Chapter 8 Second Half OWL

Chapter 8 Second Half OWL - Wh ich of the following aqueous...

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Unformatted text preview: Wh ich of the following aqueous solutions are good buffer systems ? . 0.28 M ammonium nitrate + 0.36 M ammonia . 0.38 M acetic acid + 0.27 M sodium acetate . 0.14 M sodium hypochlorite + 0.21 M hypochlorous acid . 0.23 M hydroiodic acid + 0.24 M potassium iodide . 0.21 M nitrous acid + 0.12 M sodium nitrite . Feedback: A good buffer consists of a weak acid + its conjugate base, or, a weak base + its conjugate acid. The acid/base conjugates should have similar concentrations (within a factor of 10), so that the buffering capacity is about the same for neutralizing any strong acid or strong base added to the system. All of the concentrations are within a factor of 10 for the systems above, so consider just the compounds: System ... Buffer ? nitrous acid ... + ... sodium nitrite HNO 2 = weak acid NO 2- = conjugate base YES hydroiodic acid + potassium iodide HI = strong acid I- = conjugate base ammonium nitrate + ammonia NH 4 + = conjugate acid NH 3 = weak base YES sodium hypochlorite + hypochlorous acid ClO- = conjugate base HClO = weak acid YES acetic acid + sodium acetate CH 3 COOH = weak acid CH 3 COO- = conjugate base YES Which of the following aqueous solutions are good buffer systems ? . 0.38 M calcium chloride + 0.24 M sodium chloride . 0.15 M sodium hydroxide + 0.26 M sodium bromide . 0.24 M perchloric acid + 0.20 M sodium perchlorate . 0.14 M nitrous acid + 0.16 M sodium nitrite . 0.34 M ammonia + 0.33 M barium hydroxide . Feedback: A good buffer consists of a weak acid + its conjugate base, or, a weak base + its conjugate acid. The acid/base conjugates should have similar concentrations (within a factor of 10), so that the buffering capacity is about the same for neutralizing any strong acid or strong base added to the system. All of the concentrations are within a factor of 10 for the systems above, so consider just the compounds: System ... Buffer ? nitrous acid ... + ... sodium nitrite HNO 2 = weak acid NO 2- = conjugate base YES perchloric acid + sodium perchlorate HClO 4 = strong acid ClO 4- = conjugate base ammonia + barium hydroxide NH 3 = weak base Ba(OH) 2 = strong base sodium hydroxide + sodium bromide NaOH = strong base NaBr = neutral salt calcium chloride + sodium chloride CaCl 2 = neutral salt NaCl = neutral salt Which of the following aqueous solutions are good buffer systems ?...
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This note was uploaded on 02/22/2009 for the course CHEM 102a taught by Professor Hanusa during the Fall '06 term at Vanderbilt.

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Chapter 8 Second Half OWL - Wh ich of the following aqueous...

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