Since posting I've thought, maybe the low-magnitude figures
actually pertain to mixtures of P4 and P4O6,
such as would be easy to get if one tried
to make P4O6 by burning P4 with limited oxygen.
P4 melts 44.1 C, boils 280 C.
P4O6 melts 23.8 C, boils 175.4 C.
So NIST's 900 more reported kJ/mol is how far P4(g)
is above P4(s)? It boils at 280 C.
As noted in my other posting,
disprop won't happen if NIST is right, otherwise maybe,
But if some work had been done on P4O6
that bore a large adulteration of P4 --
both colourless, nearly the same mp and bp --
and other, more careful work had used pure P4O6,
all this would be explained.
--- Graham Cowan [Only registered users see links. ] --
fireproof fuel, real-car range, no emissions