The active volcano Mauna Loa, in Hawaii, and the now-extinct volcano Ei Yunque. Puerto Rico, have certain basaltic lava rocks containing the element selenium. Typically, a 25-g rock contains 0.005 g of selenium. What is the concentration of selenium in these lava rocks, in ppm?

Answer 1

To calculate the concentration of selenium in these lava rocks in parts per million (ppm), we can use the formula:

Concentration (ppm) = (Mass of selenium in rock / Mass of rock) * 1,000,000

Given:
Mass of selenium in rock = 0.005 g
Mass of rock = 25 g

Plugging in the values:

Concentration (ppm) = (0.005 g / 25 g) * 1,000,000
Concentration (ppm) = (0.0002) * 1,000,000
Concentration (ppm) = 200 ppm

Therefore, the concentration of selenium in these lava rocks is 200 ppm.