4 Fe2P + 12FeS2 --> 14FeS + P4S10
Left Side:
20 Iron
4 Phosphorus
24 Sulfur
Right Side:
14 Iron
24 Sulfur
4 Phosphorus
this reaction is not balancable. therfore this reaction does not occur. you cannot balalnce it because everytime you put the sulfurs on the right equalto the sulfurs on the left you make the irons on the left imbalance to the irons on the right. and whenyou try to fix the irons on the left then you mess up the sulfurs on the right and it is a cycle that can not be broken.