1. Reaction of Phosphorus with Sodium Hydroxide
A gas is generated which undergoes spontaneous
combustion in the atmosphere

2. Demonstration The reactants were heated together in a Florence flask
The phosphine gas bubbled into the water then broke through the surface
Spontaneous combustion occured when the phosphine emerged into the atmosphere

3. Purpose
To produce an unfamiliar gas related to other more familiar gases
To observe the unique property of spontaneous combustion of this gas

4. Concepts 1. Compounds of Non-Metals with Hydrogen
2. Spontaneous Combustion
3. Disproportionation Reactions

5. 1. Compounds of Non- Metals with Hydrogen
Hydrogen combines with many non-metals to form familiar compounds
BH3 borane, an organic reducing agent
CH4 methane, an organic gas
NH3 ammonia, used as fertilizer
H2O water
H2S hydrogen sulfide, rotten-egg gas

6. 2. Spontaneous Combustion
Flammable substances are simply those that burn in the presence of oxygen with the evolution of heat
There is enough heat in the surroundings to cause spontaneous combustion of some substances
In this demonstration the highly reactive phosphine gas PH3 is generated

7. 3. Disproportionation Reactions
A single reactant ends up in more than one product
Disproportionation of white phosphorus
3NaOH + P H2O NaH2PO PH3
In addition to phophine gas, sodium hypophosphite is formed

8. Conclusions
A disproportionation reaction of phosphorus produced phosphine gas
Phosphine gas underwent spontaneous combustion in the atmosphere
4PH O P4O10 + 6H2O
+ light

9. Comments Phosphine is extremely poisonous
Phosphine occurs naturally from the putrefaction of organic matter containing phosphorus
Will-o-the-Wisp (flammable swamp gas) of Robert Burns is phosphine
Traces of P2H4 initiate combustion
PH3 + 8O H2O P4O10
This demonstration was first performed in 1859 by Gorup-Besanez