Solutions: Mass Percent Practice Problems

An evaporating dish with a mass of 42.6 g was used to hold a 20 mL FeSO₄ solution. The mass of the evaporating dish with the solution is 68.5 g. The solution was heated to remove all the water, and the final mass of the evaporating dish and the dry FeSO₄ was 48.5 g. Calculate the mass percent of the original FeSO₄ solution.

The solubility of KHSO₄ at 25°C and 60°C are given in the table below. A solution was made by dissolving 105. g of KHSO₄ in 150 g of H₂O at 60°C. If this solution was cooled to 25°C, determine the mass of solid KHSO₄ that precipitated out after cooling.

Refer to the information given in the table below. A solution was prepared by dissolving 350. g of LiClO₄ in 400. g of H₂O at 60°C. If the solution was cooled to 30°C then agitated, calculate the mass of LiClO₄ left in the solution.

One way to express a concentration of a solution is by using volume/volume percent concentration. Define volume/volume percent concentration and determine the type of solutions in which it is used.

Hydrochloric acid is used to neutralize the ammonia produced from a Kjeldahl method where all nitrogen organic substances are converted to ammonia. In a 4.37 g sample of organic material, 23.0 mL of 0.280 M HCl (aq) was used up. Determine the mass percentage of nitrogen in the sample.

NH₃(aq) + HCl(aq) → NH₄Cl(aq)

A solution is prepared by dissolving 11.00 grams of benzoic acid (molar mass = 122.12 g/mol) in 211 grams of water. It has a density of 1.26 g/mL.

a. Calculate the % mass of the solution

b. Calculate the molarity of the solution

c. Calculate the molality of the solution