Chemistry
9th Edition
ISBN: 9781133611097
Author: Steven S. Zumdahl
Publisher: Cengage Learning
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Textbook Question
Chapter 15, Problem 82AE
a. Calculate the pH of a buffered solution that is 0.100 M in C6H5CO2H (benzoic acid, Ka = 6.4 × 10−5) and 0.100 M in C6H5CO2Na.
b. Calculate the pH after 20.0% (by moles) of the benzoic acid is converted to benzoate anion by addition of a strong base. Use the dissociation equilibrium
C6H5CO2H(aq) ⇌ C6H5CO2-(aq) + H+(aq)
to calculate the pH.
c. Do the same as in part b, but use the following equilibrium to calculate the pH:
C6H5CO2-(aq) + H2O(l) ⇌ C6H5CO2H(aq) + OH-(aq)
d. Do your answers in parts b and c agree? Explain.
Expert Solution & Answer
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6.
a. Calculate the pH of a buffered solution that is 0.100 M in C6H5CO2H (benzoic acid, Ka = 6.4 x 10-5) and 0.100 M NaC6H5CO2.
b. Calculate the pH after 20.0% (by moles) of the benzoic acid is converted to benzoate anion by addition of a strong base. Use the dissociation equilibrium: C6H5CO2H (aq) + H2O (l) ⇌ C6H5CO2- (aq) + H3O+(aq)
c. Do the same as in part b, but use the following equilibrium to calculate the pH: C6H5CO2 -(aq) + H2O(l) ⇌C6H5CO2H (aq) + OH- (aq)
d. Do your answers in part b and c agree? Explain.
A buffer solution is prepared by combining 0.795 moles of formic acid and 0.898 moles of sodium formate. What will the solution pH be if 0.120 moles of sodium hydroxide
(NaOH) is added to the buffer solution? The K₂ of formic acid is 1.8 x 10-4. (Two decimal places)
In Part A, a 15.00 mL aliquot of a 0.155 mol L-1 3-methylbutanoic acid solution was titrated to its equivalence point with 11.7 mL of 0.198 molL-1
NaOH solution. At the equivalence point, all of the weak acid, 3-methylbutanoic acid, is converted to its weak conjugate base, 3-methylbutanoate.
What is the pH at this equivalence point?
6.957
4.770
8.855
5.145
O 9.230
Chapter 15 Solutions
Chemistry
Ch. 15 - What is meant by the presence of a common ion? How...Ch. 15 - Define a buffer solution. What makes up a buffer...Ch. 15 - One of the most challenging parts of solving...Ch. 15 - A good buffer generally contains relatively equal...Ch. 15 - Draw the general titration curve for a strong acid...Ch. 15 - Instead of the titration of a strong acid by a...Ch. 15 - Sketch the titration curve for a weak acid...Ch. 15 - Sketch the titration curve for a weak base...Ch. 15 - What is an acidbase indicator? Define the...Ch. 15 - Why does an indicator change from its acid color...
Ch. 15 - What are the major species in solution after...Ch. 15 - A friend asks the following: Consider a buffered...Ch. 15 - Mixing together solutions of acetic acid and...Ch. 15 - Could a buffered solution be made by mixing...Ch. 15 - Sketch two pH curves, one for the titration of a...Ch. 15 - Sketch a pH curve for the titration of a weak acid...Ch. 15 - You have a solution of the weak acid HA and add...Ch. 15 - You have a solution of the weak acid HA and add...Ch. 15 - The common ion effect for weak acids is to...Ch. 15 - Prob. 10QCh. 15 - A best buffer has about equal quantities of weak...Ch. 15 - Consider the following pH curves for 100.0 mL of...Ch. 15 - An acid is titrated with NaOH. The following...Ch. 15 - Consider the following four titrations. i. 100.0...Ch. 15 - Figure 14-4 shows the pH curves for the titrations...Ch. 15 - Acidbase indicators mark the end point of...Ch. 15 - How many of the following are buffered solutions?...Ch. 15 - Which of the following can be classified as buffer...Ch. 15 - A certain buffer is made by dissolving NaHCO3 and...Ch. 15 - A buffer is prepared by dissolving HONH2 and...Ch. 15 - Calculate the pH of each of the following...Ch. 15 - Calculate the pH of each of the following...Ch. 15 - Compare the percent dissociation of the acid in...Ch. 15 - Compare the percent ionization of the base in...Ch. 15 - Calculate the pH after 0.020 mole of HCl is added...Ch. 15 - Calculate the pH after 0.020 mole of HCl is added...Ch. 15 - Calculate the pH after 0.020 mole of NaOH is added...Ch. 15 - Calculate the pH after 0.020 mole of NaOH is added...Ch. 15 - Which of the solutions in Exercise 21 shows the...Ch. 15 - Prob. 30ECh. 15 - Calculate the pH of a solution that is 1.00 M HNO2...Ch. 15 - Calculate the pH of a solution that is 0.60 M HF...Ch. 15 - Calculate the pH after 0.10 mole of NaOH is added...Ch. 15 - Calculate the pH after 0.10 mole of NaOH is added...Ch. 15 - Calculate the pH of each of the following buffered...Ch. 15 - Calculate the pH of each of the following buffered...Ch. 15 - Calculate the pH of a buffered solution prepared...Ch. 15 - A buffered solution is made by adding 50.0 g NH4Cl...Ch. 15 - Calculate the pH after 0.010 mole of gaseous HCl...Ch. 15 - An aqueous solution contains dissolved C6H5NH3Cl...Ch. 15 - Calculate the mass of sodium acetate that must be...Ch. 15 - What volumes of 0.50 M HNO2 and 0.50 M NaNO2 must...Ch. 15 - Consider a solution that contains both C5H5N and...Ch. 15 - Calculate the ratio [NH3]/[NH4+] in...Ch. 15 - Carbonate buffers are important in regulating the...Ch. 15 - When a person exercises, muscle contractions...Ch. 15 - Consider the acids in Table 13-2. 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After adding 30.0...Ch. 15 - A student dissolves 0.0100 mole of an unknown weak...Ch. 15 - Two drops of indicator HIn (Ka = 1.0 109), where...Ch. 15 - Methyl red has the following structure: It...Ch. 15 - Potassium hydrogen phthalate, known as KHP (molar...Ch. 15 - A certain indicator HIn has a pKa of 3.00 and a...Ch. 15 - Which of the indicators in Fig. 14-8 could be used...Ch. 15 - Prob. 74ECh. 15 - Which of the indicators in Fig. 14-8 could be used...Ch. 15 - Prob. 76ECh. 15 - Estimate the pH of a solution in which bromcresol...Ch. 15 - Estimate the pH of a solution in which crystal...Ch. 15 - A solution has a pH of 7.0. What would be the...Ch. 15 - A solution has a pH of 4.5. What would be the...Ch. 15 - Derive an equation analogous to the...Ch. 15 - a. 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H2A. is titrated with NaOH,...Ch. 15 - Prob. 114CPCh. 15 - The titration of Na2CO3 with HCl bas the following...Ch. 15 - Consider the titration curve in Exercise 115 for...Ch. 15 - A few drops of each of the indicators shown in the...Ch. 15 - Malonic acid (HO2CCH2CO2H) is a diprotic acid. In...Ch. 15 - A buffer solution is prepared by mixing 75.0 mL of...Ch. 15 - A 10.00-g sample of the ionic compound NaA, where...Ch. 15 - Calculate the pH of a solution prepared by mixing...Ch. 15 - Consider a solution prepared by mixing the...
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