Problem: Papaverine hydrochloride (abbreviated papH+Cl-; molar mass = 378.85 g/mol) is a drug that belongs to a group of medicines called vasodilators, which cause blood vessels to expand, thereby increasing blood flow. This drug is the conjugate acid of the weak base papaverine (abbreviated pap; Kb = 8.33 X 10 -9 at 35.0°C). Calculate the pH of a 30.0-mg/mL aqueous dose of papH+Cl- prepared at 35.0°C. K w at 35.0°C is 2.1 X 10 -14.

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FREE Expert Solution

Step 1

[HA] =30 mg ×10-3 g1 mg×1 mol378.85 g1 mL ×10-3 L1 mL = 0.0792 M

Step 2


Step 3

Ka = 2.1×10-148.33×10-9 = 2.521x10-6


Step 4

Ka =[A-][H3O+][HA]Ka =(x)(x)0.0792 - x


[HA]Ka=0.07922.521×10-6>>> 500


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Problem Details

Papaverine hydrochloride (abbreviated papH+Cl-; molar mass = 378.85 g/mol) is a drug that belongs to a group of medicines called vasodilators, which cause blood vessels to expand, thereby increasing blood flow. This drug is the conjugate acid of the weak base papaverine (abbreviated pap; Kb = 8.33 X 10 -9 at 35.0°C). Calculate the pH of a 30.0-mg/mL aqueous dose of papH+Cl- prepared at 35.0°C. K w at 35.0°C is 2.1 X 10 -14.