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H-A is an acid with a pKa of 4.5. Which of the following statements about an aqu

ID: 538217 • Letter: H

Question

H-A is an acid with a pKa of 4.5. Which of the following statements about an aqueous solution of H-A is true? ________ At pH = 6.5, the solution contains about 80% A-and 20% H-A. At pH = 5.5, the solution contains about 90% A-and 10% H-A. At pH = 3.5, the solution contains about 90% A-and 10% H-A. At pH = 4.5, the solution contains much more H-A than. A-. At pH = 4.5, the solution contains much more A- than H-A. Buffering is used to maintain the pH of human blood in the relatively narrow 7.3 - 7.4 range. What acid/base pair serves to buffer the blood? H_2CO_3/HCO_3^- H_3O^+/H_2O H_2O/HO^- HCI/CI^- NH_4^+/NH_3 ________ What would be the conjugate acid in the following acid base reaction? CH_3O^- + CH_3SH CH_2O CH_3S^- CH_3SH_2^+ CH_3OH H_2O ______

Explanation / Answer

28. Correct option is B, since a/c to pH = pKa + log con. of A-/conc. of HA, and we get pH = 5.45 .

29. Correct option A, bicarbonate and carbonic acid maintains pH of blood between 7.35-7.45.

30. Option D, here CH3O- is base and it's conjugate acid should be CH3OH.

Conjugate acid -base pair means different in one proton.