CHEM #5 Quiz

CHEM #5 Quiz - 1. (Points: 4) The Ka of hypochlorous acid,...

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1.  (Points: 4)      The K a of hypochlorous acid, HClO, is 3.5 × 10 -8 . What [ClO - ]/[HClO] ratio is necessary to make a buffer with a pH of 7.71? Paragraph  Insert equation    Save Answer     2.  (Points: 4)      A buffer contains 1.0 mol CH 3 CO 2 H and 1.0 mol CH 3 CO 2 - diluted with water to 1.0 L. How many moles of NaOH are required to increase the pH of the buffer to 5.10? (p K a of CH 3 CO 2 H = 4.74) Paragraph  Insert equation    Save Answer     3.  (Points: 4)      A volume of 25.0 mL of 0.100 M HCO 2 H(aq) is titrated with 0.100 M NaOH(aq). What is the pH after the addition of 12.5 mL of NaOH? ( K a for HCO 2 H = 1.8 × 10 -4 ) Paragraph  Insert equation    Save Answer  
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1.  (Points: 4)      4.  (Points: 4)      What is the effect of adding 10 mL of 0.1 M NaOH(aq) to 100 mL of 0.2 M NH 4 + (aq)? 1. 2. 3. a.  1 only b.  2 only c.  3 only d.  2 and 3 e.  1, 2, and 3   Save Answer     5.  (Points: 4)      Which of the following combinations would be the best to buffer an aqueous solution at a pH of 5.0? a.  H 3 PO 4 and H 2 PO 4 - , K a = 7.5 × 10 -3 b.  HNO 2 and NO 2 - , K a = 4.5 × 10 -4
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1.  (Points: 4)    c.  CH 3 CO 2 H and CH 3 COO - , K a = 1.8 × 10 -5 d.  H 2 PO 4 - and HPO 4 2- , K a = 6.2 × 10 -8 e.  NH 4 + and NH 3 , K a = 5.7 × 10 -10   Save Answer     6.  (Points: 4)      Each of the following mixtures can produce an effective buffer solution EXCEPT a.  HClO 4 and NaClO 4 . b.  HF and NaF. c.  NaHCO 3 and Na 2 CO 3 . d.  Na 2 HPO 4 and Na 3 PO 4 . e.  NH 4 Cl and NH 3 .   Save Answer     7.  (Points: 4)      All of the following statements concerning buffers are true EXCEPT a.  buffers are resistant pH changes upon
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1.  (Points: 4)    addition of small quantities of strong acids or bases. b. 
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This note was uploaded on 11/16/2008 for the course CHM 152 taught by Professor Thomas during the Fall '08 term at Pima CC.

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CHEM #5 Quiz - 1. (Points: 4) The Ka of hypochlorous acid,...

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