GRAVIMETRIC ANALYSIS PROBLEMS - EXERCISES IN STOICHIOMETRY
1. In the analysis of 0.7011 g of an impure chloride containing sample, 0.9805 g of AgCl were
precipitated. What is the percentage by mass chloride in the sample?
2. A 0.4054 g solid organic sample containing covalently bound bromide and no other halogens
was placed in a porcelain crucible with about one gram of fresh sodium metal. In a process
known as sodium fusion, the mixture was heated in a furnace to 450°C which charred and
vaporized the organic portion of the molecule and converted the covalent bromide into
sodium bromide. Excess sodium was decomposed by adding small portions of water which
also dissolved the sodium bromide. The clear solution was quantitatively transferred to a
beaker, acidified with dilute nitric acid, and diluted to about 50 mL. A 6 mL quantity of 0.1
M AgNO3 was added to the solution and the mixture heated to about 60°C for an hour to age
and digest the precipitate. After filtering, the mass of the silver bromide produced was
determined to be 37.8 mg. What is the percentage by mass bromine in the organic
compound?
