The reaction between hydrogen peroxide, H2O2(aq), and iodide ions, I-(aq), takes place in acidic conditions. H2O2(aq) + 2I-(aq) + 2H+(aq) → I₂(aq) + 2H2O(I) reaction 1 The rate of this reaction can be found by measuring the time taken for a given amount of iodine, I₂(aq), to form. This is done by adding a known amount of thiosulfate ions, S2O32-(aq), and allowing the I2(aq) formed in reaction 1 to react with the S2O32-(aq). I2(aq) + 2S2O32-(aq) → 2I-(aq) + S₄O₆²¯(aq) reaction 2 After the S2O32-(aq) ions have all reacted in reaction 2, any further I2(aq) formed in reaction 1 can be detected using an indicator. A student carried out a series of experiments to determine the order of reaction with respect to the concentration of I-(aq) ions in reaction 1. The student prepared the following solutions. solution A 0.100 mol dm⁻³ KI(aq) solution B 0.0500 mol dm⁻³ Na2S2O3(aq) The student also had access to the following chemicals. solution C 0.100 mol dm⁻³ H2O2(aq) 0.2 mol dm⁻³ H₂SO₄(aq) distilled water a suitable indicator