iron (III) chloride + sodium thiosulfate - write the half reactions and be ionic equation iron (III) chloride + sodium thiosulfate - write the half reactions and be ionic equation iron (III) chloride + sodium thiosulfate - write the half reactions and be ionic equation Solution reaction, complete molecular equation, 2FeCl3 + 2Na2S2O3 --> 2FeCl2 + Na2S4O6 + 2NaCl half reactions, Fe3+ + e- --> Fe2+ 2S2O3^2- --> S4O6^2- + 2e- net-ionic equation, 2Fe3+ + 2S2O4^2- --> 2Fe2+ + S4O6^2- .