Drinking water may contain a low concentration of lead ion (Pb2) due to corrosion of old lead pipes. The EPA has determined that the maximum safe level of lead ion in water is 15 ppb. Suppose a sample of tap water was determined to have a lead ion concentration of 0.0080 ppm. Assume the density of the solution is 1.00 g/mL. How many moles of lead ion are in 100.0 mL of the water

Question

Ronin Mullins

Chemistry

25 May, 02:23

Drinking water may contain a low concentration of lead ion (Pb2) due to corrosion of old lead pipes. The EPA has determined that the maximum safe level of lead ion in water is 15 ppb. Suppose a sample of tap water was determined to have a lead ion concentration of 0.0080 ppm. Assume the density of the solution is 1.00 g/mL. How many moles of lead ion are in 100.0 mL of the water

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Sharon Choi · Answer 1

3.861x10⁻⁹ mol Pb⁺²

Explanation:

We can define ppm as mg of Pb²⁺ per liter of water.

We calculate the mass of lead ion in 100 mL of water:

100.0 mL ⇒ 100.0 / 1000 = 0.100 L 0.100 L * 0.0080 ppm = 8x10⁻⁴ mg Pb⁺²

Now we convert mass of lead to moles, using its molar mass:

8x10⁻⁴ mg ⇒ 8x10⁻⁴ / 1000 = 8x10⁻⁷ g 8x10⁻⁷ g Pb²⁺ : 207.2 g/mol = 3.861x10⁻⁹ mol Pb⁺²