EXPERIMENT 22 POST-LABORATORY QUESTIONS Some cleansers contain bromate salts as

Question

EXPERIMENT 22 POST-LABORATORY QUESTIONS Some cleansers contain bromate salts as the oxidizing agent. The bromate ion, BrO3" oxidizes the iodide ion as follows: 1. BrO3, +61_ + 6 H+ 312 + Br + 3H2O On a molar basis, which is a more effective bleaching agent, KBrO3 or NaOCI? 2. Explain why analysis of commercial bleaching solutions will often show a lower OCI ion content than is advertised on the bottle. (Hint: This is especially true if the bleach container seal is not on tight.) 3. A student prepared all of his titration mixtures, containing diluted bleach, KI solution, and HCl solution, at the some time. Why was the precision poor? 4. How many electrons are exchanged in the reaction in problem (1)?

Explanation / Answer

Q1

if "molar" implies how much mass is required per unit mol

then, choose NaOCl, since it is much more lighter

Alo, note that NaOCl will oxidize the same amount than BrO3- ions

Q2

Note that CO2 from atmosphere will be present in solution

CO2 + H2O = H2CO3

there is acid present

acid neutralizes the OCl-

H2CO3 + OCl- = HOCl + HCO3-

therefore, OCl- content decreases

Q3

"at some time" implies that there is not added intially, therefore, the total addition of subnstance reuqired is not total

Q$

I goes from -1 to 0, therefore

6x1 = 6 e- are transferred

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