1. It has been calculated that a 0.150 M solution of formic acid at 25°C (pKa = 3.75) has a pH of 2.28. Is there a change to the pH of the solution if enough solid sodium formate is added to make the final formate concentration 0.100 M in 100 mL total (assume that the formic acid concentration does not change)? 2. 100 mL buffer solution contains 0.135 M HCO2H and 0.215 M HCO2Na and had a pH of 3.95. a) What is the final pH if 5.00 mL of 1.00 M HCl are added to 100 mL of this solution? b) What is the final pH if 5.00 mL of 1.00 M NaOH are added? 3.100 mL of a buffer solution contains 0.119 M pyridine and 0.234 M pyridine hydrochloride and had a pH of 4.94. What is the final pH if 12.0 mL of 1.5 M NaOH are added to 250 mL of this solution? What is the final pH if 12.0 mL of 1.5 M HCl are added? 4. What is the pH of a solution which is 0.0400 M in formic acid, HCO2H, and 0.0600 M in sodium formate, NaHCOO? (a) 3.92 (b) 3.96 (c) 4.00 (d) 9.52 (e) 4.08 5.What is the pH of a solution containing aqueous ammonia and ammonium nitrate in a molar ratio of 5.0 to 3.0? (a) 4.52 (b) 4.96 (c) 9.04 (d) 9.26 (e) 9.48 6. Determine the pH at each of the following points in the titration of 15 mL of 0.1 M HI with 0.5 M LiOH
7. Determine the pH at each of the following points in the titration of 10 mL of 0.05 M Ba(OH)2 with 0.1 M HNO3
8. When does the equivalence point of 15 mL of 0.15 M CH3COOH titrated with 0.1 M NaOH occur? 9. Sketch a titration curve for the titration of 25.0 mL of 0.125 M NH3 with 0.0625 M HCl given the following data points: VHCl = 5 mL, pH = 10.24 VHCl = 45 mL, pH = 8.24 VHCl = 60 mL, pH = 2.13 VHCl = 80 mL, pH = 1.75 10. Blood is buffered by carbonic acid and the bicarbonate ion. Normal blood plasma is 0.024 M in HCO3- and 0.0012 M H2CO3 (pka for H2CO3at body temperature is 6.1).
The pKa of benzoic acid is 4.20, and the pKb of trimethylamine is also 4.20. 14.The buffer solution from Example 15 contained 0.119 M pyridine and 0.234 M pyridine hydrochloride and had a pH of 4.94.
15.Salicylic acid is used in the synthesis of acetylsalicylic acid, or aspirin. One gram dissolves in 460 mL of water to create a saturated solution with a pH of 2.40.
16. Calculate the pH of a solution prepared by adding 40.00 mL of 0.237 M HCl to 75.00 mL of a 0.133 M solution of NaOH. 17. Calculate the pH of a solution prepared by adding 45.0 mL of a 0.213 M HCl solution to 125.0 mL of a 0.150 M solution of ammonia. The pKb of ammonia is 4.75 at 25°C. 18. What volume of 0.50 M HCl is needed to completely neutralize 25.00 mL of 0.86 M NaOH? 19. Fill in the data for the titration of 50.0 mL of 0.241 M formic acid with 0.0982 M KOH. The pKa of formic acid is 3.75. What is the pH of the solution at the equivalence point?
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Subpages (1): Answers to Ch 18 EofCh Problems