Question

What is the concentration in ppb of selenium if 1.3 milligrams are found in 2500 kg of soil?

a) 0.52 ppb
b) 0.26 ppb
c) 0.65 ppb
d) 0.39 ppb

Answer 1

The concentration of selenium is calculated by converting the mass of the solute and solution into compatible units (grams), and then using the formula for ppb, resulting in a concentration of 0.52 ppb.

Step-by-step explanation:

To calculate the concentration in ppb of selenium if 1.3 milligrams are found in 2500 kg of soil:

• First, understand that ppb means parts per billion, which is equivalent to the number of grams of solute per one billion grams of solution.
• Next, convert kilograms of soil to grams because ppb is based on grams. So, 2500 kg is equal to 2,500,000 grams.
• Then, since 1 mg = 0.001 g, convert the mass of selenium from milligrams to grams: 1.3 mg is equivalent to 0.0013 g.
• Using the formula for ppb, which is (mass of solute in grams/mass of solution in grams) x 109, we calculate the concentration: (0.0013 g / 2,500,000 g) x 109 ppb.
• Therefore, the concentration is 0.52 ppb.