Prepare ~ 8.75 × 10–4 M K2CrO4 solution from the ~1.25× 10–3 M K2CrO4 stock solution.  Record the exact molarity of the stock solution. Calculate the required amount of stock solution to make 10.00 mL of dilute solution.   Adjust this value as necessary (ratio) based on the volumetric flask available.

Fluoridation of city water supplies has been practiced in the United States for several decades. It is done by continuously adding sodium fluoride to water as it comes from a reservoir. Assume you live in a medium-sized city of 150,000 people and that 660 L (170 gal) of water is used per person per day. What mass of sodium fluoride (in kilograms) must be added to the water supply each year (365 days) to have the required fluoride concentration of 1 ppm (part per million)that is, 1 kilogram of fluoride per 1 million kilograms of water? (Sodium fluoride is 45.0% fluoride, and water has a density of 1.00 g/cm3.)

Calcium carbonate, CaCO3, can be obtained in a very pure state. Standard solutions of calcium ion are usually prepared by dissolving calcium carbonate in acid. What mass of CaCO3 should be taken to prepare 500. mL of 0.0200 M calcium ion solution?

For each of the following pairs of solutions, select the solution for which solute solubility is greatest. a. Ammonia gas in water with P = 1 atm and T = 50C Ammonia gas in water with P = 1 atm and T = 90C b. Carbon dioxide gas in water with P = 2 atm and T = 50C Carbon dioxide gas in water with P = 1 atm and T = 50C c. Table salt in water with P = 1 atm and T = 60C Table salt in water with P = 1 atm and T = 50C d. Table sugar in water with P = 2 atm and T = 40C Table sugar in water with P = 1 atm and T = 70C