Environmental Measurements Homework 1

1. 0.75 g of paint was extracted with nitric acid and the extract was diluted to 100 mL. The diluted extract contained 110 mg/L of lead. What was the original lead content of the paint in percent (g per 100 g)?
2. For a water sample that contains nitrate, NO₃, at 10 mg/L as N, what is the nitrate concentration as NO₃?
3. How many grams of calcium carbonate, CaCO₃, are there in 175 mL of 1.5% solution? You can assume that the density of the solution is 1 g/mL.
4. How many grams of sodium hydroxide, NaOH, in 200 mL of a 1.0 M (molar) solution?

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ENV 1221 Additional Homework Problems (note: chemical data given here is not necessarily accurate).

1. Concentrated nitric acid contains 70 percent (mass/mass) HNO₃ dissolved in water and has a density of 1.38 g/mL.
1. What is the molarity (M)(mol/L) of concentrated nitric acid?
2. How many milliliters of concentrated nitric acid would you need to make 200 mL of 6 M nitric acid?
3. How many grams of nitrogen are contained in one liter of concentrated nitric acid?
4. 9.0 g of concentrated nitric acid is diluted to 100 mL. What is the concentration of the solution in mol/L and mg/L?
2. 0.10 g of disodium hydrogen phosphate (Na₂HPO₄· 2H₂O) is dissolved in 100 mL of water.

1. How many mol/L of disodium hydrogen phosphate in the solution?
2. How many mol/L of sodium?
3. How many mg/L of phosphorus does this solution contain?
4. How many milliliter of this solution should be diluted to 100 mL to make a solution that contains 10 mg/L of phosphorus?

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