Chemistry

Chemistry

Problem

In an experiment to find the purity of a sample of magnesium iodide, MgI2MgI_2, 1.50 g of the impure solid was dissolved in water and made up to a volume of 250 cm3250\text{ cm}^3. A 25.00 cm325.00\text{ cm}^3 portion of the solution was transferred into a beaker and an excess of potassium iodate(V) solution was added, which liberated iodine. The equation for the reaction is as follows: KIO3(aq)+5I−(aq)+6H+→3I2(aq)+3H2O(l)KIO_3(aq) + 5I^-(aq) + 6H^+ \rightarrow 3I_2(aq) + 3H_2O(l) The amount of iodine liberated was determined by titrating the mixture with 0.050 mol dm−30.050\text{ mol dm}^{-3} sodium thiosulfate solution. The average titre was 23.40 cm323.40\text{ cm}^3. The equation for the reaction of iodine with thiosulfate ions is as follows: 2S2O32−(aq)+I2(aq)→S4O62−(aq)+2I−(aq)2S_2O_3^{2-}(aq) + I_2(aq) \rightarrow S_4O_6^{2-}(aq) + 2I^-(aq) Calculate the purity of the magnesium iodide by following steps a–g.

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