One way the U.S. Environmental Protection Agency (EPA) tests for chloride contaminants in water is by titrating a sample of silver nitrate solution. Any chloride anions in solution will combine with the silver cations to produce bright white silver chloride precipitate. Suppose an EPA chemist tests a 250. mL sample of groundwater known to be contaminated with iron(II) chloride, which would react with silver nitrate solution like this: FeCl,(aq) + 2 AgNO3(aq) → 2 AgCl(s) + Fe(NO3),(aq) The chemist adds 10.0 mM silver nitrate solution to the sample until silver chloride stops forming. He then washes, dries, and weighs the precipitate. He finds he has collected 7.7 mg of silver chloride. Calculate the concentration of iron(II) chloride contaminant in the original groundwater sample. Round your answer to 2 significant digits. mg L

12.) A 2.00g sample of limestone was dissolved in hydrochloric acid and all the calcium present in the sample was converted to Ca²+, oxalate solution, (NH,),C,O(aqo), was added to the solution to precipitate the calcium ions as calcium oxalate, CaC,O4(s). The precipitate was filtered, dried and weighed to a constant mass of 2.43g. Determine the percentage by mass of calcium in the limestone sample. Excess ammonium (aq)•

A titration is a procedure for determining the concentration of a solution by allowing it to react with another solution of known concentration (called a standard solution). Acid-base reactions and oxidation- reduction reactions are used in titrations. For example, to find the concentration of an HCl solution (an acid), a standard solution of NaOH (a base) is added to a measured volume of HCI from a calibrated tube called a buret. An indicator is also present and it will change color when all the acid has reacted. Using the concentration of the standard solution and the volume dispensed, we can calculate molarity of the HCl solution. A volume of 90.0 mL of aqueous potassium hydroxide (KOH) was titrated against a standard solution of sulfuric acid (H₂SO4). What was the molarity of the KOH solution if 13.2 mL of 1.50 M H₂SO4 was needed? The equation is 2KOH(aq) + H₂SO4 (aq)→K₂SO4 (aq) + 2H₂O(1) Express your answer with the appropriate units. ► View Available Hint(s) molarity = Submit…

To measure the amount of chlorine in a well-boring fluid, an analytical chemist adds 0.390M silver nitrate (AgNO,) solution to a 45.0 g sample of the fluid and collects the solid silver chloride (AgCl) product. When no more AgCl is produced, she filters, washes and weighs it, and finds that 1.8 g has been produced. The balanced chemical equation for the reaction is: Cl(aq) + AgNO, (aq) What kind of reaction is this? AgCl(s) + NO, (aq) If you said this was a precipitation reaction, enter the chemical formula of the precipitate. If you said this was an acid-base reaction, enter the chemical formula of the reactant that is acting as the base. If you said this was a redox reaction, enter the chemical symbol of the element that is oxidized. Calculate the mass percent of Cl in the sample. Be sure your answer has 2 significant digits. precipitation O acid-base O redox 0 0 0 0% 0° 0 0..9 X 5 A