Experiment W33:
Chorine gas has bad smell, it bleaches the red colour of mallow tea

In the  previous experiment particles coloured like rust were formed because part of the chlorine reacted with the metal of the injection needle.
In the following experiment the injection needles will be replaced by the  two pieces of pencil lead.
* Make a concentrated salt solution.
* Boil it with some leaves of dried mallow tea to extract the red colour.
* Connect the pencil leads with a 9-Volt battery.
* Dip them into a vial with red salt solution (photo 1).


Gas bubbles will form at both electrodes.
The red colour disappears around the right (positive) electrode first (photo 2).
The positive electrode smells: Chlorine was formed at this electrode and has bleached the red colour.
Crystal water in salts: red and blue cobalt chloride:  Experiment W34                       home