química: carbur de fósfor

2·P_{2} + 2·C_{2} + e^{-}  ==> ( =P≡C-C≡P= ) + ( =C=P≡P=C= )


( =P≡C-C≡P= ) + ( =C=P≡P=C= ) + e^{+} ==> 2·P_{2} + 2·C_{2}


entalpia de reacció:
[ 2·P_{2} ] = 20
[ 2·C_{2} ] = 16


[ ( =P≡C-C≡P= ) ] = 18
[ ( =C=P≡P=C= ) ] = 18


20+16 = 18+18 = 36