“Chlorophyll“ from the “Chemistry of plants“ set
Channel: MEL Chemistry
Date: 19/04/2018

Perform this amazing experiment at home with MEL Science: https://melscience.com/en/experiments/plants-chlorophyll/

Safety
* Put on protective gloves and eyewear.
* Conduct the experiment on the plastic tray.
* Conduct the experiment in a well-ventilated area and away from sources of ignition.

Disposal
* Dispose of solid waste together with household garbage.
* Pour solutions down the sink.
* Wash with an excess of water.

Step-by-step instructions
1. Leaves owe their greenish color to the green pigment chlorophyll. Chlorophyll is almost insoluble in water, but does dissolve in many organic solvents, like ethanol.
2. When enough chlorophyll has dissolved in the ethanol, take two samples of the chlorophyll solution.
3. There is a magnesium ion Mg²⁺ (green one) in each of the chlorophyll molecules, which readily “drops out” in the presence of acid. As a result, pheophytin molecules form, which are much more pale (even yellowish) than the bright-green chlorophyll.
4. Copper ion Cu²⁺ (brown one) from copper salt CuSO₄ readily fits the vacancy the magnesium ion has left in the chlorophyll molecule. The resulting pheophytin copper complex strongly resembles the initial chlorophyll color.
5. It’s difficult to distinguish the chlorophyll sample from the pheophytin copper complex one. But the latter is more stable, so if you leave the samples under a light source, the chlorophyll will soon decompose and lose its color.