration of ammonium thiocyanate and ferric chloride will create iron thiocyanate complex. The third beaker illustrates the reaction between a higher concentration of ammonium thiocyanate and the iron ions present from the second beaker.
The fourth beaker demonstrates the reaction between tannic acid and iron ions. The result is the compound iron (III) tannate. At the end, the yellow solution is created when the compound iron (III) oxalate is formed. In each of the above two reactions, the first iron compound is destroyed and changed into a new more stable compound. In each case the compounds switch partners.
One reaction is used to show the switch partners concept:
Beaker #3: FeCl3 + 3 KSCN ---> Fe(SCN)3 + 3 KCl.
Safety: Use normal precautions when handling the chemicals.
Disposal: The final products may be poured down the drain.
Reference: Summerlin, L, Ealy, J, Chemical Demonstrations, American Chemical Society, 1985, p. 143