A beaker contains aqueous solutions of calcium and barium nitrates. Aqueous sodium carbonate is added to the beaker, and a precipitate forms. What is the composition of the precipitate?

Fluoridation of drinking water is employed in many places to aid in the prevention of tooth decay. Typically. the Fion concentration is adjusted to about 1 ppm. Some water supplies are also 'hard'; that is, they contain certain cations such as Ca2 + that interfere with the action of soap. Consider a case where the concentration of Ca2 + is 8 ppm. Could a precipitate of CaF2 form under these conditions? (Make any necessary approximations.)