A 1.0-L buffer solution contains 0.300 mol acid, HA, and 0.300 mol base, NaA. The value of K, for the acid HA is 2.9x10-8. Ignoring the small volume change, what is the most likely pH of the solution if a 10.0 mL- sample of 1.00M HNO3 is added to the original buffer? 11.30 < pH < 11.45 O 7.45 < pH < 7.60 O 6.34 < pH < 6.49 く O 3.65 < pH < 3.78 く

A 1.0-L buffer solution contains 0.300 mol acid, HA, and 0.300 mol base, NaA. The value of K, for the acid HA is 2.9x10-8. Ignoring the small volume change, what is the most likely pH of the solution if a 10.0 mL- sample of 1.00M HNO3 is added to the original buffer? 11.30 < pH < 11.45 O 7.45 < pH < 7.60 O 6.34 < pH < 6.49 く O 3.65 < pH < 3.78 く

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 33QAP: A buffer is prepared in which the ratio [ H2PO4 ]/[ HPO42 ]is 3.0. (a) What is the pH of this...

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A solution consisting of 25.00 g NH4Cl in 178 mL of water is titrated with 0.114 M KOH. (a) How many milliliters of KOH are required to reach the equivalence point? (b) Calculate [Cl-], [K+], [NH3], and [OH-] at the equivalence point. (Assume that volumes are additive.) (c) What is the pH at the equivalence point?
What mass of NH4Cl must be added to 0.750 L of a 0.100-M solution of NH3 to give a buffer solution with a pH of 9.26? (Him: Assume a negligible change in volume as the solid is added.)
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?
A buffer is prepared in which the ratio [ H2PO4 ]/[ HPO42 ]is 3.0. (a) What is the pH of this buffer? (b) Enough strong acid is added to convert 15% of HPO42- to H2PO4-. What is the pH of the resulting solution? (c) Enough strong base is added to make the pH 7.00. What is the ratio of [H2PO4-] to [HPO42-] at this point?
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.
A solution is made by dissolving 15.0 g sodium hydroxide in approximately 450 mL water. The solution becomes quite warm, but after it is allowed to return to room temperature, water is added to bring the volume to 500.0 mL of solution. (a) Calculate the pH and pOH in the final solution. (b) Why would we wait for it to return to room temperature? (c) If the mass of the water used to initially dissolve the sodium hydroxide were exactly 450 g and the temperature of the water increased by 8.865 C, how much heat was given off by the dissolution of 15.0 g of solute? Assume the specific heat of the solution is 4.184 J/g. K. What is the molar heat change for the dissolution of sodium hydroxide (known as the enthalpy of solution, Hsol)?
How much solid NaCH3CO23H2O must be added to 0300 L of a 0.50-M acetic acid solution to give a buffer with a pH of 5.00? (Him: Assume a negligible change in volume as the solid is added.)
The species called glacial acetic acid is 98% acetic acid by mass (d=1.0542g/mL). What volume of glacial acetic acid must be added to 100.0 mL of 1.25 M NaOH to give a buffer with a pH of 4.20?
Determine the dominant acid-base equilibrium that results when each of the following pairs of solutions is mixed. Indicate the equilibrium by writing 1 for a strong acid, 3 for a weak acid, 4 for an acidic buffer, 7 for a neutral solution, 10 for a basic buffer, 11 for a weak base, and 13 for a strong base. (a) 10.0 mL of 0.15 M NaOH + 15.0 mL of 0.10 M HNO3 (b) 25.0 mL of 0.10 M HCl + 10.0 mL of 0.25 M NH3 (c) 50.0 mL of 0.050 M NaOH + 50.0 mL of 0.10 M NH3 (d) 50.0 mL of 0.10 M NH3 + 50.0 mL of 0.05 M HCl
A 10.00-g sample of the ionic compound NaA, where A is the anion of a weak acid, was dissolved in enough water to make 100.0 mL of solution and was then titrated with 0.100 M HCl. After 500.0 mL HCl was added, the pH was 5.00. The experimenter found that 1.00 L of 0.100 M HCl was required to reach the stoichiometric point of the titration. a. What is the molar mass of NaA? b. Calculate the pH of the solution at the stoichiometric point of the titration.
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