Using the pKa values in Appendix G and activity coefficients from Table 8-1, calculate the pH of each of the following buffer solutions without activity and with activity. 0.025 M NaHCO_3 and 0.0030 M NaHCO_3 0.050 M NaHCO_3 and 0.015 M Na_2CO_3 0.0050 M disodium hydrogen citrate and 0.050 M sodium dihydrogen citrate. 0.050 M citric acid and 0.0050 M sodium dihydrogen citrate 0.050 M NaF and 0.040 M HF For each buffer system from problem #4, calculation the pH of the resultant solution when 15.00 mL of 0.005000 M HCl are added, 15.00 mL of 0.0400) M NaOH is added, and 5.00 mL of 0.02500 M HCl and 8.00 mL of 0.03500 mL of NaOH are added. Assume a 100 mL sample of your buffer, made fresh for each part. Plot a titration curve of a 30.00 mL aliquot of 0.05000 M sodium hypochlorite with 0.07250 M HCl. Your plot should include a minimum of 10 points prior to the equivalence point and 10 points after the equivalence point. Plot a titration curve of a 25.00 mL aliquot of 0.1000 M diprotic weak acid (pK_1 = 2.00, pK_2 = 6.50) with 0.05000 M NaOH. Your plot should include a minimum of 10 points in each variable range of the titration curve and both equivalence points. Do NOT calculate the 1^st (acid only in solution) point (0.00 mL NaOH added). This plot has the same issue as the one in class. When titrating a weak, unknown base with HCl, you performed the following series of standardizations. Initially, you made a solution of approximately 0.1000 M NaOH and standardized this solution with KHP. You then diluted slock HCl to make a solution of approximately 0.1000 M. In an acid/base titration, you took a 25.00 mL aliquot of your HCl solution and titrated it with the standardized NaOH. Due to a bad day in lab, this standardization took more than 4 trials. Throw out any outliers. Finally, a pH titration was performed with a 25.00 mL aliquot of your unknown weak base. This solution was made by dissolving 3.4581 grams of your unknown in 250.0 mL of water. Determine the pKb of your weak base (Don't worry about error in this value!). In addition, determine the molecular mass of the base and the error in this value. This error will be slightly flawed, you only did ONE titration of your unknown, so all of your error will come from the standardizations. Data will be provided in an Excel file emailed from the Instructor after this exam has been assigned.
