Open Question
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%
Ch.17 - Applications of Aqueous Equilibria
Chapter 17, Problem 5
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)
Verified step by step guidance1
Step 1: Understand that a buffer solution is most effective when the pH is close to the pKa of the acid in the acid-base pair.
Step 2: Calculate the pKa for each acid using the formula pKa = -log(Ka).
Step 3: Compare the calculated pKa values to the desired pH of 10.5.
Step 4: Identify the acid-base pair whose pKa is closest to the desired pH of 10.5.
Step 5: Select the acid-base pair with the pKa closest to 10.5 as the best choice for the buffer solution.
Related Practice
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
Calculate the concentrations of NH4+ and NH3 and the pH in a solution prepared by mixing 20.0 g of NaOH and 0.500 L of 1.5 M NH4Cl. Assume that the volume remains constant.
Open Question
A 25.00 mL sample of 1.00 M CH3CO2H is titrated with 1.00 M NaOH. Calculate the pH after 30.00 mL of NaOH has been added. (Ka = 1.8 x 10^-5) (a) 6.90 (b) 9.36 (c) 11.54 (d) 12.95
Textbook Question
The pH titration curve applies to the titration of 40.0 mL of a 0.100 M solution of an acid with 0.100 M NaOH. What are the approximate pKa values for this acid?
(a) pKa1 = 5, pKa2 = 10
(b) pKa1 = 7, pKa2 = 11
(c) pKa1 = 5, pKa2 = 10, pKa3 = 13
(d) pKa1 = 5, pKa2 = 7, pKa3 = 10
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