Chapter 3

Some catalytic converters in automobiles contain the manganese oxides \(\mathrm{Mn}_{2} \mathrm{O}_{3}\) and \(\mathrm{MnO}_{2}\)a. Give the names of \(\mathrm{Mn}_{2} \mathrm{O}_{3}\) and \(\mathrm{MnO}_{2}\). b. Calculate the percent manganese by mass in \(\mathrm{Mn}_{2} \mathrm{O}_{3}\) and \(\mathrm{MnO}_{2}\).c. Explain how \(\mathrm{Mn}_{2} \mathrm{O}_{3}\) and \(\mathrm{MnO}_{2}\) are consistent with the law of multiple proportions.

Several chemical reactions have been proposed for the formation of organic compounds from inorganic precursors. Here is one of them:\(\mathrm{H}_{2} \mathrm{S}(g)+\mathrm{FeS}(s)+\mathrm{CO}_{2}(g) \rightarrow \mathrm{FeS}_{2}(s)+\mathrm{HCO}_{2} \mathrm{H}(\ell)\) a. Identify the ions in \(\mathrm{FeS}\) and \(\mathrm{FeS}_{2} .\) Give correct names for each compound. "b. How much HCO \(_{2} \mathrm{H}\) is obtained by reacting \(1.00 \mathrm{g}\) of FeS, \(0.50 \mathrm{g}\) of \(\mathrm{H}_{2} \mathrm{S},\) and \(0.50 \mathrm{g}\) of \(\mathrm{CO}_{2}\) if the reaction results in a \(50.0 \%\) yield?

The formation of organic compounds by the reaction of iron(II) sulfide with carbonic acid is described by the following chemical equation:$$2 \mathrm{FeS}+\mathrm{H}_{2} \mathrm{CO}_{3} \rightarrow 2 \mathrm{FeO}+1 / n\left(\mathrm{CH}_{2} \mathrm{O}\right)_{n}+2 \mathrm{S}$$ a. How much FeO is produced starting with \(1.50 \mathrm{g}\) of FeS and 0.525 mol of \(\mathrm{H}_{2} \mathrm{CO}_{3}\) if the reaction results in a \(78.5 \%\) yield? "b. If the carbon-containing product has a molar mass of \(3.00 \times 10^{2} \mathrm{g} / \mathrm{mol},\) what is the chemical formula of the product?

On the seafloor, iron(II) oxide reacts with water to form \(\mathrm{Fe}_{3} \mathrm{O}_{4}\) and hydrogen in a process called serpentization. a. Balance the following equation for serpentization: \(\mathrm{FeO}(s)+\mathrm{H}_{2} \mathrm{O}(\ell) \rightarrow \mathrm{Fe}_{3} \mathrm{O}_{4}(s)+\mathrm{H}_{2}(g)\). b. When \(\mathrm{CO}_{2}\) is present, the product is methane, not hydrogen. Balance the following chemical equation: \(\mathrm{FeO}(s)+\mathrm{H}_{2} \mathrm{O}(\ell)+\mathrm{CO}_{2}(g) \rightarrow \mathrm{Fe}_{3} \mathrm{O}_{4}(s)+\mathrm{CH}_{4}(g)\).

The solar wind is made up of ions, mostly protons, flowing out from the sun at about \(400 \mathrm{km} / \mathrm{s} .\) Near Earth, each cubic kilometer of interplanetary space contains, on average, \(6 \times 10^{15}\) solar-wind ions. How many moles of ions are in a cubic kilometer of near-Earth space?

A \(100.00 \mathrm{g}\) sample of white powder \(\mathrm{A}\) is heated to \(550^{\circ} \mathrm{C}\) At that temperature the powder decomposes, giving off colorless gas \(\mathrm{B}\), which is denser than air and is neither flammable nor does it support combustion. The products also include \(56 \mathrm{g}\) of a second white powder \(\mathrm{C}\). When gas B is bubbled through a solution of calcium hydroxide, substance A reforms. What are the identities of substances \(A, B,\) and \(C ?\)

You are given a \(0.6240 \mathrm{g}\) sample of a substance with the generic formula MCl \(_{2}\left(\mathrm{H}_{2} \mathrm{O}\right)_{2} .\) After complete drying of the sample (which means removing the 2 mol of \(\mathrm{H}_{2} \mathrm{O}\) per mole of \(\mathrm{MCl}_{2}\) ), the sample has a mass of \(0.5471 \mathrm{g} .\) What is the identity of element M?

A compound found in crude oil consists of \(93.71 \%\) C and \(6.29 \%\) H by mass. The molar mass of the compound is \(128 \mathrm{g} / \mathrm{mol} .\) What is its molecular formula?

A reaction vessel for synthesizing ammonia by reacting nitrogen and hydrogen is charged with \(6.04 \mathrm{kg}\) of \(\mathrm{H}_{2}\) and excess \(\mathrm{N}_{2} .\) A total of \(28.0 \mathrm{kg}\) of \(\mathrm{NH}_{3}\) is produced. What is the percent yield of the reaction?

If a cube of table sugar, which is made of sucrose, \(\mathrm{C}_{12} \mathrm{H}_{22} \mathrm{O}_{11},\) is added to concentrated sulfuric acid, the acid "dehydrates" the sugar, removing the hydrogen and oxygen from it and leaving behind a lump of carbon. What percentage of the initial mass of sugar is carbon?

With respect to the previous question, one way to reduce the formation of acid rain involves trapping the \(\mathrm{SO}_{2}\) by passing smokestack gases through a spray of calcium oxide and \(\mathrm{O}_{2} .\) The product of this reaction is calcium sulfate. a. Write a balanced chemical equation describing this reaction. b. How many metric tons of calcium sulfate would be produced from each ton of \(\mathrm{SO}_{2}\) that is trapped?

The burner in a gas grill mixes 24 volumes of air for every one volume of propane \(\left(\mathrm{C}_{3} \mathrm{H}_{8}\right)\) fuel. Like all gases, the volume that propane occupies is directly proportional to the number of moles of it at a given temperature and pressure. Air is \(21 \%\) (by volume) \(\mathrm{O}_{2} .\) Is the flame produced by the burner fuel-rich (excess propane in the reaction mixture), fuel-lean (not enough propane), or stoichiometric (just right)?

A common mineral in Earth's crust has the chemical composition \(34.55 \%\) Mg, \(19.96 \%\) Si, and \(45.49 \%\) O. What is its empirical formula?

Some indoor air-purification systems work by converting a little of the oxygen in the air to ozone, which oxidizes mold and mildew spores and other biological air pollutants. The chemical equation for the ozone generation reaction is,$$3 \mathrm{O}_{2}(g) \rightarrow 2 \mathrm{O}_{3}(g)$$.It is claimed that one such system generates \(4.0 \mathrm{g}\) of \(\mathrm{O}_{3}\) per hour from dry air passing through the purifier at a flow of \(5.0 \mathrm{L} / \mathrm{min.}\) If 1 liter of indoor air contains \(0.28 \mathrm{g}\) of \(\mathrm{O}_{2}\). a. what fraction of the molecules of \(\mathrm{O}_{2}\) is converted to \(\mathrm{O}_{3}\) by the air purifier? b. what is the percent yield of the ozone generation reaction?

Rebreathing Devices In the first episode of George Lucas's Star Wars series, Qui-Gon Jinn and Obi-Wan Kenobi can visit the underwater world of the Gungans only by using A99 Aquata Breathers, which allow them to survive underwater for up to two hours. While the tiny devices may be from the farfetched world of science fiction, current technology exists for transforming carbon dioxide to oxygen. These self- contained rebreathers are used by a select group of underwater cave explorers and can act as self-rescue devices. The chemistry is based on the following chemical reactions, using either potassium superoxide or sodium peroxide:$$\begin{array}{l}4 \mathrm{KO}_{2}(s)+2 \mathrm{CO}_{2}(g) \rightarrow 2 \mathrm{K}_{2}\mathrm{CO}_{3}(s)+3 \mathrm{O}_{2}(g) \\\2 \mathrm{Na}_{2} \mathrm{O}_{2}(s)+2 \mathrm{CO}_{2}(g) \rightarrow 2 \mathrm{Na}_{2} \mathrm{CO}_{3}(s)+\mathrm{O}_{2}(g)\end{array}$$.a. The respiratory rate at rest for an average, healthy adult is 12 breaths per minute. If the average breath takes in \(0.500 \mathrm{L}\) of \(\mathrm{O}_{2}(d=1.429 \mathrm{g} / \mathrm{L})\) into the lungs, how many grams of \(\mathrm{KO}_{2}\) are needed to produce enough oxygen for two hours underwater? b. Would you need more or less \(\mathrm{Na}_{2} \mathrm{O}_{2}\) to produce an equivalent amount of oxygen? c. Given the densities of \(\mathrm{KO}_{2}(2.14 \mathrm{g} / \mathrm{mL})\) and \(\mathrm{Na}_{2} \mathrm{O}_{2}\) \((2.805 \mathrm{g} / \mathrm{mL}),\) which solid material would occupy less volume in a rebreather device?

Socks containing silver nanoparticles embedded in the fabric are currently marketed as an antidote to smelly socks. Silver is known to have antimicrobial properties, and silver ions are toxic to aquatic life. A study at Arizona State University found that much of the silver particles are lost upon laundering the socks in mild acid.a. Each sock in the study began with \(1360 \mu \mathrm{g}\) of silver. How many moles of silver are contained in each sock?b. As much as \(650 \mu \mathrm{g}\) of silver was lost after four washings. What percent of the silver was lost?