Quiz 8 Bleach-solutions

Quiz 8 Bleach-solutions - Version 098/ABCAC Quiz 8 Bleach...

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Unformatted text preview: Version 098/ABCAC Quiz 8 Bleach lyon (51155) 1 This print-out should have 10 questions. Multiple-choice questions may continue on the next column or page find all choices before answering. 1 2 3 4 5 6 7 AA AB AC AD BA BB BC 8 9 10 BACK NEXT BD CA CB CC CD 001 10.0 points Liquid bleaches and powered bleaches have the same active ingredient as the bleach used in experiment 8. What is the active ingredient in most liquid bleaches and bleaching powders? 1. hypochlorite ion (ClO- ) correct 2. hydrogen peroxide (H 2 O 2 ) 3. chlorine (Cl 2 ) 4. sodium hydroxide (NaOH) 5. sodium dichromate (Na 2 Cr 2 O 7 ) Explanation: 002 10.0 points An excess of KI was added to a 0 . 475 g sam- ple of bleach. The liberated iodine required 3 . 7 mL of 0 . 0504 M Na 2 S 2 O 3 solution for the titration to reach the end point. What is the oxidizing capacity of the NaClO in the bleach? The molar mass of NaClO is 74.5 g/mol. 1. . 584958 % 2. 1 . 16992 % 3. . 877437 % 4. . 292479 % 5. 1 . 4624 % correct Explanation: Two moles of Na 2 S 2 O 3 are required for ev- ery mole of hypochlorite in the reaction. (0 . 0037 LNa 2 S 2 O 3 ) parenleftbigg . 0504Na 2 S 2 O 3 1 LNa 2 S 2 O 3 parenrightbiggparenleftbigg 1molNaC 2 mol Na 2 Convert the moles of NaClO to grams of NaClO: ( 9 . 324 10- 5 molesNaClO ) parenleftbigg 74 . 5 gNaClO 1 mol NaClO parenrightbigg = 0 . the percentage by mass of NaClO: %NaClO = . 00694638 g . 475 g 100 = 1 . 4624% This is the oxidizing capacity of the bleach. 003 10.0 points For the forward redox reaction Cl 2 (g) + 2 NaOH(aq) NaCl(aq) + NaOCl(aq) + H 2 O( ) to prepare bleach, identify the substance re- duced by the change in oxidation numbers.duced by the change in oxidation numbers....
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This note was uploaded on 12/13/2011 for the course CH 204 taught by Professor Leytner during the Fall '08 term at University of Texas at Austin.

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Quiz 8 Bleach-solutions - Version 098/ABCAC Quiz 8 Bleach...

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