Simple experiment - Blue flame

Good day, curious chemists! Today we will conduct a simple but spectacular experiment.

Its essence is that the hydrogen released during the reaction burns with a blue flame.


So we need:

  • Hydrochloric acid concentration of 15%;

  • Copper sulfate;

  • Aluminium foil.

The experiment will be conducted in a glass jar.

As a vessel, you can take a Petri dish or a beaker. I do not recommend using the flask, since it will be difficult for oxygen to flow inside due to the narrow neck of the latter.


Before conducting this experiment, I strongly recommend that you familiarize yourself with the safety precautions when working with acids.

Pour in a jar a teaspoon of vitriol and pour 40 ml of acid. The solution turns green due to the formation of the complex copper ion tetrachlorocuprate [CuCl4] 2-.

Now it remains to add aluminum foil. It is covered with an oxide film, but the resulting complex quickly destroys it. Then part of the aluminum reacts with acid, the equation of this reaction:

As can be seen from the reaction, hydrogen is released.

The rest of the aluminum interacts with the complex, displacing copper from it:

Reactions proceed quickly, with the release of a large amount of heat.

The hydrogen released burns well in air, let's set it on fire.

A narrow flame flow is associated with the characteristics of the neck of the can, and the copper ions that are present in the solution give it a saturated blue color.

Let's do the same experiment, but in a different bowl:

When all aluminum has reacted, the solution becomes gray with spots of reduced copper on the surface. It should be diluted with plenty of water and drained into the sewer.

At the bottom there is sediment:

It should also be disposed of, since after trying to filter, a light brown precipitate remained on the filter, and it cannot be called copper.


And on this, this article came to an end. This experience can be demonstrated in chemistry classes at school. Good luck to everyone in the repetition!