What is the maximum amount of Hg (in μg ) that can be present in this 10.0 mL sample based on its MCL?

Question

The maximum contaminant level (MCL) set by the EPA of mercury in drinking water is 0.0020 mg/L0.0020 mg/L . Convert the MCL of mercury from milligrams per liter to parts per billion (ppb).

converted MCL of mercury: 2.0 ppb

A farmer recently dug a new well for his property. He sends a 10.0 mL sample of the well water to the EPA to be tested for the presence of mercury. What is the maximum amount of Hg (in μg ) that can be present in this 10.0 mL sample based on its MCL?

Maximum amount of Hg:

Need help with 2nd part/ maximum amount of Hg :(

Answer 1

By definition: 2.0 ppb is 2.0 units of solute mass per x 10⁶ unit of mass of solution

since the mass of solute is so so so small compare to that of the solvent,

we can rewrite the above definition as:

2.0 ppb is 2.0 units of solute mass per x 10⁶ unit of mass of solvent.

Given density of water is 1.0 g per each mL, Now we can setup ratio equation to solve problem.

1000 x 1000 mL : 2 g = 10.0 mL : ? g

Rearrange and simplify to get

106 / 2 g = 10.0 /? g

solve the equation and get ? = 2.00 x 10^-5

So, the maximum amount of mercury this sample of 10.0 ml is 2.00 x 10^-5 g or 0.0000200 g. //answer