Question

6. How many mL of 0.2 M sodium acetate should be added to 200 mL of 0.2 M acetic acid to make a buffer of pH 5.5? (refer to Table 2-2 on page 60 for pKa values). What is the molarity of the resulting buffer with respect to acetate (acetate + acetic acid)? 7. How many mL of 0.2 M HCl should be added to 50 mL of 0.2 M Tris base (Trishydroxymethyl aminomethane) to make a buffer of pH 8.0 Hint: working with concentrations and then ratios of mmoles of Tris and HCL, may help solve this one). What is the molarity of Tris in the resulting Buffer? 8. Calculate the pH of a solution made by mixing 100 mL of 0.1 M NaH:POs and 300 mL of o.1 M Na2HPO4 9. To each of 100 ml of three (A, B, and C) 0.1 M acetate buffer solutions (pH of A-4.0, pH of B- 4.76, pH of C 5.5), 10 mL of 0.1 M NaOH was added. Calculate the resulting change in the pH. 10. Calculate the buffering capacity (A mmoles OH/ApH) of each of the solutions in question 9 above. How does the buffering capacity change in relationship to the pKa of acetic acid?

Answer 1