Chapter 9

For the reaction \(\mathrm{Ca}_{3} \mathrm{P}_{2}+\mathrm{H}_{2} \mathrm{O} \rightarrow \mathrm{Ca}(\mathrm{OH})_{2}+\mathrm{PH}_{3}\), (a) Balance the equation. (b) How many grams of \(\mathrm{H}_{2} \mathrm{O}\) would you need to react with \(60.0 \mathrm{~g}\) of \(\mathrm{Ca}_{3} \mathrm{P}_{2} ?\) (c) How many grams of \(\mathrm{PH}_{3}\) could theoretically be produced from the reactant amounts calculated in part (b)?

If you have \(0.262\) mole of iron(III) sulfate, how many oxygen atoms do you have?

Acetaminophen, used in many over-the-counter pain relievers, has a molecular formula of \(\mathrm{C}_{8} \mathrm{H}_{9} \mathrm{NO}_{2} .\) Calculate the mass percentage of each element in acetaminophen.

Consider the unbalanced chemical equation \(\mathrm{KCl}+\mathrm{O}_{2} \rightarrow \mathrm{KClO}_{3}\) If you react \(42.6 \mathrm{~g}\) of \(\mathrm{KCl}\) and \(36.5 \mathrm{~g}\) of \(\mathrm{O}_{2}\) and the reaction has a percent yield of \(56.0 \%\), how many grams of \(\mathrm{KClO}_{3}\) are produced?

Sucrose has the molecular formula \(\mathrm{C}_{12} \mathrm{H}_{22} \mathrm{O}_{11} .\) If you were to completely burn \(2.00 \mathrm{~g}\) of sucrose in a stream of oxygen, how many grams of \(\mathrm{CO}_{2}\) and \(\mathrm{H}_{2} \mathrm{O}\) would be produced?

If you have \(44.6 \mathrm{~g}\) of carbon tetrachloride, how many atoms of chlorine do you have?

For the reaction \(\mathrm{BF}_{3}+\mathrm{H}_{2} \mathrm{O} \rightarrow \mathrm{H}_{3} \mathrm{BO}_{3}+\mathrm{HBF}_{4}\) (a) Balance the equation. (b) If you react \(24.2 \mathrm{~g}\) of \(\mathrm{BF}_{3}\) with an excess of water and generate \(14.8 \mathrm{~g}\) of \(\mathrm{HBF}_{4}\), what is your percent yield?

The ingredients for making 1 dozen cupcakes are: 5 tablespoons butter 1 cup sugar 2 eggs 2 cups flour 1 cup milk If you have only 5 eggs but plenty of all of the other ingredients: (a) How many cupcakes can you make? (b) How many cups of sugar do you need to make the number of cupcakes calculated in (a)?

Chrome yellow, a pigment used in paints, is \(64.11 \%\) by mass \(\mathrm{Pb}, 16.09 \%\) by mass \(\mathrm{Cr}\), and \(19.80 \%\) by mass O. What is the empirical formula of this compound?

Silicon nitride, \(\mathrm{Si}_{3} \mathrm{~N}_{4}\), is a ceramic material capable of withstanding high temperatures. It can be produced using the following unbalanced reaction: \(\mathrm{SiCl}_{4}+\mathrm{NH}_{3} \rightarrow \mathrm{Si}_{3} \mathrm{~N}_{4}+\mathrm{HCl}\) If \(64.2 \mathrm{~g}\) of \(\mathrm{SiCl}_{4}\) is reacted with \(20.0 \mathrm{~g}\) of \(\mathrm{NH}_{3}\), how many grams of \(\mathrm{Si}_{3} \mathrm{~N}_{4}\) are produced if the reaction has a \(96.0 \%\) yield?

Vitamin \(\mathrm{C}\), also known as ascorbic acid, contains carbon, hydrogen, and possibly oxygen. A \(0.160 \mathrm{~g}\) sample of ascorbic acid is subjected to combustion analysis, yielding \(40.93 \%\) C and \(4.58 \%\) H. If the molar mass of ascorbic acid is approximately \(176 \mathrm{~g} / \mathrm{mol}\), what is its molecular formula?

Determine the mass percent of each element in magnesium phosphate.

For the reaction \(\mathrm{SiCl}_{4}+\mathrm{H}_{2} \mathrm{O} \rightarrow \mathrm{SiO}_{2}+\mathrm{HCl}\), (a) Balance the equation. (b) If you want to make \(120.0 \mathrm{~g}\) of \(\mathrm{HCl}\), how many grams of \(\mathrm{SiCl}_{4}\) and \(\mathrm{H}_{2} \mathrm{O}\) do you need? (c) How many grams of \(\mathrm{SiO}_{2}\) are produced from the quantities calculated in (b)?

A compound is \(91.77 \%\) by mass \(\mathrm{Si}\) and \(8.23 \%\) by mass \(\mathrm{H}\) and has a molar mass of approximately \(122 \mathrm{~g} / \mathrm{mol}\). What is its molecular formula?

Iron(III) oxide reacts with carbon monoxide to give iron metal and carbon dioxide. If you begin the reaction with \(24.0 \mathrm{~g}\) of iron(III) oxide and \(34.0 \mathrm{~g}\) of carbon monoxide, what is the theoretical yield in grams of carbon dioxide?

The compound ibuprofen, used in some pain relievers, has the molecular formula \(\mathrm{C}_{13} \mathrm{H}_{18} \mathrm{O}_{2}\). If \(0.250 \mathrm{~g}\) of ibuprofen is burned in oxygen, how many grams of \(\mathrm{CO}_{2}\) and \(\mathrm{H}_{2} \mathrm{O}\) will be produced?

If you have \(200.0 \mathrm{~g}\) of dinitrogen pentoxide, how many atoms of nitrogen do you have? How many atoms of oxygen do you have?

Potassium nitrate decomposes upon heating to form potassium oxide, nitrogen gas, and oxygen gas. If \(19.6 \mathrm{~g}\) of potassium nitrate have decomposed, how many molecules of oxygen gas have been formed?

Tetraphosphorus decoxide, \(\mathrm{P}_{4} \mathrm{O}_{10}\), reacts with water to form phosphoric acid. If \(52.5 \mathrm{~g}\) of \(\mathrm{P}_{4} \mathrm{O}_{10}\) reacted with \(25.0 \mathrm{~g}\) of water, how many grams of \(\mathrm{H}_{3} \mathrm{PO}_{4}\) could theoretically be produced?

Determine the mass percent of each element in aluminum sulfate.

Consider the unbalanced chemical equation \(\mathrm{Cl}_{2} \mathrm{O}_{7}+\mathrm{H}_{2} \mathrm{O} \rightarrow \mathrm{HClO}_{4}\) The reaction is carried out at \(82.0 \%\) yield and gives \(52.8 \mathrm{~g}\) of \(\mathrm{HClO}_{4}\) (a) What is the theoretical yield of \(\mathrm{HClO}_{4}\) ? (b) How many grams of \(\mathrm{Cl}_{2} \mathrm{O}_{7}\) and \(\mathrm{H}_{2} \mathrm{O}\) were consumed in the reaction?

The compound naphthalene, which is used in mothballs, contains carbon, hydrogen, and possibly oxygen. When \(0.220 \mathrm{~g}\) of naphthalene is subjected to combustion analysis, it yields \(93.66 \% \mathrm{C}\) and \(6.31 \% \mathrm{H}\). If the molar mass of naphthalene is approximately \(128 \mathrm{~g} / \mathrm{mol}\), what is its molecular formula?

Ethylene gas \(\left(\mathrm{C}_{2} \mathrm{H}_{4}\right)\) reacts with fluorine gas \(\left(\mathrm{F}_{2}\right)\) to form carbon tetrafluoride gas and hydrogen fluoride gas. If \(2.78 \mathrm{~g}\) of ethylene reacted with an excess of fluorine, how many grams of each product could theoretically be produced?

How many grams of sulfur hexafluoride would you need to have \(5.25 \times 10^{24}\) fluorine atoms?

Consider the unbalanced chemical equation \(\mathrm{HSbCl}_{4}+\mathrm{H}_{2} \mathrm{~S} \rightarrow \mathrm{Sb}_{2} \mathrm{~S}_{3}+\mathrm{HCl}\) If \(118.2 \mathrm{~g}\) of \(\mathrm{HSbCl}_{4}\) reacts with \(47.9 \mathrm{~g}\) of \(\mathrm{H}_{2} \mathrm{~S}\) and produces \(41.6 \mathrm{~g}\) of \(\mathrm{HCl}\), what is the percent yield for the reaction?

Caffeine is made up of \(49.48 \%\) by mass \(C, 5.19 \%\) by mass \(\mathrm{H}, 28.85 \%\) by mass \(\mathrm{N}\), and \(16.48 \%\) by mass \(\mathrm{O}\). If its molar mass is approximately \(194 \mathrm{~g} / \mathrm{mol}\), what is the molecular formula of caffeine?

For the reaction \(\mathrm{NH}_{3}+\mathrm{NO} \rightarrow \mathrm{N}_{2}+\mathrm{H}_{2} \mathrm{O}:\) (a) Balance the equation. (b) If you react \(15.0 \mathrm{~g} \mathrm{NH}_{3}\) with \(22.0 \mathrm{~g} \mathrm{NO}\) and you produce \(13.3 \mathrm{~g} \mathrm{~N}_{2}\), what is your percent yield?

Nicotine has the formula \(\mathrm{C}_{10} \mathrm{H}_{14} \mathrm{~N}_{2}\). Determine the mass percent of each element.

Consider the unbalanced chemical equation \(\mathrm{CaC}_{2}+\mathrm{CO} \rightarrow \mathrm{C}+\mathrm{CaCO}_{3}\) When the reaction is complete, \(135.4 \mathrm{~g}\) of \(\mathrm{CaCO}_{3}\) produced and \(38.5 \mathrm{~g}\) of \(\mathrm{CaC}_{2}\) is left over. Assuming the reaction had a \(100 \%\) yield, what were the mass of the two reactants at the beginning of the reaction

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?

The compound \(3^{\prime}\) -azido- \(3^{\prime}\) -thymidine (AZT) is used in the treatment of AIDS. The molecular formula of \(\mathrm{AZT}\) is \(\mathrm{C}_{10} \mathrm{H}_{13} \mathrm{~N}_{5} \mathrm{O}_{4}\). What is the mass percent of each element in AZT?

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.

Consider the unbalanced chemical equation \(\mathrm{N}_{2} \mathrm{O}_{4}+\mathrm{N}_{2} \mathrm{H}_{4} \rightarrow \mathrm{N}_{2}+\mathrm{H}_{2} \mathrm{O}\) (a) Balance the equation. (b) If \(42.32 \mathrm{~g}\) of \(\mathrm{N}_{2}\) was produced and the reaction yield was \(67.5 \%\), how many grams of \(\mathrm{N}_{2} \mathrm{O}_{4}\) and \(\mathrm{N}_{2} \mathrm{H}_{4}\) were consumed in the reaction?

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?

Lead(II) sulfide reacts with hydrogen peroxide to give lead(II) sulfate as shown in the unbalanced chemical equation \(\mathrm{PbS}+\mathrm{H}_{2} \mathrm{O}_{2} \rightarrow \mathrm{PbSO}_{4}+\mathrm{H}_{2} \mathrm{O}\) If \(63.2 \mathrm{~g}\) of \(\mathrm{PbS}\) is reacted with \(48.0 \mathrm{~g}\) of \(\mathrm{H}_{2} \mathrm{O}_{2}\) (a) Which is the limiting reagent? (b) How many grams of excess reactant remain after the reaction is complete?

The hormone estradiol contains carbon, hydrogen, and oxygen and has a molar mass of approximately \(272 \mathrm{~g} / \mathrm{mol}\). When \(1.15 \mathrm{~g}\) of estradiol is subjected to combustion analysis, the results yield \(79.26 \% \mathrm{C}\) and \(8.88 \% \mathrm{H}\). What is its molecular formula?

Consider the unbalanced chemical equation \(\mathrm{CaCN}_{2}+\mathrm{H}_{2} \mathrm{O} \rightarrow \mathrm{CaCO}_{3}+\mathrm{NH}_{3}\) If you began the reaction with \(5.65 \mathrm{~g}\) of \(\mathrm{CaCN}_{2}\) and \(12.2 \mathrm{~g}\) of \(\mathrm{H}_{2} \mathrm{O}\), how many grams of \(\mathrm{NH}_{3}\) would be produced if the reaction had an \(86.0 \%\) yield?

Saccharin, which is used as an artificial sweetener, is made up of \(45.90 \%\) by mass \(C, 2.75 \%\) by mass \(\mathrm{H}, 26.20 \%\) by mass \(\mathrm{O}, 7.65 \%\) by mass \(\mathrm{N}\), and \(17.50 \%\) by mass \(\mathrm{S}\). If the molar mass of saccharin is \(183.19 \mathrm{~g} / \mathrm{mol}\), what is its molecular formula?

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?

The amino acid arginine is made up of \(41.37 \%\) by mass \(\mathrm{C}, 8.10 \%\) by mass \(\mathrm{H}, 32.16 \%\) by mass \(\mathrm{N}\), and \(18.37 \%\) by mass \(\mathrm{O}\). If the molar mass of arginine is approximately \(174 \mathrm{~g} / \mathrm{mol}\), what is its molecular formula?

Consider the unbalanced chemical equation \(\mathrm{As}_{4} \mathrm{~S}_{6}+\mathrm{O}_{2} \rightarrow \mathrm{As}_{4} \mathrm{O}_{6}+\mathrm{SO}_{2}\) (a) How many grams of \(\mathrm{O}_{2}\) are needed to react completely with \(58.9 \mathrm{~g}\) of \(\mathrm{As}_{4} \mathrm{~S}_{6}\) ? (b) If \(41.2 \mathrm{~g}\) of \(\mathrm{SO}_{2}\) is produced, what is the percent yield for the reaction?

Consider the balanced chemical equation \(2 \mathrm{~A}+\mathrm{B} \rightarrow 2 \mathrm{C}+\mathrm{D}\) When \(8.0 \mathrm{~g}\) of A reacts completely with \(6.0 \mathrm{~g}\) of \(\mathrm{B}\), \(10.0 \mathrm{~g}\) of \(\mathrm{C}\) and \(4.0 \mathrm{~g}\) of \(\mathrm{D}\) are produced. Assuming the yield is \(100 \%\), (a) Which has a greater molar mass, A or C? (b) Which has a greater molar mass, A or B? (c) Which has a greater molar mass, A or D? (d) If the molar mass of \(\mathrm{A}\) is \(24.0 \mathrm{~g} / \mathrm{mol}\), determine the molar mass of \(\mathrm{B}, \mathrm{C}\), and \(\mathrm{D}\).

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?

The flavoring agent vanillin contains carbon, hydrogen, and possibly oxygen. When \(0.450 \mathrm{~g}\) of vanillin is subjected to combustion analysis, the results are \(63.08 \% \mathrm{C}\) and \(5.30 \% \mathrm{H}\). If the molar mass is approximately \(152 \mathrm{~g} / \mathrm{mol}\), what is the molecular formula of vanillin?

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 unbalanced chemical equation \(\mathrm{Cr}+\mathrm{S}_{8} \rightarrow \mathrm{Cr}_{2} \mathrm{~S}_{3}\) If we need to produce \(235.0 \mathrm{~g}\) of \(\mathrm{Cr}_{2} \mathrm{~S}_{3}\) and the reaction has a \(63.80 \%\) yield, how many grams of each reactant do we need?

Consider the unbalanced chemical equation \(\mathrm{Al}_{2} \mathrm{~S}_{3}+\mathrm{H}_{2} \mathrm{O} \rightarrow \mathrm{Al}(\mathrm{OH})_{3}+\mathrm{H}_{2} \mathrm{~S}\) If \(56.0 \mathrm{~g}\) of aluminum sulfide reacts with \(48.2 \mathrm{~g}\) of water, (a) Which is the excess reactant? (b) What mass in grams of the excess reactant remains after the reaction is complete?

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