c 03 pt Which one or two species isare controlling pH assuming the solution was

# C 03 pt which one or two species isare controlling ph

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(c) (0.3 pt) Which one or two species is(are) controlling pH, assuming the solution was prepared from the two fully protonated species, as indicated in the problem? What pH would result from this mixture? The two species are: and pH = 7. (0.5 pt)
8. (0.8 pts) Calculate the pH of a solution of 0.0030 M potassium arsenite, KH 2 AsO 3 . The conjugate weak acid of the arsenite ion, H 3 AsO 3 has K a = 5.1 x 10 −1 0 . (It only has one acidic H in water.) pH= 9.(a) (0.4 pts) Citric acid is a triprotic weak acid with pK a 's = 3.13, 4.76 and 6.40. Let H 3 Cit represent the fully protonated form, and circle the conjugate acid/base pair below that should be chosen for a buffer at pH = 4.65. Circle one : H 3 Cit / Cit 3 ̶ H 2 Cit ̶ / HCit 2 ̶ HCit 2 ̶ / Cit 3 ̶ H 3 Cit/ HCit 2 ̶ H 3 Cit / H 2 Cit ̶ (b) (0.5 pts) Calculate ratio of conjugate base-to-conjugate acid to prepare the pH 4.65 buffer in part (a). Ratio = (c) (0.7 pt) If the ionic strength of the buffer solution has to be 0.0250 M, then what are the required concentrations of the conjugate acid and base forms? Acid form Base form
10. A solid sample (1.3934 g) of impure weak acid is dissolved in 50.00 mL water and titrated with NaOH ( 0.1107 M). The equivalence point occurs at 43.25 mL. At this point, pH = 8.79. The weak acid has a molar mass of 244.17 g/mol a) (0.5 pt) What is the % (wt/wt) of the weak acid in the impure solid sample? % (wt/wt) in original sample = b) (0.5 pt) What is K a for this weak acid? K a =
11. (1 pts) A biochemical reaction is to be carried out in 250.00 mL solution and buffered to physiologic pH of 7.20 using a conjugate acid/base pair, pK a = 6.98. Because of the fragility of the proteins involved and their limited solubility, the pH must not change by more than + 0.05 pH units during the reaction. What must the concentration be, of each member of the buffering

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• Fall '15
• DaleRussel

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