Environmental Measurements Homework 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)?
- For a water sample that contains nitrate, NO
_{3}, at 10 mg/L as N, what is the nitrate concentration as NO_{3}? - How many grams of calcium carbonate, CaCO
_{3}, are there in 175 mL of 1.5% solution? You can assume that the density of the solution is 1 g/mL. - How many grams of sodium hydroxide, NaOH, in 200 mL of a 1.0 M (molar) solution?

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

- Concentrated nitric acid contains 70 percent (mass/mass) HNO
_{3}dissolved in water and has a density of 1.38 g/mL. - What is the molarity (M)(mol/L) of concentrated nitric acid?
- How many milliliters of concentrated nitric acid would you need to make 200 mL of 6 M nitric acid?
- How many grams of nitrogen are contained in one liter of concentrated nitric acid?
- 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?
- 0.10 g of disodium hydrogen phosphate (Na
_{2}HPO_{4}· 2H_{2}O) is dissolved in 100 mL of water.

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