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Using Henry's law and the data in the introduction, calculate the molar concentration of Og in the surface water of a mountain lake saturated with air at 20 C and an atmospheric pressure of 685 torr Express the molar concentration to two significant figures. V AC ? [02] = M The partial pressure of O2 in air at sea level is 0.21 atm. The solubility of O2 in water at 20C, at 1 atm gas pressure, is 1.38 x 10-3 M (from Table 13.1 in your textbook)