# Pts calculate the number of moles of acetic acid that

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3. (3 pts) Calculate the number of moles of acetic acid that were present in the original buffer solution prepared in Step 18 of the procedure. Assume no change in volume upon addition of sodium acetate trihydrate. Discuss this calculation.
4. (3 pts) Calculate the number of moles of acetate that were present in the original buffer solution prepared in Step 18 of the procedure. The molecular mass of sodium acetate trihydrate is 136.08 g/mol. Discuss this calculation.
5 A. M. Bohnsack Spring 2019 (revised Z. Baranová)
Worksheet & Grading Rubric – Weak Acids and Buffers In order to find the number of moles of acetate in the buffer solution, you have to divide the mass gathered by the molar mass. In this case, we gathered 0.0075 moles of acetate. 5. (3 pts) Use the Henderson–Hasselbalch equation to calculate the theoretical pH of the buffer solution (prior to the addition of NaOH) using the values obtained in Discussion Questions 3 and 4 and the theoretical value of Ka for acetic acid, 1.8 10 –5 . Discuss this calculation.
6. (2 pts) What was the measured pH of the buffer solution prior to the addition of NaOH? Use the theoretical pH calculated in Discussion Question 5 and the following equation to determine and discuss the % error of your results: % error = | theoretical pH measured pH theoretical pH | × 100 | 4.74 4.84 4.74 | × 100% = ¿ 2% a. The theoretical pH of 4.74 didn’t differ largely from the measured pH of 4.84 leading us to have a fairly low error percentage of 2%. 7. (3 pts) During the addition of NaOH in Part B , which buffer species reacted with the NaOH? Provide the balanced formula unit equation for this reaction. O