lodate ions contain iodine and oxygen. They have the formula $$\(\mathrm{IO}_{x}^{-}\)$$where $$\(x\)$$ is an integer. In this experiment you will determine the value of $$\(x\)$$ in an iodate. You will first react $$\(\mathrm{IO}_{x}{ }^{-}\)$$with an excess of iodide ions, $$\(\mathrm{I}^{-}\)$$, to form iodine, $$\(\mathrm{I}_{2}\)$$. The amount of iodine produced is then determined by titration with thiosulfate ions, $$\(\mathrm{S}_{2} \mathrm{O}_{3}{ }^{2-}\)$$. $$\[ \mathrm{I}_{2}(\mathrm{aq})+2 \mathrm{~S}_{2} \mathrm{O}_{3}{ }^{2-}(\mathrm{aq}) \rightarrow 2 \mathrm{I}^{-}(\mathrm{aq})+\mathrm{S}_{4} \mathrm{O}_{6}{ }^{2-}(\mathrm{aq}) \]$$ FB 2 is $$\(0.100 \mathrm{~mol} \mathrm{dm}^{-3}\)$$ sodium thiosulfate, $$\(\mathrm{Na}_{2} \mathrm{~S}_{2} \mathrm{O}_{3}\)$$. FB 3 is a solution containing $$\(0.0140 \mathrm{moldm}^{-3} \mathrm{IO}_{x}^{-}\)$$ions. FB 4 is dilute sulfuric acid, $$\(\mathrm{H}_{2} \mathrm{SO}_{4}\)$$. FB 5 is $$\(0.500 \mathrm{~mol} \mathrm{dm}^{-3}\)$$ potassium iodide, KI . FB 6 is starch indicator. Calculations (i) Give your answers to (c)(ii), (c)(iii) and (c)(iv) to an appropriate number of significant figures. (ii) Use your answer to (b) and the information given to calculate the amount, in mol, of iodine formed when $$\(25.0 \mathrm{~cm}^{3}\)$$ of FB 3 reacts with $$\(10 \mathrm{~cm}^{3}\)$$ of FB 5 . amount of $$\(\mathrm{I}_{2}=\)$$ .......................... mol (iii) Calculate the amount, in mol, of $$\(\mathrm{IO}_{x}^{-}\)$$ions in $$\(25.0 \mathrm{~cm}^{3}\)$$ of FB 3. $$\[ \text { amount of } \mathrm{IO}_{x}^{-} \text {ions }= \]$$ .......................... mol (iv) An unbalanced equation for the reaction of $$\(\mathrm{IO}_{x}^{-}\)$$ions with iodide ions, $$\(\mathrm{I}^{-}\)$$, and hydrogen ions, $$\(\mathrm{H}^{+}\)$$, is shown. $$\[ \mathrm{IO}_{\ldots}-+\ldots \ldots \ldots \mathrm{I}^{-}+\ldots \ldots \ldots \mathrm{H}^{+} \rightarrow \ldots \ldots \ldots \mathrm{I}_{2}+\ldots \ldots \ldots . \mathrm{H}_{2} \mathrm{O} \]$$ Use the ratio of your answers to (c)(ii) and (c)(iii) to balance this equation and determine the value of $$\(x\)$$. Show your working. ratio $$\(\mathrm{IO}_{x}^{-}: \mathrm{I}_{2}=1:\)$$ .......................... $$\(x=\)$$ ..........................

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