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Course Number: CHEM 2301, Spring 2010

College/University: South Texas College

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Exercises c. C12H22011(S) + 02(g) CO2(g) d. Fe(s) + 02(g) Fe203(S) 123 e. FeO(s) -* + 02(g) -* F~03(S) -* + H20(g) 96. Balance the following equations: a. Cr(s) + Ss(s) Cr2S3(S) -* b. NaHC03(s) ~ Na2C03(S) + CO2 (g) + HP(g) In this equation, the 8H20 in Ba(OH)z . 8H20 indicates the presence of eight water molecules. This compound is called barium hydroxide octahydrate. a. Balance the equation. b. What...

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C12H22011(S) Exercises c. + 02(g) CO2(g) d. Fe(s) + 02(g) Fe203(S) 123 e. FeO(s) -* + 02(g) -* F~03(S) -* + H20(g) 96. Balance the following equations: a. Cr(s) + Ss(s) Cr2S3(S) -* b. NaHC03(s) ~ Na2C03(S) + CO2 (g) + HP(g) In this equation, the 8H20 in Ba(OH)z . 8H20 indicates the presence of eight water molecules. This compound is called barium hydroxide octahydrate. a. Balance the equation. b. What mass of ammonium thiocyanate (NH4SCN) must be used if it is to react completely with 6.5 g barium hydroxide octahydrate? 103. Elixirs such as Alka-Seltzer use the reaction of sodium bicarbonate with citric acid in aqueous solution to produce a fizz: c. KCI03(s) Heat) KCI(s) + 02(g) d. Eu(s) + HF(g) EuF3(s) + Hig) -* 97. Silicon is produced for the chemical and electronics industries by the following reactions. Give the balanced equation for each reaction. a. Si02(s) 3NaHC03(aq) + C6HsOiaq) ~ 3C02(g) + 3H20(l) + Na3C6Hs07(aq) + C(s) a:ll~~::~:/ Si(s) -* Si(s) + CO(g) b. Silicon tetrachloride is reacted with very pure magnesium, producing silicon and magnesium chloride. a. What mass of C6Hs07 should be used for every 1.0 X 102 mg NaHC03? b. What mass of CO2(g) could be produced from such a mixture? 104. Phosphorus can be prepared from calcium phosphate by the following reaction: c. Na2SiF6(s) + Na(s) + NaF(s) 98. Glass is a mixture of several compounds, but a major constituent of most glass is calcium silicate, CaSi03. Glass can be etched by treatment with hydrofluoric acid; HF attacks the calcium silicate of the glass, producing gaseous and water-soluble products (which can be removed by washing the glass). For example, the volumetric glassware in chemistry laboratories is often graduated by using this process. Balance the following equation for the reaction of hydrofluoric acid with calcium silicate. 2Ca3(P04Ms) + 6Si02(s) + IOC(s) ~ 6CaSi03(s) + P4(s) + IOCO(g) Phosphorite is a mineral that contains Ca3(P04)2 phosphorus-containing compounds. What is amount of P4 that can be produced from 1.0 kg if the phorphorite sample is 75% Ca3(P04)2 by an excess of the other reactants. Coke 105. is an impure dustrial production coke is 95% carbon to react completely plus other nonthe maximum of phosphorite mass? Assume Reaction Stoichiometry 99. Over the years, the thermite reaction has been used for welding railroad rails, in incendiary bombs, and to ignite solid-fuel rocket motors. The reaction is form of carbon that is often used in the inof metals from their oxides. If a sample of by mass, determine the mass of coke needed with 1.0 ton of copper(II) oxide. 2CuO(s) + C(s) ~ 2Cu(s) + CO2(g) What masses of iron(Ill) oxide and aluminum must be used to produce 15.0 g iron? What is the maximum mass of aluminum oxide that could be produced? 100. The reaction between potassium chlorate and red phosphorus takes place when you strike a match on a matchbox. If you were to react 52.9 g of potassium chlorate (KCI03) with excess red phosphorus, what mass of tetraphosphorus decaoxide (P40IO) would be produced? 106. The space shuttle environmental control system handles excess CO2 (which the astronauts breathe out; it is 4.0% by mass of exhaled air) by reacting it with lithium hydroxide, LiOH, pellets to form lithium carbonate, Li2C03, and water. If there are 7 astronauts on board the shuttle, and each exhales 20. L of air per minute, how long could clean air be generated if there were 25,000 g of LiOH pellets available for each shuttle mission? Assume the density of air is 0.0010 g1mL. Limiting Reactants and Percent Yield 107. Consider the reaction between below. O(g) and 02(g) represented 101. The reusable booster rockets of the U.S. space shuttle employ a mixture of aluminum and ammonium perchlorate for fuel. A possible equation for this reaction is 3AI(s) + 3NH4CI04(s) ~ A120ls) What mass of NH4Cl04 every kilogram of AI? + AICI3(s) + 3NO(g) + 6H20(g) should be used in the fuel mixture for What is the balanced equation for this reaction and what is the limiting reactant? 108. Consider the following reaction: 102. One of relatively few reactions that takes place directly between two solids at room temperature is Ba(OH)2 . 8H20(s) + NH4SCN(s) ~ Ba(SCNMs) + H20(l) + NH3(g)

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South Texas College - CHEM - 2301
---.-124Chapter ThreeStoichiometry116. Consider the following unbalanced reaction: P4(s)If a container were to have 10 molecules of O2 and 10 molecules of NH3 initially, how many total molecules (reactants plus products) would be present in the co
South Texas College - CHEM - 2301
AdditionalExercises125is an intermediate step in the conversion of the nitrogen in organic compounds into nitrate ions. What mass of bacterial tissue is produced in a treatment plant for every 1.0 X 104 kg of wastewater containing 3.0% NH4 + ions by ma
South Texas College - CHEM - 2301
126Chapter ThreeStoichiometry141. A sample of LSD (n-Iysergic acid diethylamide, C24H3oN30) is added to some table salt (sodium chloride) to form a mixture. Given that a 1.00-g sample of the mixture undergoes combustion to produce 1.20 g of CO2, what i
South Texas College - CHEM - 2301
MarathonProblems127excess oxygen, 1.21 g of water is formed. Determine the formula of the compound. Assume water is the only product that contains hydrogen. 158. A 2.25-g sample of scandium metal is reacted with excess hydrochloric acid to produce 0.15
South Texas College - CHEM - 2301
128Chapter ThreeStoichiometrymass spectrum of substance C shows a parent molecular ion with a mass-to-charge ratio of 26. d. Substance D is the hydroxide of the metal in substance A. 172. Consider the following balanced chemical equation: A + 5B -+ 3C
South Texas College - CHEM - 2301
3.1. ~ Counting 3.3 ~ The Moleby Weighing3.2 ~ Atomic Masses 3.4 ~ Molar Mass 3.5 ~ Learning to Solve Problems 3.6 ~ Percent Composition ofCompounds3. 7 ~ Determiningthe Formula of a Compound Chemical Reactions3.8 ~ Chemical EquationsThe Meaning of
South Texas College - CHEM - 2301
Whether you're using OWLor WebAssign, you've got online tools designed to meet your learning style (see your professor to find out if either program is available with your textbook). To learn more go to www.cengage.com/owl or www.webassign.net/brookscole.
South Texas College - CHEM - 2301
78ChapterThreeStoichiometryCan we count these nonidentical beans by weighing? Yes. The key piece of information we need is the average mass of the jelly beans. Let's compute the average mass for our 10-bean sample. Average mass= -total mass of beans
South Texas College - CHEM - 2301
3.2AtomicMasses79atoms or molecules are passed into a beam of high-speed electrons, which knock electrons off the atoms or molecules being analyzed and change them into positive ions. An applied electric field then accelerates these ions into a magnet
South Texas College - CHEM - 2301
80Chapter ThreeStoichiometry. B"0100cos "oilI~!:!" :j"B4-<E91'" 0E ;:l80 60 40 20 0 20 21 9.; c: .!lC.Dilc:.sE,II.Dc: 0 .'" "18II20II21I'II;> .p4~II~24(c)" '".~ I22Mass number192223Mass number(a)(b)
South Texas College - CHEM - 2301
3.3The MoLe813.3 ~ The MoleBecause samples of matter typically contain so many atoms, a unit of measure called the mole has been established for use in counting atoms. For our purposes, it is most convenient to define the mole (abbreviated mol) as the
South Texas College - CHEM - 2301
82ChapterThreeStoichiometryTable 3.1.ElementComparison of 1.-MoleSamples of Various ElementsNumber of Atoms Present Mass of Sample (g)AluminumCopper IronSulfurIodine Mercury6.022 X 1023 6.022 X 1023 6.022 X 1023 6.022 X 1023 6.022 X 1023 6.022
South Texas College - CHEM - 2301
3.3The Mole83EXAMPLE3.3Aluminum (AI) is a metal with a high strength-to-mass ratio and a high resistance to corrosion; thus it is often used for structural purposes. Compute both the number of moles of atoms and the number of atoms in a 1O.0-g sample
South Texas College - CHEM - 2301
84Chapter ThreeStoichiometry Reality Check: Note that 5.68 mg of silicon is clearly much less than 1 mol of silicon (which has a mass of 28.09 g), so the final answer of 1.22 X 1020 atoms (compared with 6.022 X 1023 atoms) is in the right direction.SEE
South Texas College - CHEM - 2301
3.4Molar Mass85molecules, we need a special name for the fundamental unit of these materials. Instead of molecule, we use the term formula unit. Thus CaC03 is the formula unit for calcium carbonate, and NaCl is the formula unit for sodium chloride.EXA
South Texas College - CHEM - 2301
86Chapter ThreeStoichiometry Thus the mass of 1 mole of CaC03 (1 mol Ca2+ plus 1 mol CO/-) is 100.09 g. This is the molar mass. b. The mass of 1 mole of CaC03 is 100.09 g. The sample contains nearly 5 moles, or close to 500 g. The exact amount is determ
South Texas College - CHEM - 2301
3.5Learningto Solve Problems87To determine the number of carbon atoms present, we must multiply the number of molecules by 7, since each molecule of isopentyl acetate contains seven carbon atoms: 5 X 1015 IllQleeuteS X To show the correct number of si
South Texas College - CHEM - 2301
88Chapter ThreeStoichiometrysuppose you know how to get from your house to the store (and back) and from your house to the library (and back). Can you get from the library to the store without having to go back home? Probably not if you have only memor
South Texas College - CHEM - 2301
3.6PercentCompositionof Compounds89For example, for ethanol, which has the formula C2HsOH, the mass of each element present and the molar mass are obtained as follows: Mass of C Mass of H Mass of 0=2 mot 6 motX12.01 mot g 1.008 motg=24.02 g 6.
South Texas College - CHEM - 2301
90Chapter ThreeStoichiometryHow do we get there? What is the mass of each element in 1 mol C1oH140? Mass of C in 1 mol = 10 mot Mass ofH in 1 mol Mass of 0 in 1 mol What is the molar mass of ClOH140? 120.1 g ClOCarvone = X12.01!r 1.008!r l6.00!r=12
South Texas College - CHEM - 2301
3.7Determiningthe Formulaof a Compound93n, the atomsPROBLEM-SOLVINGSTRATEGYEmpirical Formula Determination Since mass percentage gives the number of grams of a particular element per 100 grams of compound, base the calculation on 100 grams of com
South Texas College - CHEM - 2301
94ChapterThreeStoichiometryWhat information do we need to find the empirical formula? ./ Mass of each element in 100.00 g of compound ./ Moles of each element How do we get there? What is the mass of each element in 100.00 g of compound? CI 71.65 g C
South Texas College - CHEM - 2301
3.7Determiningthe Formulaof a Compound95What information do we need to find the empirical formula? ./ Mass of each element in 100.00 g of compound ./ Moles of each element How do we get there? What is the mass of each element in 100.00 g of compound?
South Texas College - CHEM - 2301
96Chapter ThreeStoichiometryNow we can compute moles .of atoms present per mole of compound: Chlorine: Carbon: Hydrogen: 70.90 g-et mol compound 24.02g-C mol compound 4.03 g-H mol compoundX X1 mol Cl 2.000 mol Cl 35.45 g-et mol compound 1 mol C 12.01
South Texas College - CHEM - 2301
3.8ChemicalEquations97What are the moles of each element in 1 mol caffeine? 96.09 g-e Carbon: Hydrogen: Nitrogen: Oxygen: mol caffeine 1O.0g-H mol caffeine 56.07 g-N mol caffeine 32.02 g-cfw_) mol caffeineX X1 mol C 12.01 g-e 1 molH 1.008 g-H 1 mol
South Texas College - CHEM - 2301
98Chapter ThreeStoichiometryNotice that now we have the same number of each type of atom represented among the reactants and the products. We can represent the preceding situation in a shorthand manner by the following chemical equation: CH4+ 202~CO
South Texas College - CHEM - 2301
3.9BalancingChemicalEquations99Table 3.2Information Conveyed by the Balanced Equation for the Combustion of MethaneReactants ProductsCH4(g) 1 molecule 1 mole+ 202(g)+2 molecules~ ~ ~ ~CO2(g) 1 molecule 1 mole+ 2 moles+ + +2H20(g) 2 molecul
South Texas College - CHEM - 2301
Gases5.1 ~ PressureUnits of Pressure5.2 ~ The Gas Laws of Boyle,Charles, Charles's Avogadro's and Avogadro Law Law Boyle's Law5.3 ~ The Ideal Gas Law 5.4 ~ Gas StoichiometryMolar Mass of a Gas5.5 ~ Dalton's Law of PartialPressures Collecting a Gas
South Texas College - CHEM - 2301
atter exist in th,ce distinct physical states: gas, liquid, and solid. Although relatively few substances exist in the gaseous state under typical conditions, gases are very important. For example, we live immersed in a gaseous solution. The earth's atmos
South Texas College - CHEM - 2301
182ChapterFiveGasesFigure 5.l.The pressure exerted by the gases in the atmosphere can be demonstrated by boiling water in a large metal can (a) and then turning off the heat and sealing the can. As the can cools, the water vapor condenses, lowering t
South Texas College - CHEM - 2301
5.2The Gas Laws of Boule, Charles, and Avogadro183Figure 5.3A simple manometer, a device for measuring the pressure of a gas in a container. The pressure of the gas is given by h (the difference in mercury levels) in units of torr (equivalent to mm Hg
South Texas College - CHEM - 2301
184ChapterFiveGasesMercury addedTable 5.l.Volume (in3)Actual Data from Boyle's ExperimentPressure (in Hg) Pressure x Volume (in Hg x in3)-1Gas~If JlIGashjII117.5 87.2 70.7 58.8 44.2 35.3 29.112.0 16.0 20.0 24.0 32.0 40.0 48.014.1 14.0 1
South Texas College - CHEM - 2301
5.2The Gas Laws of Boyle, Charles, and Avogadro185Ideal 22.45 22.40 ~-Figure 5.6A plot of PV versus P for several gases at pressures below 1 atm. An ideal gas is expected to have a constant value of PV, as shown by the dotted line. Carbon dioxide sho
South Texas College - CHEM - 2301
186ChapterFiveGasesThe fact that the volume decreases in Example 5.2 makes sense because the pressure was increased. To help eliminate errors, make it a habit to check whether an answer to a problem makes physical (common!) sense. We mentioned before
South Texas College - CHEM - 2301
5.2The Gas Laws of Boyle, Charles,and Avogadro187He 6 5 4 ~3;:.He 6 CH454-:2 H2~HPN02.~3;:.<~-;:;:2".:-.-~Figure 5.9Plots of V versus T as in Fig. 5.8, except here the Kelvin scale is used for temperature.-300r-:;~=IOO 0 100 200 3
South Texas College - CHEM - 2301
188Chapter FiveGasesHow do we get there?N2 H2What is Charles's law (in aform useful with our knowns)? Vi=V2r.What is V2? V2T2=2.79 L1Ar CH4=(T2)i TVi=(311 K) 288 K 2.58 LReality Check: The new volume is greater than the original volume
South Texas College - CHEM - 2301
5.3The IdeaL Gas Law189What is the mole ratio between 03 and 02? 2 mol 03 3 mol O2 Now we can calculate the moles of 03 formed. 0.50 mel-<'J2X2 mol 033 mel-<'J2=0.33 mol 03What is the volume of 03 produced? Avogadro's law states that V = an, whic
South Texas College - CHEM - 2301
190ChapterFiveGasesThe ideal gas law applies best at pressures smaller than 1 atm.The ideal gas law is an equation of state for a gas, where the state of the gas is its condition at a given time. A particular state of a gas is described by its pressu
South Texas College - CHEM - 2301
5.3The Ideal Gas Law191The basic assumption we make when using the ideal gas law to describe a change in state for a gas is that the equation applies equally well to both the initial and final states. In dealing with changes in state, we always place t
South Texas College - CHEM - 2301
192Chapter FiveGasesEXAMPLE5.8A sample of methane gas that has a volume of 3.8 L at 5C is heated to 86C at constant pressure. Calculate its new volume.SolutionWhere are we going? To use the ideal gas equation to determine the final volume What do w
South Texas College - CHEM - 2301
5.3The Ideal Gas Law193EXAMPLE5.9A sample of diborane gas (B2H6), a substance that bursts into flame when exposed to air, has a pressure of 345 torr at a temperature of -15C and a volume of 3.48 L. If conditions are changed so that the temperature is
South Texas College - CHEM - 2301
194Chapter FiveGasesEXAMPLE5.10-:=A sample containing 0.35 mol argon gas at a temperature of 13C and a pressure of 568 torr is heated to 56C and a pressure of 897 torr. Calculate the change in volume that occurs.SolutionWhere are we going? To use
South Texas College - CHEM - 2301
5.4Gas Stoichiometry195Table 5.2Molar Volumes for Various Gases at oC and 1 atmMolar Volume (L) 22.397 22.402 22.433 22.434 22.397 22.260 22.079GasOxygen (02) itrogen (N2) Hydrogen (H2) Helium (He) Argon (Ar) Carbon dioxide (C02) Ammonia (NH3)5.11
South Texas College - CHEM - 2301
196Chapter FiveGasesSolutionWhere are we going? To use stoichiometry to determine the volume of CO2 produced What do we know? ./ CaC03(s) What information do we need? ./ Molar volume of a gas at STP is 22.42 L How do we get there? We need to use the s
South Texas College - CHEM - 2301
5.4Gas Stoichiometry197SolutionWhere are we going? To determine the volume of CO2 produced What do we know?CH4O21.25 atm 35.0 L 31C + 273 = 304 KCO2 2.50 atm ? 125C + 273 = 398 KpV T1.65 atm 2.80 L 25C + 273 = 298 KWhat information do we need?
South Texas College - CHEM - 2301
198ChapterFiveGasesIn this case n = 0.189 mol, T = 125C R = 0.08206 L . atmlK . mol. Thus V=+ 273 = 398 K, P2.50 atm, ane(0.189 mot)(0.08206 L . atrrfIK . mot)(398 K)=2.50 atm2.47 LThis represents the volume of CO2 produced under these conditi
South Texas College - CHEM - 2301
5.5Dalton's Law of Partial Pressures199How do we get there? Molar mass = dRT =P(1.95~)(01:;'08206 1:; atrr1) R . mol (300. R) 1.50 aan=32.0 g/molReality Check: These are the units expected for molar mass.SEE EXERCISES 5.75 THROUGH 5.78You cou
South Texas College - CHEM - 2301
200Chapter FiveGasesThis important observation indicates some fundamental characteristics of an ideal gas. The fact that the pressure exerted by an ideal gas is not affected by the identity (composition) of the gas particles reveals two things about id
South Texas College - CHEM - 2301
5.5Dalton'sLaw of PartialPressures201Separating GasesAssume you work for an oil company that owns a huge natural gas reservoir containing a mixture of methane and nitrogen gases. In fact, the gas mixture contains so much nitrogen that it is unusable
South Texas College - CHEM - 2301
202ChapterFiveGasesThe Chemistry of Air BagsMost experts agree that air bags represent a very important advance in automobile safety. These bags, which are stored in the auto's steering wheel or dash, are designed to inflate rapidly (within about 40
South Texas College - CHEM - 2301
lr-,Lu5.5Dalton's Law of Partial Pressures203What do we know? ./ Po,./ PTOTAL= =156 torr 743 torrHow do we get there? The mole fraction of O2 can be calculated from the equation Xo, -= -Po,PTOTAL=156 torr 743 terr= 0.210Note that the mo
South Texas College - CHEM - 2301
204Chapter FiveGasesOxygen plus water vapor'-,Figure 5.13The production of oxygen by thermal decomposition of KCI03. The Mn02 is mixed with the KCI03 to make the reaction faster.EXAMPLE5.18A sample of solid potassium chlorate (KCI03) was heated i
South Texas College - CHEM - 2301
5.6The Kinetic Molecular Theory of Gases205In this case, the partial pressure of the O2 isP 0, = 733 torr = 760 terr/atm733 terf=0.964 atmTo find the moles of O2 produced, we usev=R nO20.650 LT = 22C=+ 273 =295 K0.08206 L . atmlK . mol(0
South Texas College - CHEM - 2301
206ChapterFiveGases"'~ s.ri~(a)(b)Figure 5.14(a) One mole of N2(~ has a volume of approximately 35 mL and a density of 0.81 g/mL. (b) One mole of N2(g) has a volume of 22.42 L (STP) and a density of 1.2 x 10-3 g/mL. Thus the ratio of the volumes o
South Texas College - CHEM - 2301
5.6The KineticMolecularTheory of Gases207Volume is decreasedFigure 5.15The effects of decreasing the volume of a sample of gas at constant temperature.Pressure and Volume (Boyle's Law)We have seen that for a given sample of gas at a given tempera
South Texas College - CHEM - 2301
208ChapterFiveGases:2Temperature is increasedFigure 5.1.7The effects of increasing the temperature of a sample of gas at constant pressure.This can be visualized from the KMT, as shown in Fig. 5.17. When the gas is heated to a higher temperature,
South Texas College - CHEM - 2301
5.6The KineticMolecularTheoryof Gases209Deriving the Ideal Gas LawWe have shown qualitatively that the assumptions of the KMT successfully account for the observed behavior of an ideal gas. We can go further. By applying the principles of physics t
South Texas College - CHEM - 2301
210ChapterFiveGaseswith the result from the kinetic molecular theory, PV ex: T nFrom theoryThese expressions have exactly the same form if R, the universal gas constant, is considered the proportionality constant in the second case. The agreement be
South Texas College - CHEM - 2301
5.6The KineticMolecularTheoryof Gases211RR==0.08206 L . atm K mol J 8.3145- -K 1 . moBefore we can use this equation, we need to consider the units for R. So far we have used 0.08206 L . atm/K . mol as the value of R. But to obtain the desired
South Texas College - CHEM - 2301
212ChapterFiveGasesFigure 5.l.9Path of one particle in a gas. Any given particle will continuously change its course as a result of collisions with other particles, as well as with the walls of the container.If the path of a particular gas particle
South Texas College - CHEM - 2301
5.7Effusionand Diffusion213Stated in another way, the relative rates of effusion of two gases at the same temperature and pressure are given by the inverse ratio of the square roots of the masses of the gas particles: In Graham's law the units for mol