Page 39 - Curriculum Visions Dynamic Book

 Phosphorus reacts with alkalis, which is an unusual property. When white phosphorus is placed in a sodium hydroxide solution, bubbles of gas form. The gas is (poisonous) phosphine gas (PH3) that has a fishy smell. Phosphine gas is prepared in the absence of air
in this apparatus. The phosphine gas contains an impurity, diphosphine (P2H4), which combusts spontaneously in air. This creates the flame you see.
The phosphine gas bubbles catch fire as they burst on the surface of the water. The reaction with the oxygen in the air as it burns forms solid phosphorus oxide and creates white “smoke-rings”.
“Smoke-ring” of phosphorus oxide
combustion: the special case of oxidisation of a substance where a considerable amount of heat and usually light are given out. Combustion is often referred
to as “burning”.
spontaneous combustion: the effect of a very reactive material beginning to oxidise very quickly and bursting into flame.
vapour: the gaseous form of a substance that is normally a liquid. For example, water vapour is the gaseous form of liquid water.
Bubbles of phosphine and diphosphine gas pass through the water and ignite as they burst on reaching the surface.
Concentrated sodium hydroxide
White phosphorus
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