5) In order to determine the Kb of an unknown weak base, you decide to perform a titration. You accurately measure out 175.0 mg of the base, and dissolve it in a total solution volume of 25.0 mL. After that, you titrant the solution with 0.150 M HBr, and get the data shown in the table below. From this information, answer the following questions. Volume of HBr pH 0 mL a. Construct a fully labeled titration curve. 11.96 b. Determine the Kb of the weak base. 13.0 mL 10.75 c. Determine the molar mass of the weak 26.0 mL base. 30.0 mL 5.90 1.96

5) In order to determine the Kb of an unknown weak base, you decide to perform a titration. You accurately measure out 175.0 mg of the base, and dissolve it in a total solution volume of 25.0 mL. After that, you titrant the solution with 0.150 M HBr, and get the data shown in the table below. From this information, answer the following questions. Volume of HBr pH 0 mL a. Construct a fully labeled titration curve. 11.96 b. Determine the Kb of the weak base. 13.0 mL 10.75 c. Determine the molar mass of the weak 26.0 mL base. 30.0 mL 5.90 1.96

Chemistry

9th Edition

ISBN:9781133611097

Author:Steven S. Zumdahl

Publisher:Steven S. Zumdahl

Chapter15: Acid-base Equilibria

Section: Chapter Questions

Problem 7ALQ: You have a solution of the weak acid HA and add some HCl to it. What are the major species in the...

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. Which component of a buffered solution is capable of combining with an added strong acid? Using your example from Exercise 60, show how this component would react with added HC1.
You have a solution of the weak acid HA and add some HCl to it. What are the major species in the solution? What do you need to know to calculate the pH of the solution, and how would you use this information? How does the pH of the solution of just the HA compare with that of the final mixture? Explain.
Sketch the titration curve for a weak acid titrated by a strong base. When performing calculations concerning weak acidstrong base titrations, the general two-slep procedure is to solve a stoichiometry problem first, then to solve an equilibrium problem to determine the pH. What reaction takes place in the stoichiometry part of the problem? What is assumed about this reaction? At the various points in your titration curve, list the major species present after the strong base (NaOH, for example) reacts to completion with the weak acid, HA. What equilibrium problem would you solve at the various points in your titration curve to calculate the pH? Why is pH 7.0 at the equivalence point of a weak acid-strong base titration? Does the pH at the halfway point to equivalence have to be less than 7.0? What does the pH at the halfway point equal? Compare and contrast the titration curves for a strong acidstrong base titration and a weak acidstrong base titration.
A bottle of concentrated hydroiodic acid is 57% HI by weight and has a density of 1.70 g/mL. A solution of this strong and corrosive acid is made by adding exactly 10.0 mL to some water and diluting to 250.0 mL. If the information on the label is correct, what volume of 0.988 M NaOH is needed to neutralize the HI solution? Suggest an indicator for the titration.
A 2.500-g sample of a mixture of sodium carbonate and sodium chloride is dissolved in 25.00 mL of 0.798 M HCl. Some acid remains after the treatment of the sample. a Write the net ionic equation for the complete reaction of sodium carbonate with hydrochloric acid b If 28.7 mL of 0.108 M NaOH were required to titrate the excess hydrochloric acid, how many moles of sodium carbonate were present in the original sample? c What is the percent composition of the original sample?
Another way to treat data from a pH titration is to graph the absolute value of the change in pH per change in milliliters added versus milliliters added (pH/mL versus mL added). Make this graph using your results from Exercise 61. What advantage might this method have over the traditional method for treating titration data?
Benzoic acid (K a=6.6105)is present in many berries. Calculate the pH and % ionization of a 726-mL solution that contains 0.288 mol of benzoic acid.
A friend asks the following: Consider a buffered solution made up of the weak acid HA and its salt NaA. If a strong base like NaOH is added, the HA reacts with the OH to form A. Thus the amount of acid (HA) is decreased, and the amount of base (A) is increased. Analogously, adding HCI to the buffered solution forms more of the acid (HA) by reacting with the base (A). Thus how can we claim that a buffered solution resists changes in the pH of the solution? How would you explain buffering to this friend?