A 0.2521-g sample of an unknown weak acid is titrated with a 0.1005 M NaOH, requiring 42.68 mL to reach the phenolphthalein end point. Determine the compound's equivalent weight. Which of the following compounds is most likely to be the unknown weak acid? Name Formula MM, g/mol Туре Ascorbic acid C6H8O6 176.1 Monoprotic Malonic acid C3H4O4 104.1 Diprotic Succinic acid C,HO4 118.1 Diprotic Citric acid C6H§O7 192.1 Triprotic

A 0.2521-g sample of an unknown weak acid is titrated with a 0.1005 M NaOH, requiring 42.68 mL to reach the phenolphthalein end point. Determine the compound's equivalent weight. Which of the following compounds is most likely to be the unknown weak acid? Name Formula MM, g/mol Туре Ascorbic acid C6H8O6 176.1 Monoprotic Malonic acid C3H4O4 104.1 Diprotic Succinic acid C,HO4 118.1 Diprotic Citric acid C6H§O7 192.1 Triprotic

Chemistry: Principles and Reactions

8th Edition

ISBN:9781305079373

Author:William L. Masterton, Cecile N. Hurley

Publisher:William L. Masterton, Cecile N. Hurley

Chapter14: Equilibria In Acid-base Solutions

Section: Chapter Questions

Problem 74QAP: Fifty cm3 of 1.000 M nitrous acid is titrated with 0.850 M NaOH. What is the pH of the solution (a)...

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When 40.00 mL of a weak monoprotic acid solution is titrated with 0.100-M NaOH, the equivalence point is reached when 35.00 mL base has been added. After 20.00 mL NaOH solution has been added, the titration mixture has a pH of 5.75. Calculate the ionization constant of the acid.
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.)
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.
Fifty cm3 of 1.000 M nitrous acid is titrated with 0.850 M NaOH. What is the pH of the solution (a) before any NaOH is added? (b) at half-neutralization? (c) at the equivalence point? (d) when 0.10 mL less than the volume of NaOH to reach the equivalence point is added? (e) when 0.10 mL more than the volume of NaOH to reach the equivalence point is added? (f) Use your data to construct a plot similar to that shown in Figure 14.10 (pH versus volume NaOH added).
Potassium hydrogen phthalate, known as KHP (molar mass = 204.22 g/mol), can be obtained in high purity and is used to determine the concentration of solutions of strong bases by the reaction HP(aq)+OH(aq)H2O(l)+P2(aq) If a typical titration experiment begins with approximately 0.5 g KHP and has a final volume of about 100 mL, what is an appropriate indicator to use? The pKa for HP is 5.51.
For the titration of 50.0 mL of 0.150 M ethylamine. C2H5NH2, with 0.100 M HCl, find the pH at each of the following points, and then use that information to sketch the titration curve and decide on an appropriate indicator. (a) At the beginning, before HCl is added (b) At the halfway point in the titration (c) When 75% of the required acid has been added (d) At the equivalence point (e) When 10.0 mL more HCl has been added than is required (f) Sketch the titration curve. (g) Suggest an appropriate indicator for this titration.
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.
A 0.2481 M solution of KOH is used to titrate 30.00 mL of 0.269 M hydrobromic acid. Assume that volumes are additive. (a) Write a balanced net ionic equation for the reaction that takes place during the titration. (b) What are the species present at the equivalence point? (c) What volume of KOH is required to reach the equivalence point? (d) What is the pH of the solution 1. before any KOH is added? 2. halfway to the equivalence point? 3. at the equivalence point?
Aniline hydrochloride, (C6H5NH3)Cl, is a weak acid. (Its conjugate base is the weak base aniline, C6H5NH2.) The acid can be titrated with a strong base such as NaOH. C6H5NH3+(aq)+OH(aq)C6H5NH2(aq)+H2O(l) Assume 50.0 mL of 0.100 M aniline hydrochloride is titrated with 0.185 M NaOH. (Ka for aniline hydrochloride is 2.4 105.) (a) What is the pH of the (C6H5NH3) solution before the titration begins? (b) What is the pH at the equivalence point? (c) What is the pH at the halfway point of the titration? (d) Which indicator in Figure 17.11 could be used to detect the equivalence point? (e) Calculate the pH of the solution after adding 10.0, 20.0, and 30.0 mL of base. (f) Combine the information in parts (a), (b), (c), and (e), and plot an approximate titration curve.
Consider the nanoscale-level representations for Question 110 of the titration of the aqueous weak acid HX with aqueous NaOH, the titrant. Water molecules and Na+ ions are omitted for clarity. Which diagram corresponds to the situation: After a very small volume of titrant has been added to the initial HX solution? When enough titrant has been added to take the solution just past the equivalence point? Halfway to the equivalence point? At the equivalence point? Nanoscale representations for Question 110.