Testbank, Question 7 Two buffer solutions of the same pH are prepared. After adding 15 millimoles of acid to 250 mL of one solution, the pH changes by 0.02 pH unit. Adding 15 millimoles of acid to 250 mL of the second solution results in a 0.05 pH unit change. Which statement most accurately describes the differences between the two buffer solutions? O The second solution has a lower concentration of coniugate base that the firet colution

Testbank, Question 7 Two buffer solutions of the same pH are prepared. After adding 15 millimoles of acid to 250 mL of one solution, the pH changes by 0.02 pH unit. Adding 15 millimoles of acid to 250 mL of the second solution results in a 0.05 pH unit change. Which statement most accurately describes the differences between the two buffer solutions? O The second solution has a lower concentration of coniugate base that the firet colution

Chemistry

10th Edition

ISBN:9781305957404

Author:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste

Publisher:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste

Chapter15: Acid-base Equilibria

Section: Chapter Questions

Problem 2ALQ: A friend asks the following: Consider a buffered solution made up of the weak acid HA and its salt...

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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)?
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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?
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