I. Observing pH Changes in Water and Buffer Solutions upon Addition of HCl and NaOH Solutions solution calculated pH measured pH theoretical (H30*] distilled water original buffer solution distilled water with added 6M HCI buffer solution with added 6M HCI distilled water with added 6M NaOH buffer solution with added 6M NAOH

I. Observing pH Changes in Water and Buffer Solutions upon Addition of HCl and NaOH Solutions solution calculated pH measured pH theoretical (H30*] distilled water original buffer solution distilled water with added 6M HCI buffer solution with added 6M HCI distilled water with added 6M NaOH buffer solution with added 6M NAOH

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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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 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?
Enough water is added to the buffer in Question 30 to make the total volume 5.00 L. (a) Calculate the pH of the buffer. (b) Calculate the pH of the buffer after adding 0.0250 mol of HCl to 0.376 L of the buffer. (c) Calculate the pH of the buffer after adding 0.0250 mol of KOH to 0.376 L of the buffer. (d) Compare your answers to Question 30 (a-c) with your answers to (a-c) of this problem. (e) Comment on the effect of dilution on the pH of a buffer and on its buffer capacity. Â
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 monoprotic organic acid that has a molar mass of 176.1 g/mol is synthesized. Unfortunately, the acid produced is not completely pure. In addition, it is not soluble in water. A chemist weighs a 1.8451-g sample of the impure acid and adds it to 100.0 mL of 0.1050 M NaOH. The acid is soluble in the NaOH solution and reacts to consume most of the NaOH. The amount of excess NaOH is determined by titration: It takes 3.28 mL of 0.0970 M HCl to neutralize the excess NaOH. What is the purity of the original acid, in percent?
Enough water is added to the buffer in Question 29 to make the total volume 10.0 L. Calculate (a) the pH of the buffer. (b) the pH of the buffer after the addition of 0.0500 mol of HCl to 0.600 L of diluted buffer. (c) the pH of the buffer after the addition of 0.0500 mol of NaOH to 0.600 L of diluted buffer. (d) Compare your answers to Question 29(a)-(c) with your answers to (a)-(c) in this problem. (e) Comment on the effect of dilution on the pH of a buffer and on its buffer capacity.
A buffer solution contains dissolved C6H5NH2 and C6H;NH3CI. The initial concentration of C6H5NH2 is 0.50 M and the pH of the buffer is 4.20. Determine the concentration of C6H5NH3* in the solution. The value of Kb for C6H5NH2 is 3.8 x 10 10. ( PREV 1 3 NEXT > Based on your ICE table and definition of Kb, set up the expression for Kb in order to determine the unknown. Do not combine or simplify terms. Kp 3.8 x 10-10 %3D %3D 5 RESET [0] [0.50] [x] [2x] [4.20] [6.3 x 10-5) [1.6 x 10-10] [3.8 х 1011 [x + 4.20] [x - 4.20] [x + 6.3 x 10-51 [x - 6.3 х 10-5] [x + 1.6 x 101°] [x - 1.6 x 10-10] [x + 3.8 x 10-101 [x - 3.8 x 101°]
4. A pH buffer solution contains 1.383 mole CH3COOH and 1.875 mole CH3COONa. The volume of the pH buffer solution is 250.0 mL. The acid dissociation constant of CH3COOH is 1.799x10-5. Please answer the following questions. A B. C. What is the pH of the solution? pH = Your answer follows. If you add 5.000 mL, 1.431 M of HCl to 250.0 mL above solution you prepared, what will be the final pH? Assume that the volume is additive. Your answer follows. If you add 5.000 mL, 1.431 M of Ba(OH)2 to 250.0 mL above solution you prepared, what will be the final pH? Assume that the volume is additive.