91Ó°ÊÓ

The beryllium mineral beryl is made up of \(5.03 \%\) by mass Be, \(10.04 \%\) by mass Al, \(31.35 \%\) by mass \(\mathrm{Si}\), and \(53.58 \%\) by mass \(\mathrm{O}\). If the molar mass is approximately \(538 \mathrm{~g} / \mathrm{mol}\), what is the molecular formula for beryl?

Consider the unbalanced chemical equation \(\mathrm{S}+\mathrm{H}_{2} \mathrm{SO}_{4} \rightarrow \mathrm{SO}_{2}+\mathrm{H}_{2} \mathrm{O}\) (a) Balance the equation. (b) If you react \(4.80 \mathrm{~g}\) of sulfur with \(16.20 \mathrm{~g}\) of \(\mathrm{H}_{2} \mathrm{SO}_{4}\), how many grams of \(\mathrm{SO}_{2}\) can theoretically be produced?

In a chemical reaction, the mass of the products is equal to the mass of the reactants consumed. Are the moles of product equal to the moles of reactant consumed? Explain your answer.

Some calcium supplements contain calcium citrate, \(\mathrm{Ca}_{3}\left(\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{O}_{7}\right)_{2}\), and others contain calcium carbonate, \(\mathrm{CaCO}_{3}\). Which compound has the higher mass percent of calcium?

Copper reacts with nitric acid as shown in the balanced chemical equation \(3 \mathrm{Cu}+8 \mathrm{HNO}_{3} \rightarrow 3 \mathrm{Cu}\left(\mathrm{NO}_{3}\right)_{2}+2 \mathrm{NO}+4 \mathrm{H}_{2} \mathrm{O}\) If you react \(25.0 \mathrm{~g}\) of copper with an excess of nitric acid and produce \(7.24 \mathrm{~g}\) of \(\mathrm{NO}\), what is the percent yield for the reaction?

How many molecules of aspirin, \(\mathrm{C}_{9} \mathrm{H}_{8} \mathrm{O}_{4}\), would be in a tablet that contained \(250 \mathrm{mg}\) of aspirin? How many atoms of carbon would be in the aspirin in that tablet?

Calcium reacts with nitrogen gas to form calcium nitride. If \(33.8 \mathrm{~g}\) of calcium react with \(20.4 \mathrm{~g}\) of nitrogen gas, (a) Which reactant is the limiting reagent? (b) If the reaction has a \(72.4 \%\) yield, how many grams of calcium nitride are formed?

Calcium hydroxide reacts with phosphoric acid to produce calcium phosphate and water. (a) How many grams of phosphoric acid are needed to react completely with \(34.6 \mathrm{~g}\) of calcium hydroxide? (b) How many grams of calcium phosphate would theoretically be produced with the masses of part (a)?

Consider the following decomposition reaction in which \(47.20 \mathrm{~g}\) of some compound is decomposed into its elements.

When \(490.0 \mathrm{mg}\) of iron reacts with excess bromine, a mixture of \(\mathrm{FeBr}_{2}\) and \(\mathrm{FeBr}_{3}\) is produced. It is determined that \(35.5 \%\) of the mixture is iron(II) (bromide). What is the total mass of \(\mathrm{FeBr}_{2} / \mathrm{FeBr}_{3}\) mixture produced?