Textbook Question
Consider the titration of 50.0 mL of 1.00 M H3PO4 with 1.00 M KOH. Calculate the pH after the addition of each of the following volumes of base. (a) 25.0 mL (c) 75.0 mL
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Ch.17 - Applications of Aqueous Equilibria
Chapter 17, Problem 2
What is the percent dissociation in a solution that is 0.50 M in acetic acid (CH3CO2H) and 0.10 M in sodium acetate (NaCH3CO2)? (Ka = 1.8 x 10^-5) (a) 0.018% (b) 0.090% (c) 7.2 x 10^-3% (d) 2.3%
Verified step by step guidance1
Identify the components of the solution: acetic acid (CH3CO2H) is a weak acid, and sodium acetate (NaCH3CO2) is its conjugate base. This is a buffer solution.
Use the Henderson-Hasselbalch equation to find the pH of the buffer solution: \( \text{pH} = \text{pKa} + \log \left( \frac{[\text{A}^-]}{[\text{HA}]} \right) \), where \([\text{A}^-]\) is the concentration of the acetate ion and \([\text{HA}]\) is the concentration of acetic acid.
Calculate the pKa from the given Ka: \( \text{pKa} = -\log(1.8 \times 10^{-5}) \).
Substitute the concentrations of acetic acid and acetate ion into the Henderson-Hasselbalch equation to find the pH.
Use the pH to determine the percent dissociation of acetic acid: \( \% \text{dissociation} = \left( \frac{[\text{H}^+]}{[\text{HA}]} \right) \times 100 \), where \([\text{H}^+]\) is the concentration of hydrogen ions calculated from the pH.
Related Practice
Textbook Question
Consider the titration of 50.0 mL of a 0.100 M solution of the protonated form of the amino acid alanine (H2A+: Ka1 = 4.6 × 10–3, Ka2 = 2.0 × 10–10) with 0.100 M NaOH. Calculate the pH after the addition of each of the following volumes of base. (b) 25.0 mL (c) 50.0 mL
Textbook Question
Which of the following mixtures has the highest pH?
(a) Equal volumes of 1.0 M HCl and 1.0 M NaOH
(b) Equal volumes of 0.1 M HNO3 and 0.1 M KOH
(c) Equal volumes of 0.1 M HCN and 0.1 M NaOH
(d) Equal volumes of 0.1 M NaF and 0.1 M HCl
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Textbook Question
A 1.00 L buffer solution is 0.250 M in HF and 0.250 M in NaF. Calculate the pH of the solution after the addition of 100.0 mL of 1.00 M HCl. (Ka = 3.5 x 10^-4)
(a) 4.11
(b) 3.82
(c) 3.46
(d) 3.09
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Textbook Question
What is the pH of a buffer solution prepared by dissolving 0.250 mol of NaH2PO4 and 0.075 mol of NaOH in enough water to make 1.00 L of solution? (Ka (H2PO4-) = 6.2 X 10^-8)
(a) 6.32
(b) 6.83
(c) 7.21
(d) 7.71
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Open Question
Which is the best acid-base pair to use in the preparation of a buffer with pH = 10.5? (a) HOI and OI- (Ka = 2.0 x 10^-11) (b) HNO2 and NO2- (Ka = 4.5 x 10^-4) (c) HIO3 and IO3- (Ka = 1.7 x 10^-1) (d) H2PO4^- and HPO4^2- (Ka = 6.2 x 10^-8)