Analysis of sulphur dioxide content in wine.
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Analysis of sulphur dioxide content in wine (c) KCl http://hk.geocities.com/fatherofchemistry Objective To determine the amount of sulphur dioxide, an antioxidant, present in wine by using volumetric analysis. Principle All free SO2 molecules is first convert into SO32- by NaOH solution: SO2 + 2OH- › SO32- + H2O Acidification of the solution liberates all SO2: 2SO32- + 2H+ › 2SO2 + 4H2O which is then titrated with 0.0057M iodine solution in which starch is used as end-point indicator: SO2 + I2 + 2H2O › 2HI + H2SO4 Chemicals white wine (carbonated), 1M NaOH, 2M H2SO4, 0.0057M I2, starch solution Apparatus volumetric apparatus, pipette, measuring cylinder, dropper, white tile Procedure 1.> Find out the volume of wine from the label on the bottle. 2.> Pipette 25cm3 of white wine into a conical flask. 3.> Add about 12cm3 of 1M NaOH and stand for about 15 minutes. 4.> Add about 10cm3 of 2M H2SO4 to the mixture and then...


