A 1400 g sample of stream water contains 12.2 ppm of mercury (Hg). What is the mass of Hg present in the sample?

• A. 0.12 g
• B. 1.22 g
• C. 0.0171 g
• D. 0.00122 g

Answer: (C)

Verified step by step guidance

1. Understand that ppm (parts per million) means milligrams of solute per kilogram of solution. Specifically, 1 ppm = 1 mg of solute per 1 kg of solution.
2. Convert the mass of the water sample from grams to kilograms because ppm is based on kilograms: \(\text{mass in kg} = \frac{1400\, \text{g}}{1000}\).
3. Use the definition of ppm to find the mass of mercury: \(\text{mass of Hg (mg)} = \text{ppm} \times \text{mass of sample (kg)}\).
4. Calculate the mass of mercury in milligrams using the given ppm value of 12.2 and the mass of the sample in kilograms.
5. Convert the mass of mercury from milligrams to grams by dividing by 1000 to get the final mass of Hg in grams.