Chemical cocktail

Three layer liquid turns brown-yellow, blue and red.

Scientific name: Different substances dissolve in suitable solvents.

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Chemical cocktail

by ChemToddler

Safety

Wear eye protection and gloves. Work in a well-ventilated room or outdoors.

Always follow general safety recommendations. Please note that conducting chemistry experiments you must comply with the relevant legal procedures in your country.

Reaction formula

2R-(C=O)-CH3 + 2OH- +3 I2 → 2R–(C=O)–O- + 2CHI3

Step-by-step instruction

  1. Prepare two volumetric cylinders.
  2. Pour about 50 ml of chloroform to each cylinder.
  3. Pour about 50 ml of water to each cylinder as a second layer. Add the water carefully avoiding mixing.
  4. The last layer is ethyl acetate. Pour about 50 ml of ethyl acetate on top of the liquid in the cylinders. As a result you should obtain a three-layer liquid that consists of three immiscible solvents.
  5. Take two beakers filled separately with a few grams of iodine and a few grams of copper sulfate.
  6. Place some iodine on the deflagration spoon. Put it into the first cylinder. Move it up and down to let the iodine distribute between the phases.
  7. Repeat the procedure with copper sulfate and the second cylinder.
  8. Observe the color changes.

Scientific background

This experiment is based on different solubility of substances in different solvents. The ability of a solvent to dissolve different substances depends on such factors as hydrogen bounding, dipole moments and polarizability. The general concept, which describes the ability of a substance to form a solution in a defined solvent, can be formulated as “like dissolves like”.

Cooper sulfate is an ionic compound and a polar solvent is the best to dissolve it. Water is a polar solvent and is suitable for this purpose. The organic solvents are not polar and could not dissolve copper sulfate. The iodine molecule has nonionic structure. It is insoluble in water but when it is mixed with nonpolar chloroform iodine molecules experience the London dispersion forces. Iodine molecules are separated from each other in the original crystal structure by nonpolar solvent molecules. The color of the obtained solution is caused by the molecular form of iodine. It is violet similar to color of iodine vapor. In ethyl acetate iodine change its color due to the iodoform reaction:

2R-(C=O)-CH3 + 2OH- +3 I2 → 2R–(C=O)–O- + 2CHI3

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Published on 23 April 2015

  • Fire
  • Heating with fire
  • Explosion
  • Poisoned gas
  • Organic
  • Electricity
  • Solution
  • Oxidation reduction
  • Color change
  • Precipitate
  • Gassing
  • Catalyst