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Chemistry 14CL Acid-Base Chemistry Review

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Chemistry 14CL Acid-Base Chemistry Review Powered By Docstoc
					Chemistry 14CL Acid-Base Chemistry Review October 5, 2007 1. How many milliliters of 0.0400 M Ba(OH)2 are required to reach the equivalence point with 15.0 mL of 0.100 M HCl? 2. What volume of 0.250 M H2SO4 is required to reach the equivalence point with 38.40 mL of 0.200 M NaOH? 3. What weight of NaOH is required to neutralize 250 mL of 0.050 M HCl? 4. Calculate the pH of a 1.85 x 10-2 M solution of Ba(OH)2. 5. Calculate [H+], pH, [OH-], and pOH in 0.030 M HCl. 6. Calculate [H+] and pH for each of the following solutions. (a) 0.05 M HCl (b) 1.2 x 10-4 M HCl 7. Calculate [H+] and pH for each of the following solutions. (a) 0.05 M NaOH. (b) freshly boiled water 8. Calculate [H+] and pH for each of the following solutions. (a) 0.05 M formic acid (HCOOH) (Ka = 1.8 x 10-4) (Ka = 6.6 x 10-5) (c) 1.2 x 10-4 M benzoic acid

9. Calculate the pH half way through the titration of a 10-mL aliquot of 0.200 M HNO3 with 0.100 M NaOH. 10. Calculate the pH after 4.00 mL of base have been added in a titration of a 10-mL aliquot of 0.200 M HNO3 with 0.100 M NaOH. 11. Calculate the pH half way through the titration of a 10-mL aliquot of 0.200 M chloroacetic acid (Ka = 1.5 x 10-3) with 0.100 M NaOH. 12. Calculate the pH after 4.00 mL of base have been added in a titration of a 10-mL aliquot of 0.200 M chloroacetic acid (Ka = 1.5 x 10-3) with 0.100 M NaOH. 13. Sketch the titration curves for each of the following systems. Calculate and indicate on each sketch, the equivalence point volume, the initial pH of the solution, and at least one other pH on the titration curve. Also be sure to indicate the approximate pH of the equivalence point if this is not the second point that you choose. (a) 10.00 mL of 0.0.0500 M HNO3 (beaker) titrated with 0.100 M NaOH (buret) (b) 10.00 mL of 0.0500 M benzoic acid (Ka = 6.46 x 10-5) (beaker) titrated with 0.100 M NaOH (buret). (c) 10.00 mL of 0.0500 M TRIS (Kb =1.20 x 10-6 ) (beaker) titrated with 0.100 M HCl

14. Acid base indicators are usually weak acids, which can exist in solution as either the undissociated acid or the conjugate base. The two species have different colors. As the pH of the titration changes, the predominant form of the indicator changes from one form to the other. SA = strong acid, SB = strong base; WA = weak acid, WB= weak base pH range color of color of Appropriate indicator for Indicator of color undissociated conjugate titration of 0.1000 M reagents of change indicator base acid and base (Explain below) SA-SB WA-SB WB-SA Bromocresol 3.8 – 5.4 yellow blue green Phenolphthalein Methyl red Methyl orange 8.2 – 10.0 4.8 – 6.0 3.2 – 4.4 colorless red red pink yellow yellow

Give your reasoning for choice of titration. 15. Derive the Henderson-Hasselbalch equation 1. pH = pKa + log
[base]initial [acid]initial

from the generic mass action equilibrium expression 2. Ka = 
[H + ][A - ] [HA]

16. Under what conditions can the Henderson-Haselbalch equation be used? When is it not appropriate to use the Henderson-Haselbalch equation? 

Chemistry 14CL, F07

2

Optional Workshop


				
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Lingjuan Ma Lingjuan Ma
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