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StoichiometryMCQ

The active ingredient in commercial bleach is sodium hypochlorite, NaOCl, which can be determined byStoichiometry Chemistry Question

Question

The active ingredient in commercial bleach is sodium hypochlorite, NaOCl, which can be determined by iodometric analysis as indicated in these equations.
OCl– + 2H+ + 2I– → I2 + Cl– + H2O
I2 + 2S2O3 2– → S4O6 2– + 2I–
If 1.356 g of a bleach sample requires 19.50 mL of 0.100 M Na2S2O3 solution, what is the percentage by mass of NaOCl in the bleach?

A.

2.68%

B.

3.70%

C.

5.35%

✓ Correct
D.

10.7%

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