Ozone: the guardian of our planet
Oxygen is essential to life as we know it – but can it be poisonous?
We've put together some ozone layers for you. What to do next – see in this experiment!
Attention! All experiments are performed by professionals. Do not attempt.
- flask with ozone;
- rubber stopper;
- solutions of iron(II) sulfate and potassium thiocyanate;
- porcelain bowl;
- potassium iodide solution;
- filter paper.
A flask is filled with ozone using an ozonizer and closed with a stopper. When a strip of filter paper is moistened with a solution of potassium iodide and put in the flask of ozone, the paper turns brown. When the walls of another flask are coated with a solution of iron(II) sulfate and potassium thiocyanate, and the flask is filled with ozone using an ozonizer, the flask turns red.
Ozone is a colorless gas with oxidizing properties. It can be produced in a laboratory via an electric discharge, and it forms in the atmosphere after lightning strikes: its low concentration in the air creates the familiar fresh smell after a thunderstorm.
3 O₂ → 2 O₃
Ozone easily converts iodide ions into molecular iodine.
2KI + O₃ + H₂O → I₂ + 2KOH + O₂
And it converts iron(II) to iron(III), which forms a red compound Fe(SCN)₃ with potassium thiocyanate:
3FeSO₄ + 6KSCN + O₃ + H₂O → 2Fe(SCN)₃ + 3K₂SO4 + Fe(OH)₂ + O₂
Ozone is poisonous, but it can be used to purify water, and it helps make life on Earth possible: a layer of this gas in the stratosphere protects us from harmful solar radiation.
Safe experiments await you in the MEL Chemistry subscription!