Final answer:
The concentration of mercury in a polluted lake would typically be expressed in parts per million (ppm) or parts per billion (ppb), depending on the level of pollution and the precision required.
Step-by-step explanation:
The concentration of mercury in a polluted lake is typically measured in parts per million (ppm) or parts per billion (ppb). These units express the ratio of the amount of mercury relative to the total weight or volume of the water in the lake. For very low concentrations, such as with pollutants in water, ppb is often the preferable unit as it allows for the expression of extremely small quantities, thus capturing the minute scale of the pollutant levels.
To convert a mass of mercury in milligrams to ppm or ppb in a given sample, the mass of mercury (in milligrams) is compared to the mass of the water sample (in grams). The concentration in ppm is calculated as the mass of the mercury divided by the mass of the water sample, multiplied by a million. Similarly, for ppb, the mass of mercury is divided by the mass of the water sample and then multiplied by a billion.For example, if a 50.0-g sample of industrial wastewater contained 0.48 mg of mercury, the concentration would be (0.48 mg / 50.0 g) × 1,000,000 = 9.6 ppm. For ppb, it would be (0.48 mg / 50.0 g) × 1,000,000,000 = 9,600 ppb.The unit of measurement typically used to express the concentration of mercury in a polluted lake is parts per million (ppm) or parts per billion (ppb). In the given example, the concentration of mercury in the industrial wastewater is expressed in both ppm and ppb units. To convert from mg to ppm, divide the mass of mercury by the mass of the solution and multiply by 10^6. To convert to ppb, further multiply the result by 1000.