Question

The level of mercury in a stream was suspected to be above the minimum considered safe (1part per million by weight). An analysis indicated that the concentration was 0.68 parts per million .Assume a density of 1.0 g/ml and calculate the molarity of mercury is the stream.

Answer 1

[Hg] = 3.4 x 10⁻⁶ M

Step-by-step explanation:

Parts per million (ppm) is defined as (1 g solute) / (10⁶ g solution), or (10⁻⁶g solute) / (g solution). Here the density of the stream is 1.0 g/mL, so ppm is equal to 10⁻⁶g/mL.

The atomic mass of mercury is 200.59 g/mol, so the molarity is calculated as follows:

0.68ppm = (0.68 x 10⁻⁶g)/mL x (1000mL/L) x (mol/200.59g) = 3.4 x 10⁻⁶ M