# 1. A. To determine the concentration of a sodium thiosulfate solution as in this experiment, a...

## Question:

1. A. To determine the concentration of a sodium thiosulfate solution as in this experiment, a student pipetted 25.0 mL of 0.0100 M potassium iodate (KIO3) solution into a 125 mL Erlenmeyer flask. Potassium iodide and sulfuric acid were added as in this experiment. The titration needed 15.21 mL of the sodium thiosulfate to reach the endpoint. What is the concentration of the sodium thiosulfate solution?

B. Into a 125 mL Erlenmeyer flask was added some KI and H2SO4 as described in the procedure section of this experiment. Then 3.0 mL of bleach solution was added to the flask and it was immediately titrated with 0.1261 M sodium thiosulfate solution. It required 41.26 mL of this sodium thiosulfate solution to reach the endpoint of the titration. What is the percentage of NaOCl in the bleach? Assume the density of commercial bleaching solution to be 1.084 g/mL.

## Titration with iodine:

Pharmaceutical products such as vitamins c and hydrogen peroxide serve as one of the primary necessities of humans, however, they imposed danger to health if their shelf life would not be properly and regularly tested. One way to analyze these pharmaceutical products is through titrations with iodine which is a moderately oxidizing agent. Solid iodine is not very soluble in water which is why it is usually prepared in the presence of sodium and potassium iodide. As a result, soluble solutions of iodide salts are produced due to the formation of triiodide ions. However, iodine/ triiodide solutions are unstable. Under alkaline conditions, iodine will disproportionate producing iodide and iodate destroying the blue complex why is why titrations to a starch must be done below ph 8 but not in acidic conditions

## Answer and Explanation: 1

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View this answerA. Reactions involved:

{eq}IO_3^-+5I^-+6H^+\rightarrow \:3I_2+3H_2O{/eq}

{eq}I_2+S_2O_3^{2-}\rightarrow 2I^-+S_4O_6^{2-}{/eq}

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Chapter 3 / Lesson 18Identify the concentration of a common household chemical, hydrogen peroxide. Using a known concentration of potassium permanganate, you'll be able to perform a titration experiment to discover the unknown concentration of hydrogen peroxide.

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