Before the first titration is performed, you must mix the ascorbic acid powder sample with 1.5M [tex]H_2SO_4[/tex] and KBr. What role do these reagents play in this initial mixing?

H2SO4 acts as the strong acid and solvent to dissolve ascorbic acid, while KBr aids in the subsequent iodine titration of the ascorbic acid during the titration process.

Explanation:

In the process of titration analysis, which this problem revolves around, it's essential to understand the role of H2SO4 and KBr when mixed with ascorbic acid. The 1.5M H2SO4 (sulfuric acid) acts as a strong acid and acts as a solvent that helps dissolve the ascorbic acid. The sulfuric acid also provides the acidic environment required for the redox reaction that will later occur during the titration process. KBr, on the other hand, is involved in the subsequent iodine titration of ascorbic acid. The KBr (potassium bromide) will react with the sulfuric acid to produce bromine, which can then oxidize iodide ions to iodine. The iodine generated is directly proportional to the ascorbic acid concentration and can be titrated using a known thiosulfate solution. This, in turn, allows the calculation of the ascorbic acid concentration in the powder sample.

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