Verapamil is used to treat certain heart conditions, including high blood pressure and arrhythmia. Studies continue on the factors that affect the drug’s absorption into the body. The article “The Effect of Nonionic Surfactant Brij 35 on Solubility and Acid-Base Equilibria of Verapamil” (J. Chem. Engr. Data 2017: 1776–1781) includes the following data on x = pH and y = Verapamil solubility (10⁻⁵ mol/L) at 25 °C for one such study.

a. Construct a scatterplot of solubility versus pH, and describe what you see. Does it appear that a linear model would be appropriate here?
b. Hydrogen ion concentration [H⁺] is related to pH by pH = –log₁₀([H⁺]). Use this to calculate the hydrogen ion concentrations for each observation, then make a scatterplot of solubility versus [H⁺]. Does it appear that a linear model would fit this data well?

c. Would a linear function fit the data in part (b) perfectly? That is, is it reasonable to assume a completely deterministic relationship here? Explain your reasoning.

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pH 8.12 sol. 53.4 8.32 8.41 8.62 8.88 9.09 22.2 14.6 13.9 8.76 5.06 5.57 32.3 8.70 8.84