This suggest that dissociation of FeCl3 is 100 % to form 4 ions (1Fe+3Cl). Other dissociation also may be possible like FeCl3---->(FeCl2) + Cl- FeCl3---->(FeCl)2+ + 2Cl- so number of ions is averaged considering dissociation constants which is 3.4 Solution This suggest that dissociation of FeCl3 is 100 % to form 4 ions (1Fe+3Cl). Other dissociation also may be possible like FeCl3---->(FeCl2) + Cl- FeCl3---->(FeCl)2+ + 2Cl- so number of ions is averaged considering dissociation constants which is 3.4.