Prepare a 250-mL buffer with pH = 4.40 from solid reagents benzoic acid (; M = 122.123 ) and sodium benzoate (; M = 144.105 ). The for potassium dihydrogen phosphate is 4.202. a. Write the balanced equation showing the equilibrium of the buffer solution. b. Calculate the concentration ratio of benzoate to benzoic acid using the Henderson- Hasselbalch Equation. c. Determine the amounts (in mol) of and required to prepare the buffer. d. Determine the mass of and required to prepare the buffer. e. How is the buffer solution prepared? Write a step-by-step procedure

Prepare a 250-mL buffer with pH = 4.40 from solid reagents benzoic acid (; M = 122.123 ) and sodium benzoate (; M = 144.105 ). The for potassium dihydrogen phosphate is 4.202. a. Write the balanced equation showing the equilibrium of the buffer solution. b. Calculate the concentration ratio of benzoate to benzoic acid using the Henderson- Hasselbalch Equation. c. Determine the amounts (in mol) of and required to prepare the buffer. d. Determine the mass of and required to prepare the buffer. e. How is the buffer solution prepared? Write a step-by-step procedure

Appl Of Ms Excel In Analytical Chemistry

2nd Edition

ISBN:9781285686691

Author:Crouch

Publisher:Crouch

Chapter8: Polyfunctional Acids And Bases

Section: Chapter Questions

Problem 9P

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Can someone please explain why and how the step 1 was done? What was its purpose? Why was only the pKa2 value was used in the second step 2? I don't understand shortcuts and I would appreciate it if it's explained step by step. This was the solution to my previous question in which I asked: What is the pH of a buffer prepared by mixing 100 mL 0.050 mM NaH2PO4 and 25 mL 0.075 mM Na2HPO4? (pKa1=2.2; pKa2= 7.21; pKa3=12.7)
A buffer of acetic acid and sodium acetate is prepared by mixing 10.0 mL of 0.50 M acetic acid with 0.41 grams of sodium acetate (molar mass = 82.0343 grams/mole). Calculate the concentration of acetic acid and acetate ion in the buffer (total volume of the solution is 100.0 mL). Additionally, the pH of the solution is 4.75. Explain why this is significant.
Use the Henderson-Hasselbach equation to perform the following calculations. The K, of acetic acid is1.8 × 10-5. These calculations will be graded by your instructor before preparation of the buffers.1. Buffer A: Calculate the mass of solid sodium acetate trihydrate required to mix with 100.0 mL of0.10 M acetic acid to prepare a pH 4.00 buffer.2. Buffer B: Calculate the mass of solid sodium acetate trihydrate required to mix with 100.0 mL of1.0 M acetic acid to prepare a pH 4.00 buffer.
Preparation of 40 mL of an acetate buffer (pH 4.2) 0.2 M acetic acid (pKa = 4.8) and 0.2 M sodium acetate solutions are provided. Q show the calculation the volumes of the two solutions (acetic acid and sodium acetate) should be mixed for the preparation of the acetic buffer with pH 4.2 by the Henderson-Hasselbalch equation.
A solution was prepared by mixing 50 mL of 0.1 M benzoic acid with 50 mL of 0.05 M sodium benzoate. The Ka of benzoic acid is 6.3 x 10-5. Compute for the pH value of the resulting buffer.
A buffer was made by mixing 0.1404 moles of HN3 with 0.1025 moles of KN3 and diluting to exactly 1 liter. What will be the pH after addition of 10.00 mL of 0.2367 M HBr to 50.00 mL of the buffer? Ka(HN3) = 1.900e-5. Note: only a portion of the original buffer is used in the second part of the problem.
a). What are acids, bases and buffers?b) What are the different types of buffers? Describe the mechanism howbuffers resist pH change in a system.c) Elaborate all chemical reactions in the standardization of NaOH withKHP?d) Why do you need to use KHP in the standardization of NaOH?e) Why is phenolphthalein used as an indicator in this experiment?f) Compare and contrast: endpoint vs equivalence point.g) Discuss the role of acids, bases, buffers and pH in water qualitymonitoring and post-harvest fisheries.
A 24.0 mL sample of 0.113 MM sulfurous acid (H2SO3) is titrated with 0.1013 M KOH. At what added volume of base solution does the first equivalence point occur?
1. Refer to Appendix 6 which shows the calculations involved in determining the volumes of 0.20 M acetic acid and 0.20 M sodium acetate needed to make 20.00 mL of a buffer with pH = 5.00. Study the method used: set up two equations with two unknowns; the first is the Henderson-Hasselbalch equation, the second is the fact that the volumes of HA and A− solutions should sum to 20 mL. In the Henderson-Hasselbalch equation, use the same volumes for the ratio, since the concentrations of the HA and A− solutions are the same, and the change in the ratio is due to the different volumes. Once you understand the method, use it to calculate the volumes of 0.20 M acetic acid and 0.20 M sodium acetate needed to make 20.00 mL of a buffer having pH = 4.00 and again to make 20.00 mL of a buffer with pH = 6.00. Your TA will check the accuracy of your calculations before you mix your buffer solutions. 2. Between the three buffers (pH 4, pH 5, pH 6), which will stay in the buffer region for the…
A 20.0 mL sample of 0.115 M sulfurous acid (H2SO3) solution is titrated with 0.1014 M KOH. At what added volume of base solution does each equivalence point occur?
Calculations for Acetate Buffer Solutions 2. Molarity of sodium acetate in acetate buffer. 2. Calucate the moles of acetic acid in 250.0 mL acetate buffer (below is the data to answer the answer) Deionized water Acetate Buffer Ammonia Buffer pH of solution 6.62 4.59 9.49 Ph of solution after addition of 1 mL of 0.6 M NaOH 12.41 4.71 9.50 pH of solution after addition of 1 mL of 0.6 M HCl 1.38 3.87 9.24 Preparation of Buffer solutions Mass of sodium acetate in acetate buffer ~ 1.1981 Volume of 3.0 M acetic acid in acetate buffrer ~ 3.81 Mass of ammonium chloride ~ 1.2721 Volume of 5.0 M NH4OH ~ 6.00 (both questions go together... thanks!)
Consider a buffer solution that contains 0.55 M NH2CH2CO2H and 0.35 M NH2CH2CO2Na. pKa(NH2CH2CO2H)=9.88. a. Calculate the change in pH if 0.155 g of solid NaOH is added to 250 mL of this solution. b. If the acceptable buffer range of the solution is ±0.10 pH units, calculate how many moles of H3O+ can be neutralized by 250 mL of the initial buffer. c. Calculate its pH.