Use a calculation based on the pH partition model to determine the likelihood that a weakly acidic drug of pKa= 3.0 will be absorbed passively from the stomach (pH = 2.3) or from the small intestine (pH = 5.0). The pH of the blood is 7.4 .

Consider a buffer solution of acetate. The volume is 500 ml, the concentration is 200 mM, and the pH is 5.0. a. How many total moles of acetate plus acetic acid are present in the solution? Express answer as x.y with one digit before and one after the decimal place. b. What is the ratio of acetate ions (Ac-) to acetic acid ions (HAc) in the buffer solution (pH 5.0) if the pka is 4.76? Express the answer as x.yz with one digit before and two after the decimal place. c. How many moles of acetate are present in the solution? Express your answer to one decimal place. d. How many moles of acetic acid are present in the solution? Express your answer to one decimal place.

The glass electrode used in commercial pH meters gives an electrical response proportional to the concentration of hydrogen ion. To convert these responses to a pH reading, the electrode must be calibrated against standard solutions of known H+ concentration. Determine the weight in grams of sodium dihydrogen phosphate (NaH2PO4 · H2O; FW 138) and disodium hydrogen phosphate (Na2HPO4 ; FW 142) needed to prepare 1 L of a standard buffer at pH 7.00 with a total phosphate concentration of 0.100 M . See Problem 24 for the pKa values of phosphoric acid.

What is the approximate rate of change of A340 measured? i.e.  ΔA340  / min =  __________ What rate of change of A340 would you predict if 30 ml of the ADH solution was tested in the same way (i.e. half the amount of protein) ? i.e.  ΔA340  / min =   __________ What rate of change of A340 would you predict if 60 ml of a 0.5 μM ADH solution was tested in the same way? i.e.  ΔA340  / min =   __________ As well as writing your answers, explain your reasoning.