Morphine, C₁₇H₁₉NO₃, is often used to control severe post-operative pain. What is the pH of the solution made by dissolving 25.0 mg of morphine in 100. mL of water? (For morphine, K_b = 1.62 * 10^-6.) A) 9.57 B) 9.08 C) 3.79 D) 9.87 E) 4.43

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The correct answer is A because the pH of the solution is 9.57. Morphine is a weak base, so it will react with water to form hydroxide ions. The equilibrium constant for this reaction is Kb = 1.62 * 10^-6. We can use this equilibrium constant to calculate the concentration of hydroxide ions in the solution.[OH-] = Kb * [Morphine] / [H+][OH-] = 1.62 * 10^-6 * (25.0 mg / 100. mL) / (1.0 * 10^-7 M)[OH-] = 4.05 * 10^-5 MNow we can use the pOH of the solution to calculate the pH.pOH = -log[OH-]pOH = -log(4.05 * 10^-5)pOH = 4.39pH = 14 - pOHpH = 14 - 4.39pH = 9.57

Morphine, C17H19NO3, Is Often Used to Control Severe Post-Operative Pain

Morphine, C₁₇H₁₉NO₃, Is Often Used to Control Severe Post-Operative Pain