Titrating with 0.1 M NAOH we red 270 Buffer 1 Buffer 2 DI water 0.1 M acetic acid (mL) 10 35 0.5 M sodium acetate 2 7 (mL) Water (mL) Initial pH Final pH Buffer Concentration Initial Burette Reading Final Burette Reading Delivered Titrant (mL) 38 4-13 5-13 8..28 49-06 48-63 3819 E4-153 5-16 30 22 43-63 135ク 50 9•20 10-01 436 35-53 25-73 Ka of acetic acid= %3D Calculated theoretical pH of Buffer 1: Calculated theoretical pH of Buffer 2:

Titrating with 0.1 M NAOH we red 270 Buffer 1 Buffer 2 DI water 0.1 M acetic acid (mL) 10 35 0.5 M sodium acetate 2 7 (mL) Water (mL) Initial pH Final pH Buffer Concentration Initial Burette Reading Final Burette Reading Delivered Titrant (mL) 38 4-13 5-13 8..28 49-06 48-63 3819 E4-153 5-16 30 22 43-63 135ク 50 9•20 10-01 436 35-53 25-73 Ka of acetic acid= %3D Calculated theoretical pH of Buffer 1: Calculated theoretical pH of Buffer 2:

Chemistry: The Molecular Science

5th Edition

ISBN:9781285199047

Author:John W. Moore, Conrad L. Stanitski

Publisher:John W. Moore, Conrad L. Stanitski

Chapter15: Additional Aqueous Equilibria

Section: Chapter Questions

Problem 31QRT

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Similar questions

A buffer is prepared by dissolving 0.062 mol of sodium fluoride in 127 mL of 0.0399 M hydrofluoric acid. Assume no volume change after NaF is added. Calculate the pH of this buffer.
Methyl red has the following structure: It undergoes a color change from red to yellow as a solution gets more basic. Calculate an approximate pH range for which methyl red is useful. What is the color change and the pH at the color change when a weak acid is titrated with a strong base using methyl red as an indicator? What is the color change and the pH at the color change when a weak base is titrated with a strong acid using methyl red as an indicator? For which of these two types of titrations is methyl red a possible indicator?
Malonic acid (HO2CCH2CO2H) is a diprotic acid. In the titration of malonic acid w ith NaOH, stoichiometric points occur at pH = 3.9 and 8.8. A 25.00-mL sample of malonic acid of unknown concentration is titrated with 0.0984 M NaOH, requiring 31.50 mL of the NaOH solution to reach the phenolphthalein end point. Calculate the concentration of the initial malonic acid solution. (Sec Exercise 113.)
A buffer is composed of formic acid and its conjugate base, the formate ion. (a) What is the pH of a solution that has a formic acid concentration of 0.050 M and a sodium formate concentration of 0.035 M? (b) What must the ratio of acid to conjugate base be to have a pH value 0.50 units higher than the value calculated in part (a)?
A buffer is prepared using the butyric acid/butyrate (HC4H7O2/C4H7O2)acid-base pair. The ratio of acid to base is 2.2 and Ka for butyric acid is1.54105. (a) What is the pH of this buffer? (b) Enough strong base is added to convert 15% of butyric acid to the butyrate ion. What is the pH of the resulting solution? (c) Strong acid is added to the buffer to increase its pH. What must the acid/base ratio be so that the pH increases by exactly one unit (e.g., from 2 to 3) from the answer in (a)?
Given three acid-base indicatorsâ€”methyl orange (end point at pH 4), bromthymol blue (end point at pH 7), and phenolphthalein (end point at pH 9)â€”which would you select for the following acid-base titrations? (a) perchloric acid with an aqueous solution of ammonia (b) nitrous acid with lithium hydroxide (c) hydrobromic acid with strontium hydroxide (d) sodium fluoride with nitric acid
Using Figure 17.11, suggest an indicator to use in each of the following titrations: (a) The weak base pyridine is titrated with HCl. (b) Formic acid is titrated with NaOH. (c) Ethylenediamine, a weak diprotic base, is titrated with HCl. Figure 17.11 Common acid-base indicators. The color changes occur over a range of pH values. Notice that o few indicators hove color changes over two different pH ranges.
Cyanic acid (HOCN) is a weak acid with AL, = 3.5 X IO-4. Consider the titration of 25.0 inL of 0.125 M HOCN with 0.125 M NaOH. Calculate the pH of the solution at each of the following points. Before any NaOH has been added. .After 12.5 mL of NaOH has been added. After 23.0 inL of NaOH has been added. .After 27.0 mL of KOH have been added. Use your calculator or a spreadsheet to plot the titration curve, and use your graph to estimate the pH at the equivalence point.
Without doing detailed calculations, sketch the curve for the titration of 30.0 mL of 0.10 M NaOH with 0.10 M HCl. Indicate the approximate pH at the beginning of the titration and at the equivalence point. What is the total solution volume at the equivalence point?
The titration curves for two acids with the same base are shown on this graph. (a) Which is the curve for the weaker acid? Explain your choice. (b) Give the approximate pH at the equivalence point for the titration of each acid. (c) Explain why the pH at the equivalence point differs for each acid. (d) Explain why the starting pH values of the two acids differ. (e) Which indicator or indicators, phenolphthalein, bromthymol blue, or methyl red, could be used for the titration of Acid 1? For the titration of Acid 2? Explain your choices.
Draw the general titration curve for a strong acid titrated by a strong base. At the various points in the titration, list the major species present before any reaction takes place and the major species present after any reaction takes place. What reaction takes place in a strong acidstrong base titration? How do you calculate the pH at the various points along the curve? What is the pH at the equivalence point for a strong acidstrong base titration? Why?
Which of these buffers involving a weak acid HA has the greater resistance to change in pH? Explain your answer. (i) [HA] =0.100 M = [A] (ii) [HA] = 0.300 M = [A]