You are required to determine the concentrations of hydrochloric acid and potassium iodate in the diluted solution containing both.
Procedure: A solution containing potassium iodate and hydrochloric acid has already been measured into the volumetric flask provided. Fill the flask to the mark with distilled water using the wash bottle, close it with a stopper and shake it thoroughly. Fill the burette with the standard sodium thiosulphate solution using one of the beakers provided. (The exact concentration of the thiosulphate is given on the label of the bottle.)
(a) First titration Pipette a 10.00 cm3 aliquot (portion) of the solution from the volumetric flask into a glass stoppered conical flask. Dilute it with 10 cm3 of distilled water, add 1 g (a small spatula end-full) of potassium iodide and acidify with 10 cm3 of 10 % sulphuric acid using a measuring cylinder. Titrate immediately the iodine formed with the standard sodium thiosulphate solution until the solution in the flask is pale yellow. Add with a pipette 1 cm3 of starch indicator solution and continue the titration to completion. Repeat the titration twice more and record your readings on the result sheet.
(b) Second titration Pipette a 10.00 cm3 aliquot of the solution into another glass stoppered conical flask, dilute with 10 cm3 of distilled water, add 1 g of solid potassium iodide,and leave to stand for 10 minutes. Then titrate the iodine formed using the standard sodium thiosulphate solution, adding 1 cm3 of starch indicator solution when the mixture is pale yellow. Repeat the titration twice more, recording your readings on the result sheet.
Task: Calculate the concentration of the HCl and the KIO3 in the solution that you prepared by dilution (in mol dm-3).
