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All Textbook Solutions for Chemistry: An Atoms First Approach

143CWP 144CWP A certain flexible weather balloon contains helium gas at a volume of 855 L. Initially, the balloon is at sea level where the temperature is 25C and the barometric pressure is 730 torr. The balloon then rises to an altitude of 6000 ft, where the pressure is 605 torr and the temperature is 15C. What is the change in volume of the balloon as it ascends from sea level to 6000 ft?146CWP A 20.0L nickel container was charged with 0.859 atm of xenon gas and 1.37 atm of fluorine gas at 400C. The xenon and fluorine react to form xenon tetrafluoride. What mass of xenon tetrafluoride can be produced assuming 100% yield?Consider the unbalanced chemical equation below: CaSiO3(s)+HF(g)CaF2(aq)+SiF4(g)+H2O(l) Suppose a 32.9-g sample of CaSiO3 is reacted with 31.8 L of HF at 27.0C and 1.00 atm. Assuming the reaction goes to completion, calculate the mass of the SiF4 and H2O produced in the reaction.149CWP Which of the following statements is(are) true? a. If the number of moles of a gas is doubled, the volume will double, assuming the pressure and temperature of the gas remain constant. b. If the temperature of a gas increases from 25C to 50C, the volume of the gas would double, assuming that the pressure and the number of moles of gas remain constant. c. The device that measures atmospheric pressure is called a barometer. d. If the volume of a gas decreases by one half, then the pressure would double, assuming that the number of moles and the temperature of the gas remain constant.A chemist weighed out 5.14 g of a mixture containing unknown amounts of BaO(s) and CaO(s) and placed the sample in a 1.50-L flask containing CO2(g) at 30.0C and 750. torr. After the reaction to form BaCO3(s) and CaCO3(s) was completed, the pressure of CO2(g) remaining was 230. torr. Calculate the mass percentages of CaO(s) and BaO(s) in the mixture.A mixture of chromium and zinc weighing 0.362 g was reacted with an excess of hydrochloric acid. After all the metals in the mixture reacted, 225 mL dry of hydrogen gas was collected at 27C and 750. torr. Determine the mass percent of Zn in the metal sample. [Zinc reacts with hydrochloric acid to produce zinc chloride and hydrogen gas; chromium reacts with hydrochloric acid to produce chromium(III) chloride and hydrogen gas.]153CP You have an equimolar mixture of the gases SO2 and O2, along with some He, in a container fitted with a piston. The density of this mixture at STP is 1.924 g/L. Assume ideal behavior and constant temperature and pressure. a. What is the mole fraction of He in the original mixture? b. The SO2 and O2 react to completion to form SO3. What is the density of the gas mixture after the reaction is complete?Methane (CH4) gas flows into a combustion chamber at a rate of 200. L/min at 1.50 atm and ambient temperature. Air is added to the chamber at 1.00 atm and the same temperature, and the gases are ignited. a. To ensure complete combustion of CH4 to CO2(g) and H2O(g), three times as much oxygen as is necessary is reacted. Assuming air is 21 mole percent O2 and 79 mole percent N2, calculate the flow rate of air necessary to deliver the required amount of oxygen. b. Under the conditions in part a, combustion of methane was not complete as a mixture of CO2(g) and CO(g) was produced. It was determined that 95.0% of the carbon in the exhaust gas was present in CO2. The remainder was present as carbon in CO. Calculate the composition of the exhaust gas in terms of mole fraction of CO, CO2, O2, N2, and H2O. Assume CH4 is completely reacted and N2 is unreacted.156CP 157CP 158CP You have a helium balloon at 1.00 atm and 25C. You want to make a hot-air balloon with the same volume and same lift as the helium balloon. Assume air is 79.0% nitrogen and 21.0% oxygen by volume. The lift of a balloon is given by the difference between the mass of air displaced by the balloon and the mass of gas inside the balloon. a. Will the temperature in the hot-air balloon have to be higher or lower than 25C? Explain. b. Calculate the temperature of the air required for the hot- air balloon to provide the same lift as the helium balloon at 1.00 atm and 25C. Assume atmospheric conditions are 1.00 atm and 25C.160CP You are given an unknown gaseous binary compound (that is, a compound consisting of two different elements). When 10.0 g of the compound is burned in excess oxygen, 16.3 g of water is produced. The compound has a density 1.38 times that of oxygen gas at the same conditions of temperature and pressure. Give a possible identity for the unknown compound.162CP Calculate w and E when 1 mole of a liquid is vaporized at its boiling point (80.C) and 1.00 atm pressure. H for the vaporization of the liquid is 30.7 kJ/mol at 80.C. Assume the volume of 1 mole of liquid is negligible as compared to the volume of 1 mole of gas at 80.C and 1.00 atm.The preparation of NO2(g) from N2(g) and O2(g) is an endothermie reaction: N2(g)+O2(g)NO2(g)(unbalanced) The enthalpy change of reaction for the balanced equation (with lowest whole-number coefficients) is H = 67.7 kJ. If 2.50 102 mL N2(g) at 100.C and 3.50 atm and 4.50 102 mL O2(g) at 100.C and 3.50 atm are mixed, what amount of heat is necessary to synthesize the maximum yield of NO2(g)?In the presence of nitric acid, UO2+ undergoes a redox process. It is converted to UO22+ and nitric oxide (NO) gas is produced according to the following unbalanced equation: H+(aq)+NO3(aq)+UO2+(aq)NO(g)+UO22+(aq)+H2O(l) If 2.55 102 mL NO(g) is isolated at 29C and 1.5 atm, what amount (moles) of UO2+ was used in the reaction? (Hint: Balance the reaction by the oxidation states method.)Silane, SiH4, is the silicon analogue of methane, CH4. It is prepared industrially according to the following equations: Si(s)+3HC1(g)HSiCl3(l)+H2(g)4HSiCl3(l)SiH4(g)+3SiCl4(l) a. If 156 mL HSiCl3 (d = 1.34 g/mL) is isolated when 15.0 L HC1 at 10.0 atm and 35C is used, what is the percent yield of HSiCl3? b. When 156 mL HSiCl3 is heated, what volume of SiH4 at 10.0 atm and 35C will be obtained if the percent yield of the reaction is 93.1%?167IP 168IP 169MP What are intermolecular forces? How do they differ from intramolecular forces? What are dipole-dipole forces? How do typical dipole-dipole forces differ from hydrogen bonding interactions? In what ways are they similar? What are London dispersion forces? How do typical London dispersion forces differ from dipole-dipole forces? In what ways are they similar? Describe the relationship between molecular size and strength of London dispersion forces. Place the major types of intermolecular forces in order of increasing strength. Is there some overlap? That is, can the strongest London dispersion forces be greater than some dipole-dipole forces? Give an example of such an instance.Define the following terms and describe how each depends on the strength of the intermolecular forces. a. surface tension b. viscosity c. melting point d. boiling point e. vapor pressure Compare and contrast solids, liquids, and gases.4RQ What is a lattice? What is a unit cell? Describe a simple cubic unit cell. How many net atoms are contained in a simple cubic unit cell? How is the radius of the atom related to the cube edge length for a simple cubic unit cell? Answer the same questions for the body-centered cubic unit cell and for the face-centered unit cell.What is closest packing? What is the difference between hexagonal closest packing and cubic closest packing? What is the unit cell for each closest packing?Describe, in general, the structures of ionic solids. Compare and contrast the structure of sodium chloride and zinc sulfide. How many tetrahedral holes and octahedral holes are there per closest packed anion? In zinc sulfide, why are only one-half of the tetrahedral holes filled with cations?9RQ 10RQ Compare and contrast the phase diagrams of water and carbon dioxide. Why doesn t CO2 have a normal melting point and a normal boiling point, whereas water does? The slopes of the solid- liquid lines in the phase diagrams of H2O and CO2 are different. What do the slopes of the solid- liquid lines indicate in terms of the relative densities of the solid and liquid states for each substance? How do the melting points of H2O and CO2 depend on pressure? How do the boiling points of H2O and CO2 depend on pressure? Rationalize why the critical temperature for H2O is greater than that for CO2.It is possible to balance a paper clip on the surface of water in a beaker. lf you add a bit of soap to the water, however, the paper clip sinks. Explain how the paper clip can float and why it sinks when soap is added.2ALQ 3ALQ 4ALQ 5ALQ 6ALQ 7ALQ 8ALQ 9ALQ 10ALQ 11ALQ 12Q In the diagram below, which lines represent the hydrogen bonding? a. the dotted lines between the hydrogen atoms of one water molecule and the oxygen atoms of a different water molecule b. the solid lines between a hydrogen atom and oxygen atom in the same water molecule c. Both the solid lines and dotted lines represent hydrogen bonding. d. There are no hydrogen bonds represented in the diagram.14Q Atoms are assumed to touch in closest packed structures, yet every closest packed unit cell contains a significant amount of empty space. Why?Define critical temperature and critical pressure. In terms of the kinetic molecular theory, why is it impossible for a substance to exist as a liquid above its critical temperature?17Q 18Q 19Q 20Q 21Q A common response to hearing that the temperature in New Mexico is 105F is, Its not that bad; its a dry heat, whereas at the same time the summers in Atlanta, Georgia, are characterized as dreadful, even though the air temperature is typically lower. What role does humidity play in how our bodies regulate temperature?23Q 24Q When wet laundry is hung on a clothesline on a cold winter day, it will freeze but eventually dry. Explain.Cake mixes and other packaged foods that require cooking often contain special directions for use at high elevations. Typically these directions indicate that the food should be cooked longer above 5000 ft. Explain why it takes longer to cook something at higher elevations.You have three covalent compounds with three very different boiling points. All of the compounds have similar molar mass and relative shape. Explain how these three compounds could have very different boiling points.28Q Compare and contrast the structures of the following solids. a. CO2(s) versus H2O(s) b. NaCl(s) versus CsCl(s); see Exercise 69 for the structures.30Q How could you tell experimentally if TiO2 is an ionic solid or a network solid?A common prank on college campuses is to switch the salt and sugar on dining hall tables, which is usually easy because the substances look so much alike. Yet, despite the similarity in their appearance, these two substances differ greatly in their properties, since one is a molecular solid and the other is an ionic solid. How do the properties differ and why?A plot of In (Pvap) versus 1/T (K) is linear with a negative slope. Why is this the case?34Q Identify the most important types of interparticle forces present in the solids of each of the following substances. a. Ar b. HCl c. HF d. CaCl2 e. CH4 f. CO g. NaNO3 36E Predict which substance in each of the following pairs would have the greater intermolecular forces. a. CO2 or OCS b. SeO2 or SO2 c. CH3CH2CH2NH2 or H2NCH2CH2NH2 d. CH3CH3 or H2CO e. CH3OH or H2CO Consider the compounds CI2, HCI. F2, NaF, and HF. Which compound has a boiling point closest to that of argon? Explain.39E Consider the following electrostatic potential diagrams: Rank the compounds from lowest to highest boiling point and explain your answer.In each of the following groups of substances, pick the one that has the given property. Justify your answer. a. highest boiling point: HBr, Kr, or Cl2 b. highest freezing point: H2O, NaCl, or HF c. lowest vapor pressure at 25C: Cl2, Br2, or I2 d. lowest freezing point: N2, CO, or CO2 e. lowest boiling point: CH4, CH3CH3, or CH3CH2CH3 f. highest boiling point: HF, HCl, or HBr g.42E The shape of the meniscus of water in a glass tube is different from that of mercury in a glass tube. Why?44E 45E 46E X rays from a copper X-ray tube ( = 154 pm) were diffracted at an angle of 14.22 degrees by a crystal of silicon. Assuming first-order diffraction (n = 1 in the Bragg equation), what is the interplanar spacing in silicon?The second-order diffraction (n = 2) for a gold crystal is at an angle of22.20 for X rays of 154 pm. What is the spacing between these crystal planes?A topaz crystal has an interplanar spacing (d) of 1.36 (1 = 1 1010 m). Calculate the wavelength of the X ray that should be used if = 15.0 (assume n = 1).X rays of wavelength 2.63 were used to analyze a crystal. The angle of first-order diffraction (n = 1 in the Bragg equation) was 15.55 degrees. What is the spacing between crystal planes, and what would be the angle for second-order diffraction (n = 2)?51E 52E 53E Iridium (Ir) has a face-centered cubic unit cell with an edge length of 383.3 pm. Calculate the density of solid iridium.You are given a small bar of an unknown metal X. You find the density of the metal to be 10.5 g/cm3. An X-ray diffraction experiment measures the edge of the face-centered cubic unit cell as 4.09 (1 = 1010 m). Identify X.A metallic solid with atoms in a face-centered cubic unit cell with an edge length of 392 pm has a density of 21.45 g/cm3. Calculate the atomic mass and the atomic radius of the metal. Identify the metal.Titanium metal has a body-centered cubic unit cell. The density of titanium is 4.50 g/cm3. Calculate the edge length of the unit cell and a value for the atomic radius of titanium. (Hint: In a body-centered arrangement of spheres, the spheres touch across the body diagonal.)Barium has a body-centered cubic structure. If the atomic radius of barium is 222 pm, calculate the density of solid barium.The radius of gold is 144 pm, and the density is 19.32 g/cm3. Does elemental gold have a face-centered cubic structure or a body-centered cubic structure?The radius of tungsten is 137 pm and the density is 19.3 g/cm3. Does elemental tungsten have a face-centered cubic structure or a body-centered cubic structure?What fraction of the total volume of a cubic closest packed structure is occupied by atoms? (Hint: Vsphere=43r3.) What fraction of the total volume of a simple cubic structure is occupied by atoms? Compare the answers.Iron has a density of 7.86 g/cm3 and crystallizes in a body-centered cubic lattice. Show that only 68% of a body-centered lattice is actually occupied by atoms, and determine the atomic radius of iron.63E 64E Selenium is a semiconductor used in photocopying machines. What type of semiconductor would be formed if a small amount of indium impurity is added to pure selenium?66E 67E 68E The structures of some common crystalline substances are shown below. Show that the net composition of each unit cell corresponds to the correct formula of each substance.The unit cell for nickel arsenide is shown below. What is the formula of this compound?Cobalt fluoride crystallizes in a closest packed array of fluoride ions with the cobalt ions filling one-half of the octahedral holes. What is the formula of this compound?The compounds Na2O, CdS, and ZrI4. all can be described as cubic closest packed anions with the cations in tetrahedral holes. What fraction of the tetrahedral holes is occupied for each case?What is the formula for the compound that crystallizes with a cubic closest packed array of sulfur ions, and that contains zinc ions in 18 of the tetrahedral holes and aluminum ions in 12 of the octahedral holes?74E A certain metal fluoride crystallizes in such a way that the fluoride ions occupy simple cubic lattice sites, while the metal ions occupy the body centers of half the cubes. What is the formula of the metal fluoride?The structure of manganese fluoride can be described as a simple cubic array of manganese ions with fluoride ions at the center of each edge of the cubic unit cell. What is the charge of the manganese ions in this compound?The unit cell of MgO is shown below l Does MgO have a structure like that of NaCl or ZnS? If the density of MgO is 3.58 g/cm3, estimate the radius (in centimeters) of the O2 anions and the Mg2+ cations.In solid KCl the smallest distance between the centers of a. potassium ion and a chloride ion is 314 pm. Calculate the length of the edge of the unit cell and the density of KCl, assuming it has the same structure as sodium chloride.The CsCl structure is a simple cubic array of chloride ions with a cesium ion at the center of each cubic array (see Exercise 69). Given that the density of cesium chloride is 3.97 g/cm3, and assuming that the chloride and cesium ions touch along the body diagonal of the cubic unit cell, calculate the distance between the centers of adjacent Cs+ and Cl ions in the solid. Compare this value with the expected distance based on the sizes of the ions. The ionic radius of Cs+ is 169 pm, and the ionic radius of Cl is 181 pm.MnO has either the NaCI type structure or the CsCI type structure (see Exercise 69). The edge length of the MnO unit cell is 4.47 10-8 cm and the density of MnO is 5.28 g/cm3. a. Does MnO crystallize in the NaCl or the CsCl type structure? b. Assuming that the ionic radius of oxygen is 140. pm, estimate the ionic radius of manganese.81E What type of solid will each of the following substances form? a. diamond b. PH3 c. H2 d. Mg e. KCl f. quartz g. NH4NO3 h. SF2 i. Ar j. Cu k. C6H12O6 The memory metal, nitinol, is an alloy of nickel and titanium. It is called a memory metal because after being deformed, a piece of nitinol wire will return to its original shape. The structure of nitinol consists of a simple cubic array of Ni atoms and an inner penetrating simple cubic array of Ti atoms. In the extended lattice, a Ti atom is found at the center of a cube of Ni atoms; the reverse is also true. a. Describe the unit cell for nitinol. b. What is the empirical formula of nitinol? c. What are the coordination numbers (number of nearest neighbors) of Ni and Ti in nitinol?Superalloys have been made of nickel and aluminum. The alloy owes its strength to the formation of an ordered phase, called the gamma-prime phase, in which At atoms are at the corners of a cubic unit cell and Ni atoms are at the face centers. What is the composition (relative numbers of atoms) for this phase of the nickel- aluminum superalloy?Perovskite is a mineral containing calcium, titanium, and oxygen. Two different representations of the unit cell are shown below. Show that both these representations give the same formula and the same number of oxygen atoms around each titanium atom.A mineral crystallizes in a cubic closest packed array of oxygen ions with aluminum ions in some of the octahedral holes and magnesium ions in some of the tetrahedral holes. Deduce the formula of this mineral and predict the fraction of octahedral holes and tetrahedral holes that are filled by the various cations.Materials containing the elements Y, Ba, Cu, and O that are superconductors (electrical resistance equals zero) at temperatures above that of liquid nitrogen were recently discovered. The structures of these materials are based on the perovskite structure. Were they to have the ideal perovskite structure, the superconductor would have the structure shown in pant (a) of the following figure. a. What is the formula of this ideal perovskite material? b. How is this structure related to the perovskite structure shown in Exercise 85? These materials, however, do not act as superconductors unless they are deficient in oxygen. The structure of the actual superconducting phase appears to be that shown in pan (b) of the figure. c. What is the formula of this material?The structures of another class of ceramic, high-temperature superconductors are shown in figures a-d. a. Determine the formula of each of these four superconductors. b. One of the structural features that appears to be essential for high-temperature superconductivity is the presence of planar sheets of copper and oxygen atoms. As the number of sheets in each unit cell increases, the temperature for the onset of superconductivity increases. Order the four structures from lowest to the highest superconducting temperature. c. Assign oxidation states to Cu in each structure assuming Tl exists as Tl3+. The oxidation states of Ca, Ba, and O are assumed to be + 2, + 2, and 2, respectively. d. It also appears that copper must display a mixture of oxidation states for a material to exhibit superconductivity. Explain how this occurs in these materi.als as well as in the superconductor in Exercise 87.Plot the following data and determine Hvap for magnesium and lithium. In which metal is the bonding stronger? Vapor Pressure (mm Hg) Temperature(C) Li Mg 1 750. 620. 10 890. 740. 100 1080. 900. 400 1240. 1040. 760 1310. 1110.From the following data for liquid nitric acid, deter mine its heat of vaporization and normal boiling point. Temperature (C) Vapor Pressure (mm Hg) 0. 14.4 10. 26.6 20. 47.9 30. 81.3 40. 133 50. 208 60. 670.91E 92E 93E Diethyl ether (CH3CH2OCH2CH3) was one of the first chemicals used as an anesthetic. At 34.6C, diethyl ether has a vapor pressure of 760. torr, and at 17.9C, it has a vapor pressure of 400. torr. What is the H of vaporization for diethyl ether?A substance, X, has the following properties: Specific Heat Capacities Hvap 20.kj/mol C(s) 3.0j/gC Hfus 5.0kj/mol C(l) 2.5j/gC bp 75C C(g) 2.5j/gC mp 15C Use the heating-cooling curve below to answer the following questions. a. What is the freezing point of the liquid? b. What is the boiling point of the liquid? c. Which is greater, the heat of fusion or the heat of vaporization? Explain each term and explain how the heating-cooling curve above helps you to answer the question.The molar heat of fusion of sodium metal is 2.60 kJ/mol, whereas its heat of vaporization is 97.0 kJ/mol. a. Why is the heat of vaporization so much larger than the heat of fusion? b. What quantity of heat would be needed to melt 1.00 g sodium at its normal melting point? c. What quantity of heat would be needed to vaporize 1.00 g sodium at its normal boiling point? d. What quantity of heat would be evolved if 1.00 g sodium vapor condensed at its normal boiling point?98E What quantity of energy does it take to convert 0.500 kg ice at 20.C to steam at 250.C? Specific heat capacities: ice, 2.03 J/g C; liquid, 4.2 J/g . C; steam, 2.0 J/g C; Hvap = 40.7 kJ/mol; Hfus = 6.02 kJ/mol.Consider a 75.0-g sample of H2O(g) at 125C. What phase or phases are present when 215 kJ of energy is removed from this sample? (See Exercise 99.)An ice cube tray contains enough water at 22.0C to make 18 ice cubes that each has a mass of 30.0 g. The tray is placed in a freezer that uses CF2Cl2 as a refrigerant. The heat of vaporization of CF2Cl2 is 158 J/g. What mass of CF2Cl2 must be vaporized in the refrigeration cycle to convert all the water at 22.0C to ice at 5.0C? The heat capacities for H2O(s) and H2O(l) are 2.03 J/g .C and 4.18 J/g C, respectively, and the enthalpy of fusion for ice is 6.02 kJ/mol.A 0.250-g chunk of sodium metal is cautiously dropped into a mixture of 50.0 g water and 50.0 g ice, both at 0C. The reaction is 2Na(s)+2H2O(l)2NaOH(aq)+H2(g)H=368kJ Assuming no heat loss to the surroundings, will the ice melt? Assuming the final mixture has a specific heat capacity of 4.18 J/gc, calculate the final temperature. The enthalpy of fusion for ice is 6.02 kJ/mol.103E 104E 105E 106E 107E Consider the following data for xenon: Triple point: 121C, 280 torr Normal melting point: 112C Normal boiling point: 107C Which is more dense, Xe(s) or Xe(l)? How do the melting point and boiling point of xenon depend on pressure?Some of the physical properties of H2O and D2O are as follows: Property H2O D2O Density at 20C (g/ml) 0.997 1.108 Boiling point (C) 100.00 101.41 Melting point (C) 0.00 3.79 Hvap(kJ/mol) 40.7 41.61 Hfus (kJ/mol) 6.02 6.3 Account for the differences. (Note: D is a symbol often used for 2H, the deuterium isotope of hydrogen.)Rationalize the following boiling points:111AE Consider the following enthalpy changes: F+HFFHFH=155kJ/mol(CH3)2C=O+HF+(CH3)2CO---HFH=46kJ/molH2O(g)+HOH(g)+H2O---HOH(inice)H=21kJ/mol How do the strengths of hydrogen bonds vary with the electronegativity of the element to which hydrogen is bonded? Where in the preceding series would you expect hydrogen bonds of the following type to fall?113AE Boron nitride (BN) exists in two forms. The first is a slippery solid formed from the reaction of BCl3 with NH3, followed by heating in an ammonia atmosphere at 750C. Subjecting the first form of BN to a pressure of 85,000 atm at 1800C produces a second form that is the second hardest substance known. Both forms of BN remain solids to 3000C. Suggest structures for the two forms of BN.115AE Argon has a cubic closest packed structure as a solid. Assuming that argon has a radius of 190. pm, calculate the density of solid argon.117AE A 20.0-g sample of ice at 10.0C is mixed with 100.0 g water at 80.0C. Calculate the final temperature of the mixture assuming no heat loss to the surroundings. The heat capacities of H2O(s) and H2O(l) are 2.03 and 4.18 J/gC, respectively, and the enthalpy of fusion for ice is 6.02 kJ/mol.In regions with dry climates, evaporative coolers are used to cool air. A typical electric air conditioner is rated at 1.00 104 Btu/h (1 Btu, or British thermal unit = amount of energy to raise the temperature of 1 lb water by 1F). What quantity of water must be evaporated each hour to dissipate as much heat as a typical electric air conditioner?The critical point of NH3 is 132C and 111 atm, and the critical point of N2 is 147c and 34 atm. Which of these substances cannot be liquefied at room temperature no matter how much pressure is applied? Explain.Which of the following compound(s) exhibit only London dispersion intermolecular forces? Which compound(s) exhibit hydrogen-bonding forces? Considering only the compounds without hydrogen-bonding interactions, which compounds have dipole-dipole intermolecular forces? a. SF4 b. CO2 c. CH3CH2OH d. HF e. ICl5 f. XeF4 Which of the following statements about intermolecular forces is( are) true? a. London dispersion forces are the only type of intermolecular force that nonpolar molecules exhibit. b. Molecules that have only London dispersion forces will always be gases at room temperature (25C). c. The hydrogen-bonding forces in NH3 are stronger than those in H2O. d. The molecules in SO2(g) exhibit dipole-dipole intermolecular interactions. e. CH3CH2CH3 has stronger London dispersion forces than does CH4.123CWP Aluminum has an atomic radius of 143 pm and forms a solid with a cubic closest packed structure. Calculate the density of solid aluminum in g/cm3 Pyrolusite is a mineral containing manganese ions and oxide ions. Its structure can best be described as a body-centered cubic array of manganese ions with two oxide ions inside the unit cell and two oxide ions each on two faces of the cubic unit cell. What is the charge on the manganese ions in pyrolusite?The structure of the compound K2O is best described as a cubic closest packed array of ox.ide ions with the potassium ions in tetrahedral holes. What percent of the tetrahedral holes are occupied in this solid?127CWP Some ice cubes at 0c with a total mass of 403 g are placed in a microwave oven and subjected to 750. W (750. J/s) of energy for 5.00 minutes. What is the final temperature of the water? Assume all the energy of the microwave is absorbed by the water, and assume no heat loss by the water.The enthalpy of vaporization for acetone is 32.0 kJ/mol. The normal boiling point for acetone is 56.5C. What is the vapor pressure of acetone at 23.5C?130CWP When I mole of benzene is vaporized at a constant pressure of 1.00 atm and at its boiling point of 353.0 K, 30.79 kJ of energy (heat) is absorbed and the volume change is +28.90 L. What are E and H for this process?132CP Using the heats of fusion and vaporization for water given in Exercise 99, calculate the change in enthalpy for the sublimation of water: H2O(s)H2O(g) Using the H value given in Exercise 112 and the number of hydrogen bonds formed with each water molecule, estimate what portion of the intermolecular forces in ice can be accounted for by hydrogen bonding.134CP Consider two different organic compounds, each with the formula C2H6O. One of these compounds is a liquid at room conditions and the other is a gas. Write Lewis structures consistent with this observation, and explain your answer. (Hint: The oxygen atom in both structures satisfies the octet rule with two bonds and two lone pairs.)136CP 137CP 138CP 139CP 140CP Mn crystallizes in the same type of cubic unit cell as Cu. Assuming that the radius of Mn is 5.6% larger than the radius of Cu and the density of copper is 8.96 g/cm3, calculate the density of Mn.142CP Some water is placed in a sealed glass container connected to a vacuum pump (a device used to pump gases from a container), and the pump is turned on. The water appears to boil and then freezes. Explain these changes using the phase diagram for water. What would happen to the ice if the vacuum pump was left on indefinitely?The molar enthalpy of vaporization of water at 373 K and 1.00 atm is 40.7 kJ/mol. What fraction of this energy is used to change the internal energy of the water, and what fraction is used to do work against the atmosphere? (Hint: Assume that water vapor is an ideal gas.)145CP Rubidium chloride has the sodium chloride structure at normal pressures but assumes the cesium chloride structure at high pressures. (See Exercise 69.) What ratio of densities is expected for these two forms? Does this change in structure make sense on the basis of simple models? The ionic radius is 148 pm for Rb+ and 181 pm for CI.147IP A metal burns in air at 600c under high pressure to form an oxide with formula MO2. This compound is 23.72% oxygen by mass. The distance between the centers of touching atoms in a cubic closest packed crystal of this metal is 269.0 pm. What is this metal? What is its density?149IP General Zod has sold Lex Luthor what Zod claims to be a new copper-colored form of kryptonite, the only substance that can harm Superman. Lex, not believing in honor among thieves, decided to carry out some tests on the supposed kryptonite. From previous tests, Lex knew that kryptonite is a metal having a specific heat capacity of 0.082 J/gC and a density of 9.2 g/cm3. Lex Luthers first experiment was an attempt to find the specific heat capacity of kryptonite. He dropped a 10 g 3 g sample of the metal into a boiling water bath at a temperature of 100.0C 0.2C. He waited until the metal had reached the bath temperature and then quickly transferred it to I 00 g 3 g of water that was contained in a calorimeter at an initial temperature of 25.0C 0.2C. The final temperature of the metal and water was 25.2C. Based on these results, is it possible to distinguish between copper and kryptonite? Explain. When Lex found that his results from the first experiment were inconclusive, he decided to determine the density of the sample. He managed to steal a better balance and determined the mass of another portion of the purported kryptonite to be 4 g 1 g. He dropped this sample into water contained in a 25-mL graduated cylinder and found that it displaced a volume of 0.42 mL 0.02 mL. Is the metal copper or kryptonite? Explain. Lex was finally forced to determine the crystal structure of the metal General Zod had given him. He found that the cubic unit cell contained four atoms and had an edge length of 600. pm. Explain how this information enabled Lex to identify the metal as copper or kryptonite. Will Lex be going after Superman with the kryptonite or seeking revenge on General Zod? What improvements could he have made in his experimental techniques to avoid performing the crystal structure determination?1RQ Using KF as an example, write equations that refer to Hsoln and Hhyd Lattice energy was defined in Chapter 3 as H for the reaction K+(g) + F (g) KF(s). Show how you would utilize Hesss law to calculate Hso1n from Hhyd and HLE for KF, where HLE = lattice energy. Hsoln for KF, as for other soluble ionic compounds, is a relatively small number. How can this be since Hhyd and HLE are relatively large negative numbers?3RQ 4RQ Define the terms in Raoults law. Figure 10-9 illustrates the net transfer of water molecules from pure water to an aqueous solution of a nonvolatile solute. Explain why eventually all of the water from the beaker of pure water will transfer to the aqueous solution. If the experiment illustrated in Fig. 10-9 was performed using a volatile solute, what would happen? How do you calculate the total vapor pressure when both the solute and solvent are volatile?In terms of Raoults law, distinguish between an ideal liquid-liquid solution and a nonideal liquid-liquid solution. lf a solution is ideal, what is true about Hsoln, T for the solution formation, and the interactive forces within the pure solute and pure solvent as compared to the interactive forces within the solution? Give an example of an ideal solution. Answer the previous two questions for solutions that exhibit either negative or positive deviations from Raoults law.7RQ 8RQ 9RQ 10RQ 1ALQ 2ALQ 3ALQ 4ALQ You have read that adding a solute to a solvent can both increase the boiling point and decrease the freezing point. A friend of yours explains it to you like this: The solute and solvent can be like salt in water. The salt gets in the way of freezing in that it blocks the water molecules from joining together. The salt acts like a strong bond holding the water molecules together so that it is harder to boil. What do you say to your friend?6ALQ 7ALQ 8ALQ 9ALQ 10ALQ Rubbing alcohol contains 585 g isopropanol (C3H7OH) per liter (aqueous solution). Calculate the molarity.12SR 13SR 14SR Calculate the sodium ion concentration when 70.0 mL of 3.0 M sodium carbonate is added to 30.0 mL of 1.0 M sodium bicarbonate.Write equations showing the ions present after the following strong electrolytes are dissolved in water. a. HNO3 b. Na2SO4 c. Al(NO3)3 d. SrBr2 e. KClO4 f. NH4Br g. NH4NO3 h. CuSO4 i. NaOH 17Q The weak electrolyte NH3(g) does not obey Henrys law. Why? O2(g) obeys Henrys law in water but not in blood (an aqueous solution). Why?The two beakers in the sealed container illustrated below contain pure water and an aqueous solution of a volatile solute. If the solute is less volatile than water, explain what will happen to the volumes in the two containers as time passes.The following plot shows the vapor pressure of various solutions of components A and B at some temperature. Which of the following statements is false concerning solutions of A and B? a. The solutions exhibit negative deviations from Raoults law. b. Hso1n for the solutions should be exothermic. c. The intermolecular forces are stronger in solution than in either pure A or pure B. d. Pure liquid B is more volatile than pure liquid A. e. The solution with XB = 0.6 will have a lower boiling point than either pure A or pure B.21Q 22Q 23Q 24Q 25Q 26Q Explain the terms isotonic solution, crenation, and hemolysis.28Q 29E 30E Common commercial acids and bases are aqueous solutions with the following properties: Density (g/cm3) Mass Percent of Solute Hydrochloric acid 1.19 38 Nitric acid 1.42 70. Sulfuric acid 1.84 95 Acetic acid 1.05 99 Ammonia 0.95 28 Calculate the molarity, molality, and mole fraction of each of the preceding reagents.In lab you need to prepare at least 100 mL of each of the following solutions. Explain how you would proceed using the given information. a. 2.0 m KCl in water (density of H2O = 1.00 g/cm3) b. 15% NaOH by mass in water (d = 1.00 g/cm3) c. 25% NaOH by mass in CH3OH (d = 0.79 g/cm3) d. 0.10 mole fraction of C6H12O6 in water (d = 1.00 g/cm3)33E 34E 35E Calculate the molarity and mole fraction of acetone in a 1.00-m solution of acetone (CH3COCH3) in ethanol (C2H5OH). (Density of acetone = 0.788 g/cm3; density of ethanol = 0.789 g/cm3.) Assume that the volumes of acetone and ethanol add.37E 38E 39E 40E Although Al(OH)3 is insoluble in water, NaOH is very soluble. Explain in terms of lattice energies.42E 43E 44E 45E Which ion in each of the following pairs would you expect to be more strongly hydrated? Why? a. Na+ or Mg2+ b. Mg2+ or Be2+ c. Fe2+ or Fe3+ d. F or Br e. Cl or ClO4 f. ClO4 or SO42 Rationalize the trend in water solubility for the following simple alcohols: Alcohol Solubility (g/100 g H2O at 20C) Methanol, CH3OH Soluble in all proportions Ethanol, CH3CH2OH Soluble in all proportions Propanol, CH3CH2CH2OH Soluble in all proportions Butanol, CH3(CH2)2CH2OH 8.14 Pentanol. CH3(CH2)3CH2OH 2.64 Hexanol, CH3(CH2)4CH2OH 0.59 Heptanol, CH3(CH2)5CH2OH 0.09 48E The solubility of nitrogen in water is 8.21 104 mol/L at 0C when the N2 pressure above water is 0.790 atm. Calculate the Henrys law constant for N2 in units of mol/L atm for Henrys law in the form C = kP, where C is the gas concentration in mol/L. Calculate the solubility of N2 in water when the partial pressure of nitrogen above water is 1.10 atm at 0C.Calculate the solubility of O2 in water at a partial pressure of O2 of 120 torr at 25C. The Henrys law constant for O2 is 1.3 103 mol/L atm for Henrys law in the form C = kP, where C is the gas concentration (mol/L).Glycerin, C3H8O3, is a nonvolatile liquid. What is the vapor pressure of a solution made by adding 164 g glycerin to 338 mL H2O at 39.8C? The vapor pressure of pure water at 39.8C is 54.74 torr and its density is 0.992 g/cm3.52E The normal boiling point of diethyl ether is 34.5C. A solution containing a nonvolatile solute dissolved in diethyl ether has a vapor pressure of 698 torr at 34.5C. What is the mole fraction of diethyl ether in this solution?At a certain temperature, the vapor pressure of pure benzene (C6H6) is 0.930 atm. A solution was prepared by dissolving 10.0 g of a nondissociating, nonvolatile solute in 78.11 g of benzene at that temperature. The vapor pressure of the solution was found to be 0.900 atm. Assuming the solution behaves ideally, determine the molar mass of the solute.A solution is made by dissolving 25.8 g urea (CH2N2O), a non-electrolyte, in 275 g water. Calculate the vapor pressures of this solution at 25C and 45C. (The vapor pressure of pure water is 23.8 torr at 25C and 71.9 torr at 45C.)A solution of sodium chloride in water has a vapor pressure of 19.6 torr at 25C. What is the mole fraction of solute particles in this solution? What would be the vapor pressure of this solution at 45C? The vapor pressure of pure water is 23.8 torr at 25C and 71.9 torr at 45C, and assume sodium chloride exists as Na+ and Cl ions in solution.57E A solution is prepared by mixing 0.0300 mole of CH2Cl2 and 0.0500 mole of CH2Br2 at 25C. Assuming the solution is ideal, calculate the composition of the vapor (in terms of mole fractions) at 25C. At 25C, the vapor pressures of pure CH2Cl2 and pure CH2Br2 are 133 and 11.4 torr, respectively.What is the composition of a methanol (CH3OH)-propanol (CH3CH2CH2OH) solution that has a vapor pressure of 174 torr at 40C? At 40C, the vapor pressures of pure methanol and pure propanol are 303 and 44.6 torr, respectively. Assume the solution is ideal.Benzene and toluene form an ideal solution. Consider a solution of benzene and toluene prepared at 25C. Assuming the mole fractions of benzene and toluene in the vapor phase are equal, calculate the composition of the solution. At 25C the vapor pressures of benzene and toluene are 95 and 28 torr, respectively.Which of the following will have the lowest total vapor pressure at 25C? a. pure water (vapor pressure = 23.8 torr at 25C) b. a solution of glucose in water with C6H12O6=0.01 c. a solution of sodium chloride in water with NaCl = 0.01 d. a solution of methanol in water with CH3OH=0.2 (Consider the vapor pressure of both methanol [143 torr at 25C] and water.)62E Match the vapor pressure diagrams with the solute-solvent combinations and explain your answers. a. and b. and c. and d. and The vapor pressures of several solutions of water-propanol (CH3CH2CH2OH) were determined at various compositions, with the following data collected at 45C: H2O Vapor pressure(torr) 0 74.0 0.15 77.3 0.37 80.2 0.54 81.6 0.69 80.6 0.83 78.2 1.00 71.9 a. Are solutions of water and propanol ideal? Explain. b. Predict the sign of Hsoln for water-propanol solutions. c. Are the interactive forces between propanol and water molecules weaker than, stronger than, or equal to the interactive forces between the pure substances? Explain. d. Which of the solutions in the data would have the lowest normal boiling point?A solution is prepared by dissolving 27.0 g urea, (NH2)CO, in 150.0 g water. Calculate the boiling point of the solution. Urea is a nonelectrolyte.A 2.00-g sample of a large biomolecule was dissolved in 15.0 g carbon tetrachloride. The boiling point of this solution was determined to be 77 .85C. Calculate the molar mass of the biomolecule. For carbon tetrachloride, the boiling-point constant is 5.03C kg/mol, and the boiling point of pure carbon tetrachloride is 76.50C.What mass of glycerin (C3H8O3), a nonelectrolyte, must be dissolved in 200.0 g water to give a solution with a freezing point of 1.50C?The freezing point of 1-butanol is 25.50C and Kf is 9.1C kg/mol. Usually t-butanol absorbs water on exposure to air. If the freezing point of a 10.0-g sample of t-butanol is 24.59C, how many grams of water are present in the sample?69E What volume of ethylene glycol (C2H6O2), a nonelectrolyte, must be added to 15.0 L water to produce an antifreeze solution with a freezing point of 25.0C? What is the boiling point of this solution? (The density of ethylene glycol is 1.11 g/cm3, and the density of water is 1.00 g/cm3.)Reserpine is a natural product isolated from the roots of the shrub Rauwolfia serpenlina. It was first synthesized in 1956 by Nobel Prize winner R. B. Woodward. It is used as a tranquilizer and sedative. When 1.00 g reserpine is dissolved in 25.0 g camphor, the freezing-point depression is 2.63C (Kr for camphor is 40.C kg/mol). Calculate the molality of the solution and the molar mass of reserpine.A solution contains 3.75 g of a nonvolatile pure hydrocarbon in 95 g acetone. The boiling points of pure acetone and the solution are 55.95C and 56.50C, respectively. The molal boiling-point constant of acetone is 1.71 C kg/mol. What is the molar mass of the hydrocarbon?a. Calculate the freezing-point depression and osmotic pressure at 25C of an aqueous solution containing 1.0 g/L of a protein (molar mass = 9.0 104 g/mol) if the density of the solution is 1.0 g/cm3. b. Considering your answer to part a, which colligative property, freezing-point depression or osmotic pressure, would be better used to determine the molar masses of large molecules? Explain.Erythrocytes are red blood cells containing hemoglobin. In a saline solution they shrivel when the salt concentration is high and swell when the salt concentration is low. In a 25C aqueous solution of NaCl, whose freezing point is 0.406C, erythrocytes neither swell nor shrink. If we want to calculate the osmotic pressure of the solution inside the erythrocytes under these conditions, what do we need to assume? Why? Estimate how good (or poor) of an assumption this is. Make this assumption and calculate the osmotic pressure of the solution inside the erythrocytes.75E 76E 77E 78E Consider the following solutions: 0.010 m Na3PO4 in water 0.020 m CaBr2 in water 0.020 m KCl in water 0.020 m HF in water (HF is a weak acid.) a. Assuming complete dissociation of the soluble salts, which solution(s) would have the same boiling point as 0.040 m C6H12O6 in water? C6H12O6 is a nonelectrolyte. b. Which solution would have the highest vapor pressure at 28C? c. Which solution would have the largest freezing-point depression?From the following: pure water solution of C12H22O11 (m = 0.01) in water solution of NaCl (m = 0.01) in water solution of CaCl2 (m = 0.01) in water Choose the one with the a. highest freezing point. b. lowest freezing point. c. highest boiling point. d. lowest boiling point. e. highest osmotic pressure.81E 82E 83E Consider the following representations of an ionic solute in water. Which flask contains MgSO4, and which flask contains NaCl? How can you tell?85E 86E Use the following data for three aqueous solutions of CaCl2 to calculate the apparent value of the vant Hoff factor. Molality Freezing-Point Deperssion(C) 0.0225 0.110 0.0910 0.440 0.278 1.330 The freezing-point depression of a 0.091-m solution of CsCl is 0.320C. The freezing-point depression of a 0.091-m solution of CaCl2 is 0.440C. In which solution does ion association appear to be greater? Explain.89E A 0.500-g sample of a compound is dissolved in enough water to form 100.0 mL of solution. This solution has an osmotic pressure of 2.50 atm at 25C. If each molecule of the solute dissociates into two particles (in this solvent), what is the molar mass of this solute?The solubility of benzoic acid (HC7H5O2), is 0.34 g/100 mL in water at 25C and is 10.0 g/100 mL in benzene (C6H6) at 25C. Rationalize this solubility behavior. (Hint: Benzoic acid forms a dimer in benzene.) Would benzoic acid be more or less soluble in a 0.1-M NaOH solution than it is in water? Explain.92AE 94AE Explain the following on the basis of the behavior of atoms and/or ions. a. Cooking with water is faster in a pressure cooker than in an open pan. b. Salt is used on icy roads. c. Melted sea ice from the Arctic Ocean produces fresh water. d. CO2(s) (dry ice) does not have a normal boiling point under normal atmospheric conditions, even though CO2 is a liquid in fire extinguishers. e. Adding a solute to a solvent extends the liquid phase over a larger temperature range.96AE 97AE 98AE A solution is made by mixing 50.0 g acetone (CH3COCH3) and 50.0 g methanol (CH3OH). What is the vapor pressure of this solution at 25C? What is the composition of the vapor expressed as a mole fraction? Assume ideal solution and gas behavior. (At 25C the vapor pressures of pure acetone and pure methanol are 271 and 143 torr, respectively.) The actual vapor pressure of this solution is 161 torr. Explain any discrepancies.100AE 101AE 102AE An unknown compound contains only carbon, hydrogen, and oxygen. Combustion analysis of the compound gives mass percents of 31.57% C and 5.30% H. The molar mass is determined by measuring the freezing-point depression of an aqueous solution. A freezing point of 5.20C is recorded for a solution made by dissolving 10.56 g of the compound in 25.0 g water. Determine the empirical formula, molar mass, and molecular formula of the compound. Assume that the compound is a nonelectrolyte.104AE

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