The concentration of iodine in sea water is 60. parts per billion by mass. If one assumes that the iodine exists in the form of iodide anions, what is the molarity of iodide in sea water? (The density of sea water is 1.025 g/mL.)

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Quizplus · Accepted Answer

To find the molarity, convert parts per billion (ppb) to grams per liter using the density of sea water, then divide by the molar mass of iodide (I⁻, approximately 127 g/mol). 60 ppb is 60 mg per 1000 kg of water, which is 60 mg per 1000 L (since 1 kg of water is approximately 1 L). Convert 60 mg to grams (0.060 g), then divide by the molar mass to find moles, and divide by the volume in liters to find molarity: (0.060 g / 127 g/mol) / 1 L = 4.8 × 10⁻⁷ M.

The Concentration of Iodine in Sea Water Is 60