2 The reaction between thiosulfate ions and hydrogen ions produces a precipitate of sulfur. When the concentration of hydrogen ions, [H+(aq)], is kept constant, the rate is proportional to one of the following: • the concentration of thiosulfate ions, [S2O32-(aq)] • the square of the concentration of thiosulfate ions, [S2O32-(aq)]2. You will determine which relationship is correct by mixing solutions of sodium thiosulfate and sulfuric acid. You will measure the time taken for a fixed amount of sulfur to be precipitated. Throughout these experiments care must be taken to avoid inhaling any SO2 gas that is produced. It is very important that as soon as each experiment is complete, the contents of the beaker are emptied into the quenching bath and the beaker is rinsed thoroughly. FA 3 is 1.00 mol dm⁻³ sulfuric acid, H2SO4· FA 4 is 0.100 moldm⁻³ sodium thiosulfate, Na2S2O3.