Concentration of calcium in a sample may be determined by precipitation using the chromate ion, CrO2−4.   Ca2+(aq)+CrO2−4(aq)⟶CaCrO4(s)   A chemist combined 0.290 L of an unknown calcium solution with an excess of ammounium chromate. This resulted in the precipitation of calcium chromate. The mass of the precipitate was 286.3 mg. What was the molar concentration of Ca2+

The traditional method of analysis for the amount of chloride ion present in a sample is to dissolve the sample in water and then slowly to add a solution of silver nitrate. Silver chloride is very insoluble in water, and by adding silver nitrate, it is possible effectively to remove all chloride ion from the sample. Ag+(aq) + Cl-(aq) → AgCl(s) Suppose a 1.515 g sample is known to contain 27.5% chloride ion by mass. What mass of silver nitrate must be used to completely precipitate the chloride ion from the sample?

Fe(II) can be precipitated from a slightly basic aqueous solution by bubbling oxygen through the solution, which converts Fe(II) to insoluble Fe(III): $$4Fe(OH)+(aq)+4OH−(aq)+O2​(g)+2H2​O(l)4Fe(OH)3​(s)  How many grams of O2 are consumed to precipitate all of the iron in 75.0 mL of 0.0350 M Fe(II)?

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