"Acid Cloud" experiment
How to obtain phosphoric acid using red phosphorus
In this stunning experiment, there’ll be a lot of smoke, a mysterious disappearance, and a solution will change color.
Reagents and equipment:
- red phosphorus;
- a 2-l flask;
- spirit burner;
- litmus solution;
- distilled water;
- spoon for burning;
Pour distilled water into a 2-l flask and add the litmus solution. In the spoon for burning light the red phosphorus in the spirit burner flame and lower into the flask. Seal with a cork. The color of the litmus changes to red, and the white smoke gradually disappears.
When the phosphorus burns, phosphorus(V) oxide forms.
Pred + О₂ → Р₂О₅
As phosphorus(V) oxide is an acidic oxide, when it interacts with water, phosphoric acid forms.
Р₂О₅ + 3Н₂О →2Н₃РО₄
Litmus is an acid-base indicator, and depending on the pH of the medium has three colors: red (an acid medium), purple (a neutral medium), and blue (an alkaline medium).
Phosphoric acid changes the color of the litmus indicator from purple to red.
Work in protective gloves and glasses and in a well-ventilated room. Observe safety rules with combustible substances.
Warning! Substances of this experiment are toxic and highly dangerous for your health. Do not try this at home. Only under professional supervision.