solve question 35 without using the hasselbalch equation. show all work Exercise
ID: 697609 • Letter: S
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solve question 35 without using the hasselbalch equation. show all work
Exercises 737 I) 30. Calculate the pH after 0.10 mol NaOft is added to 1.00 L of the solution in Exercise 28, and calculate the pH after 0.20 mol HCi is added to 1.00 L of the solution in Exercise 28 gi nd 31. Calculate the pH of each of the following buffered solutions. a. 0.10 M acetic acid/0.25 M sodium acetate b. 0.25 M acetic acid/o.10 M sodium acetate c. 0.080 M acetic acid/0.20 M sodium acetate d. 0.20 M acetic acid/0,080 M sodium acetate 32. Calculate the pH of each of the following buffered solutions. a. 0.50 M C,H,NH/0.25 M C,H,NH,C b. 0.25 M C,H,NH,/0.50 M C HsNH CI c. 0.50 M C,H,NH,/0.50 M C,H NH,CI in 33. Calculate the pH of a buffer solution prepared by dissolving 1.5 g benzoic acid (HC,H,O,) and 37.7 g sodium benzoate in 200.0 mL of solution 34. A buffered solution is made by adding 50.0 g NH,CI to 1.00 I of a 0.75 M solution of NH3. Calculate the pH of the final ution. (Assume no volume change.) 35. Calculate the pH after 0.010 mol gaseous HCI is added to 250.0 mL of each of the following buffered solutions a. 0.050 M NH,/0.15 M NH,CI b. 0.50 M NH,/1.50 M NH,CI Do the two original buffered solutions differ in their pH or their capacity? What advantage is there in having a buffer with a greater capacity? 36. An aqueous solution contains dissolved C&H;,NH,Cl and C,H,NH2 The concentration of C,H,NH2 is 0.50 M and pH is 4.20 a. Calculate the concentration of CH&NH3; in this buffer solution b. Calculate the pH after 4.0 g NaOH(s) is added to 1.0 L of this solution. (Neglect any volume change.) 37. Calculate the mass of sodium acetate that must be added to 500.0 mL of 0.200 M acetic acid to form a pH = 5.00 buffer solution. 38. What volumes of 0.50 M HNO2 and 0.50 M NaNO2 must be mixed to prepare 1.00 L of a solution buffered at pH 3.55? 39. Consider a solution that contains both C$H;N and CH,NHNO Calculate the ratio [C,HsN]/[C,HgNH ] if the solution has the following pH values a, pH = 4.50 c, pH = 5.23 b, pH=5.00 d, pH-5.50 40. Calculate the ratio [NHJ/[NH, ] in ammonia/ammonium chlo- a, pH = 9.00 b, pH = 8.80 ns with the following pH values: c, pH = 10.00 d, pH = 9.60 41. Consider the acids in Table 14.2. Which acid would be the best choice for preparing a pH = 7.00 buffer? Explain how to makeExplanation / Answer
a. no of mol of NH3 in the buffer = V*M = 0.25*0.05 = 0.0125 mol
no of mol of NH4Cl = 0.15*0.25 = 0.0375 mol
no of mol of HCl added = 0.01 mol
pH = pka + log(NH3-HCl/NH4Cl+HCl)
pka of NH3 = 9.3
pH = 9.3 + log((0.0125-0.01)/(0.0375+0.01))
= 8
b.
no of mol of NH3 in the buffer = V*M = 0.25*0.5 = 0.125 mol
no of mol of NH4Cl = 1.5*0.25 = 0.375 mol
no of mol of HCl added = 0.01 mol
pH = pka + log(NH3-HCl/NH4Cl+HCl)
pka of NH3 = 9.3
pH = 9.3 + log((0.125-0.01)/(0.375+0.01))
= 8.77
buffer with greater capacity,result greater resistance to change in pH by the addition of acid/base.
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