1) He prepared 2.00 g of iron sulfide A, which he then dissolved in aqua regia. He added BaCl2 solution to precipitate 5.38 g of BaSO4. He treated the iron remaining in solution, converting it to 1.82 g of red iron oxide, Fe2O3.
a) Use a modern periodic table to compute the percent sulfur in BaSO4.
b) What is the mass of sulfur in 5.38 g BaSO4?
c) This sulfur came from the 2.00 g sample of iron sulfide A. What is the percent sulfur by mass in iron sulfide A?
d) How many moles of sulfur were in the sample of iron sulfide A?
e) Use a modern periodic table to compute the percent iron in Fe2O3.
f) What is the mass of iron in 1.82 g Fe2O3?
g) This iron came from the 2.00 g sample of iron sulfide A. What is the percent iron by mass in iron sulfide A?
h) How many moles of iron were in the sample of iron sulfide A?
i) A compound's empirical formula is the ratio of moles of its elements expressed in small whole numbers. What is the empirical formula of iron sulfide A?
2) He extracted 9.93 g of iron sulfide B from a natural sample of the mineral pyrite. This iron sulfide sample B contained 4.58 g iron and 5.35 g sulfur.
a) How many moles of sulfur were in the sample of iron sulfide B?
b) How many moles of iron were in the sample of iron sulfide B?
c) What is the empirical formula of iron sulfide B?
3) Let us compare the compositions of two iron sulfides by mass, forgetting for a moment about moles and formulas.
a) What is the mass of sulfur that would combine with 1.00 g of iron to yield iron sulfide A?
b) What is the mass of sulfur that would combine with 1.00 g of iron to yield iron sulfide B?
c) What is the relationship between these masses?
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