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All Textbook Solutions for Chemistry by OpenStax (2015-05-04)

Predict the electron pair geometry and the molecular structure of each of the following ions: (a) H3O+ (b) PCl4 (c) SnCl3 (d) BrCl4 (e) ICl3 (f) XeF4 (g) SF2 Identify the electron pair geometry and the molecular structure of each of the following molecules: (a) CINO (N is the central atom) (b) CS2 (c) Cl2CO (C is the central atom) (d) Cl2SO (S is the central atom) (e) SO2F2 (S is the central atom) (f) XeO2F2 (Xe is the central atom) (g) CIOF2+ (Cl is the central atom)Predict the electron pair geometry and the molecular structure of each of the following: (a) IOF5 (I is the central atom) (b) POCl3 (P is the central atom) (c) Cl2SeO (Se is the central atom) (d) CISO+ (S is the central atom) (e) F2SO (S is the central atom) (f) NO2 (g) SiO44 Which of the following molecules and ions contain polar bonds? Which of these molecules and ions have dipole moments? (a) CIF5 (b) CIO2 (c) TeCI42 (d) PCl3 (e) SeF4 (f) PH2 (g) XeF2 Which of these molecules and ions contain polar bonds? Which of these molecules and ions have dipole moments? (a) H3O (b) PCl4 (c) SnCl3 (d) BrCl4 (e) ICI3 (f) XeF4 (g) SF2 Which of the following molecules have dipole moments? (a) CS2 (b) SeS2 (c) CCl2F2 (d) PCl3 (P is the central atom) (e) ClNO (N is the central atom)Identify the molecules with a dipole moment: (a) SF4 (b) CF4 (c) Cl2CCBr2 (d) CH3Cl (e) H2CO The molecule XF3 has a dipole moment. Is X boron or phosphorus?The molecule XCl2 has a dipole moment. Is X beryllium or sulfur?Is the Cl2BBCl2 molecule polar or nonpolar?There are three possible structures for PCl2F3 with phosphorus as the central atom. Draw them and discuss how measurements of dipole moments could help distinguish among them.Describe the molecular structure around the indicated atom or atoms: (a) the sulfur atom in sulfuric acid, H2SO4[(HO)2SO2] (b) the chlorine atom in chloric acid, HClO3[HOClO2] (c) the oxygen atom in hydrogen peroxide, HNO3[HONO2] (d) the nitrogen atom in nitric acid, HNO3[HONO2] (e) the oxygen atom in the OH group in nitric acid, HNO3[HONO2] (f) the central oxygen atom in the ozone molecule, O3 (g) each of the carbon atoms in propyne, CH3CCH (h) the carbon atom in Freon, CCl2F2 (i) each of the carbon atoms in aliene, H2CCH2 Draw the Lewis structures and predict the shape of each compound or ion: (a) CO2 (b) NO2 (c) SO3 (d)SO32 A molecule with the formula AB2, in which A and B represent different atoms, could have one of three different shapes. Sketch and name the three different shapes that this molecule might have. Give an example of a molecule or ion for each shape.A molecule with the formula AB3, in which A and B represent different atoms, could have one of three different shapes. Sketch and name the three different shapes that this molecule might have. Give an example of a molecule or ion that has each shape.Draw the Lewis electron dot structures for these molecules, including resonance structures where appropriate: (a) CS32 (b) CS2 (c) CS (d) predict the molecular shapes for CS32 and CS2 and explain how you arrived at your predictions What is the molecular structure of the stable form of FNO2? (N is the central atom.)A compound with a molar mass of about 42 g/mol contains 85.7% carbon and 14.3% hydrogen. What is its molecular structure?Use the simulation (http://openstaxcollege.org/l/16MolecPolarity) to perform the following exercises for a two-atom molecule: (a) Adjust the electronegativity value so the bond dipole is pointing toward B. Then determine what the electronegativity values must be to switch the dipole so that it points toward A. (b) With a partial positive charge on A, turn on the electric field and describe what happens. (c) With a small partial negative charge on A, turn on the electric field and describe what happens. (d) Reset all, and then with a large partial negative charge on A, turn on the electric field and describe what happens.Use the simulation (http://openstaxcollege.org/l/16MolecPolarity) to perform the following exercises for a real molecule. You may need to rotate the molecules in three dimensions to see certain dipoles. (a) Sketch the bond dipoles and molecular dipole (if any) for O3 Explain your observations. (b) Look at the bond dipoles for NH3. Use these dipoles to predict whether N or H is more electronegative. (c) Predict whether there should be a molecular dipole for NH3 and, if so, in which direction it will point. Check the molecular dipole box to test your hypothesis.Use the Molecule Shape simulator (http://openstaxcollege.org/I/6MolecShape) to build a molecule. Starting with the central atom, click on the double bond to add one double bond. Then add one single bond and one lone pair. Rotate the molecule to observe the complete geometry. Name the electron group geometry and molecular structure and predict the bond angle. Then click the check boxes at the bottom and right of the simulator to check your answers.Use the Molecule Shape simulator (http://openstaxcollege.org/l/16MolecShape) to explore real molecules. On the Real Molecules tab, select H2O. Switch between the real and model modes. Explain the difference observed.Use the Molecule Shape simulator (http://openstaxcollege.org/l/16MolecShape) to explore real molecules. On the Real Molecules tab, select model mode and S2O. What is the model bond angle? Explain whether the real bond angle should be larger or smaller than the ideal model angle.Explain how and bonds are similar and how they are different.Draw a curve that describes the energy of a system with H and Cl atoms at varying distances. Then, find the minimum energy of this curve two ways. (a) Use the bond energy found in Table 8.1 to calculate the energy for one single HCl bond (Hint: How many bonds are in a mole?) (b) Use the enthalpy of reaction and the bond energies for H2 and Cl2 to solve for the energy of one mole of HCl bonds. H2(g)+Cl2(g)2HCl(g)Hrxn=184.7kJ/mol Explain why bonds occur at specific average bond distances instead of the atoms approaching each other infinitely close.Use valence bond theory to explain the bonding in F2, HF, and CIBr. Sketch the overlap of the atomic orbitals involved in the bonds.Use valence bond theory to explain the bonding in O2. Sketch the overlap of the atomic orbitals involved in the bonds in O2.How many and bonds are present in the molecule HCN?A friend tells you N2 has three bonds due to overlap of the three p -orbitals on each N atom. Do you agree?Draw the Lewis structures for CO2 and CO, and predict the number of o and bonds for each molecule. (a) CO2 (b) CO Why is the concept of hybridization required in valence bond theory?Give the shape that describes each hybrid orbital set: (a) sp2 (b) sp3d (c) sp (d) sp3d2 Explain why a carbon atom cannot form five bonds using sp3d hybrid orbitals.What is the hybridization of the central atom in each of the following? (a) BeH2 (b) SF6 (c) PO43 (d) PCl5 A molecule with the formula AB3 could have one of four different shapes. Give the shape and the hybridization of the central A atom for each.Methionine, CH3SCH2CH2CH(NH2)CO2H, is an amino acid found in proteins. The Lewis structure of this compound is shown below. What is the hybridization type of each carbon, oxygen, the nitrogen, and the sulfur?Sulfuric acid is manufactured by a series of reactions represented by the following equations: S8(s)+8O2(g)8SO2(g)2SO2(g)+O2(g)2SO3(g)SO3(g)+H2O(l)H2SO4(l) Draw a Lewis structure, predict the molecular geometry by VSEPR, and determine the hybridization of sulfur for the following: (a) circular SO2 molecule (b) SO3 molecule (c) SO3 molecule (d) H2SO4 molecule (the hydrogen atoms are bonded to oxygen atoms)Two important industrial chemicals, ethene, C2H4, and propene, C3H6, are produced by the steam (or thermal) cracking process: 2C3H8(g)C2H4(g)+C3H6(g)+H2(g) For each of the four carbon compounds, do the following: (a) Draw a Lewis structure. (b) Predict the geometry about the carbon atom. (c) Determine the hybridization of each type of carbon atom.For many years after they were discovered, it was believed that the noble gases could not form compounds. Now we know that belief to be incorrect. A mixture of xenon and fluorine gases, confined in a quartz bulb and placed on a windowsill, is found to slowly produce a white solid. Analysis of the compound indicates that it contains 77.55% Xe and 22.45% F by mass. (a) What is the formula of the compound? (b) Write a Lewis structure for the compound. (c) Predict the shape of the molecules of the compound. (d) What hybridization is consistent with the shape you predicted?Consider nitrous acid, HNO2 (HONO). (a) Write a Lewis structure. (b) What are the electron pair and molecular geometries of the internal oxygen and nitrogen atoms in the HNO2 molecule? (c) What is the hybridization on the internal oxygen and nitrogen atoms in HNO2?Strike-anywhere matches contain a layer of KClO3 and a layer of P4S3. The heat produced by the friction of striking the match causes these two compounds to react vigorously, which sets fire to the wooden stem of the match. KCIO3 contains the ClO3 ion. P4S3 is an unusual molecule with the skeletal structure. (a) Write Lewis structures for P4S3 and the ClO3 ion. (b) Describe the geometry about the P atoms, the S atom, and the Cl atom in these species. (c) Assign a hybridization to the P atoms, the S atom, and the Cl atom in these species. (d) Determine the oxidation states and formal charge of the atoms in P4S3 and the ClO3 ion.Identify the hybridization of each carbon atom in the following molecule. (The arrangement of atoms is given; you need to determine how many bonds connect each pair of atoms.)Write Lewis structures for NF3 and PP5. On the basis of hybrid orbitals, explain the fact that NF3, PP3, and PP5 are stable molecules, but NP5 does not exist.In addition to NF3, two other fluoro derivatives of nitrogen are known: N2F4 and N2F2. What shapes do you predict for these two molecules? What is the hybridization for the nitrogen in each molecule?The bond energy of a C—C single bond averages 347 kJ mol-1; that of a CC triple bond averages 839 kJ mol-1. Explain why the triple bond is not three times as strong as a single bond.For the carbonate ion, CO32, draw all of the resonance structures. Identify which orbitals overlap to create each bond.A useful solvent that will dissolve salts as well as organic compounds is the compound acetonitrile, H3CCN. It is present in paint strippers. (a) Write the Lewis structure for acetonitrile, and indicate the direction of the dipole moment in the molecule. (b) Identify the hybrid orbitals used by the carbon atoms in the molecule to form bonds. (c) Describe the atomic orbitals that form the n bonds in the molecule. Note that it is not necessary to hybridize the nitrogen atom.For the molecule allene, H2C=C=CH2, give the hybridization of each carbon atom. Will the hydrogen atoms be in the same plane or perpendicular planes?Identify the hybridization of the central atom in each of the following molecules and ions that contain multiple bonds: (a) ClNO (N is the central atom) (b) CS2 (c) Cl2CO (C is the central atom) (d) CI2SO (S is the central atom) (e) SO2F2 (S is the central atom) (f) XeO2F2 (Xe is the central atom) (g) CIOF2 + (Cl is the central atom)Describe the molecular geometry and hybridization of the N, P, or S atoms in each of the following compounds. (a) H3PO4, phosphoric acid, used in cola soft dunks (b) NH4NO3, ammonium nitrate, a fertilizer and explosive (c) S2Cl2, disulfur dichioride, used in vulcanizing rubber (d) K4[O3POPO3], potassium pyrophosphate, an ingredient in some toothpastes For each of the following molecules, indicate the hybridization requested and whether or not the electrons will be delocalized: (a) ozone (O3) central O hybridization (b) carbon dioxide (CO2) central C hybridization (c) nitrogen dioxide (NO2) central N hybridization (d) phosphate Ion (PO43) central P hybridization For each of the following structures, determine the hybridization requested and whether the electrons will be delocalized: (a) Hybridization of each carbon (b) Hybridization of sulfur (c) All atoms Draw the orbital diagram for carbon in CO2 showing how many carbon atom electrons are in each orbital.Sketch the distribution of electron density in the bonding and antibonding molecular orbitals formed from two s orbitals and from two p orbitals.How are the following similar, and how do they differ? (a) molecular orbitals and molecular orbitals (b) for an atomic orbital and for a molecular orbital (c) bonding orbitals and antibonding orbitals If molecular orbitals are created by combining five atomic orbitals from atom A and five atomic orbitals from atom B combine, how many molecular orbitals will result?Can a molecule with an odd number of electrons ever be diamagnetic? Explain why or why not.Can a molecule with an even number of electrons ever be paramagnetic? Explain why or why not.Why are bonding molecular orbitals lower in energy than the parent atomic orbitals?Calculate the bond order for an ion with this configuration: ( 2s)2(* 2s)2( 2px)2( 2px, 2pz)4( * 2py, * 2pz)3 Explain why an electron in the bonding molecular orbital in the H2 molecule has a lower energy than an electron in the 1s atomic orbital of either of the separated hydrogen atoms.Predict the valence electron molecular orbital configurations for the following, and state whether they will be stable or unstable ions. (a) Na,2+ (b) Mg,2 (c) AI,2 (d) Si,2 (e) p2+ (f) s,2 (g) F,2 (h) Ar,2 40. Predict the valence electron molecular orbital configurations for the following, and state whether they will be stable or unstable ions. (a) Na22+ (b) Mg22+ (c) Al22+ (d) Si22+ (e) P22+ (f) S22+ (g) F22+ (h) Ar22+Determine the bond order of each member of the following groups, and determine which member of each group is predicted by the molecular orbital model to have the strongest bond. (a) H2,H2+,H2 (b) O2,O22+,O22 (c) Li2,Be2+,Be2 (d) F2,F2+,F2 (e) N2,N2+,N2 For the first ionization energy for an N2 molecule, what molecular orbital is the electron removed from?Compare the atomic and molecular orbital diagrams to identify the member of each of the following pairs that has the highest firs ionization energy (the most tightly bound electron) in the gas phase: (a) H and H2 (b) N and N2 (c) O and O2 (d) C and C2 (e) B and B2 Which of the period 2 homonuclear diatomic molecules are predicted to be paramagnetic?A friend tells you that the 2s orbital for fluorine starts off at a much lower energy than the 2s orbital for lithium, so the resulting 2s molecular orbital in F2 is more stable than in Li2. Do you agree?True or false: Boron contains 2s22p1 valence electrons, so only one p orbital is needed to form molecular orbitals.What charge would be needed on F2 to generate an ion with a bond order of 2?Predict whether the MO diagram S2 would show s-p mixing or not.Explain why N22+ is diamagnetic, while O24+, which has the same number of valence electrons, is paramagnetic.Using the MO diagrams, predict the bond order for the stronger bond In each pair: (a) B2orB2+ (b) F2orF2+ (c) O2orO22+ (d) C2+orC2 Why are sharp knives more effective than dull knives (Hint: think about the definition of pressure)?Why do some small bridges have weight limits that depend on how many wheels or axles the crossing vehicle has?Why should you roll or belly-crawl rather than walk across a thinly-frozen pond?A typical barometric pressure in Redding. California, is about 750 mm Hg. Calculate this pressure in atm and kPa.A typical barometric pressure in Denver, Colorado, is 615 mm Hg. What is this pressure in atmospheres and kilopascals?A typical barometric pressure in Kansas City is 740 torr. What is this pressure in atmospheres, in millimeters of mercury, and in kilopascals?Canadian tire pressure gauges are marked in units of kilopascals. What reading on such a gauge corresponds to 32 psi?Dining the Viking landings on Mars, the atmospheric pressure was determined to be on the average about 6.50 millibars (1 bar 0.987 atm). What is that pressure in torr and kPa?The pressure of the atmosphere on the surface of the planet Venus is about 88.8 atm. Compare that pressure in psi to the normal pressure on earth at sea level in psi.A medical laboratory catalog describes the pressure in a cylinder of a gas as 14.82 MPa. What is the pressure of this gas in atmospheres and torr?Consider this scenario and answer the following questions: On a mid-August day in the northeastern United States, the following information appeared in the local newspaper: atmospheiic pressure at sea level 29.97 in. Hg, 1013.9 mbar. (a) What was the pressure in kPa? (b) The pressure near the seacoast in the northeastern United States is usually reported near 30.0 in. Hg. During a hurricane, the pressure may fall to near 28.0 in. Hg. Calculate the drop in pressure iii ton.Why is it necessary to use a nonvolatile liquid in a barometer or manometer?The pressure of a sample of gas is measured at sea level with a closed-end manometer. The liquid in the manometer is mercury. Determine the pressure of the gas in: (a) torr (b) Pa (c) bar The pressure of a sample of gas is measured with an open-end manometer, partially shown to the right. The liquid in the manometer is mercury. Assuming atmospheric pressure is 29.92 in. Hg. determine the pressure of the gas in: (a) torr (b) Pa (c) bar The pressure of a sample of gas is measured at sea level with an open-end mercury manometer. Assuming atmospheric pressure is 760.0 mm Hg. determine the pressure of the gas in: (a) mm Hg (b) atm (c) kPa The pressure of a sample of gas ¡s measured a sea level with an open-end mercury manometer. Assuming atmospheric pressure is 760 mm Hg. determine the pressure of the gas in: (a) mm Hg (b) atm (c) kPa How would the use of a volatile liquid affect the measurement of a gas using open-ended manometers vs. closed-end manometers?Sometimes leaving a bicycle in the sun on a hot day will cause a blowout. Why?Explain how the volume of the bubbles exhausted by a scuba diver (Figure 9.16) change as they rise to the surface, assuming that they remain intact.One way to state Boyle’s law is All other things being equal, the pressure of a gas is inversely proportional to its volume. (a) What is the meaning of the term inversely proportional? (b) What are the other things that must be equal?An alternate way to state Avogadro’s law is A1l other things being equal, the number of molecules in a gas is directly proportional to the volume of the gas. (a) What is the meaning of the term directly proportional? (b) What are the other things that must be equal How would the graph in Figure 9.12 change if the number of moles of gas in the sample used to determine the curve were doubled?How would the graph in Figure 9.13 change if the number of moles of gas in the sample used to determine the curve were doubled?In addition to the data found in Figure 9.13, what other information do we need to find the mass of the sample of air used to determine the graph?Determine the volume of 1 mol of CH4 gas at 150 K and 1 atm, using Figure 9.12.Determine the pressure of the gas in the syringe shown in Figure 9.13 when its volume is 12.5 mL, using: (a) the appropriate graph (b) Boyle’s law A spray can is used until it is empty except for the propellant gas, which has a pressure of 1344 torr at 23 C. If the can is thrown into a fire (T = 472 C), what will be the pressure in the hot can?What is the temperature of an 11.2-L sample of carbon monoxide, CO, at 744 torr if it occupies 13.3 L at 55 C and 74-4 torr?À 2.50-L volume of hydrogen measured at —196 C is warmed to 100 C. Calculate the volume of the gas at the higher temperature, assuming no change in pressure.A balloon inflated with three breaths of air has a volume of 1.7 L. At the same temperature and pressure, what is the volume of the balloon if five more same-sized breaths are added to the balloon?A weather balloon contains 8.80 moles of helium at a pressure of 0.992 atm and a temperature of 25 C at ground level. What is the volume of the balloon under these conditions?The volume of an automobile air bag was 66.8 L when inflated at 25 C with 77.8 g of nitrogen gas. What was the pressure in the bag in kPa?How many moles of gaseous boron trifluoride, BF3, are contained in a 4.3410-L bulb at 788.0 K if the pressure is 1.220 atm? How many grams of BF3?Iodine, I2, is a solid at room temperature but sublimes (converts from a solid into a gas) when warmed. What is the temperature in a 73.3-mL bulb that contains 0.292 g of I2 vapor at a pressure of 0.462 atm?How many grams of gas are present in each of the following cases? (a) 0.100 L of CO2 at 307 torr and 26 C (b) 8.75 L of C2H4, at 378.3 kPa and 483 K (c) 221 mL of Ar at 0.23 torr and 54 C A high altitude balloon is filled with 1041104 L of hydrogen at a temperature of 21 C and a pressure of 745 torr. What is the volume of the balloon at a height of 20 km. where the temperature is 48 C and the pressure is 63.1 torr?A cylinder of medical oxygen has a volume of 3S.4 L. and contains O2 at a pressure of 1S1 atm and a temperature of 2S C. What volume of O2 does this correspond to at normal body conditions, that is. 1 atm and 37 C?A large scuba tank (Figure 9.16) with a volume of 18 L is rated for a pressure of 220 bar. The tank is filled at 20 °C and contains enough air to supply 1860 L of air to a diver at a pressure of 2.37 atm (a depth of -15 feet). Was the tank filled to capacity a 20 °C?A 20.0-L cylinder containing 11.34 kg of butane, C4H10, was opened to the atmosphere. Calculate the mass of the gas remaining in the cylinder if it were opened and the gas escaped until the pressure in the cylinder was equal to the atmospheric pressure. 0.983 atm, and a temperature of 27 C.While resting, the average 70-kg human male consumes 14 L of pure O2 per hour at 25 C and 100 kPa. How many moles of 02 are consumed by a 70 kg man while resting for 1.0 h?For a given amount of gas showing ideal behavior, draw labeled graphs of: (a) the variation of P with V (b) the variation of V with T (C) the variation of P with T (d) the variation of 1P with V A liter of methane gas, CH4, at STP contains more atoms of hydrogen than does a liter of pure hydrogen gas, H2, at STP. Using Avogadro’s law as a starting point, explain why.The effect of chlorofluorocarbons (such as CCl2F2) on the depletion of the ozone layer is well known. The use of substitutes, such as CH3CH2F(g), for the chlorofluorocarbons, has largely corrected the problem. Calculate the volume occupied by 10.0 g of each of these compounds at STP: (a) CCl2F2(g) (b) CH3CH2F(g)As 1 g of (lie radioactive element radium decays over 1 year. k produces 1.161018 alpha particles (helium nuclei). Each alpha particle becomes an atom of helium gas. What is the pressure ¡n pascal of the helium gas produced if it occupies a volume of 125 mL at a temperature of 25 C?A balloon that is 100.21 L at 21 C and 0.981 atm is released and just barely clears the top of Mount crumpet in British Columbia. If the final volume of the balloon is 144.53 L at a temperature of 5.24 C, what is the pressure experienced by the balloon as it clears Mount Crumpet?If the temperature of a fixed amount of a gas is doubled at constant volume, what happens to the pressure?If the volume of a fixed amount of a gas is tripled at constant temperature, what happens to the pressure?What is the density of laughing gas, dinitrogen monoxide, N2O, at a temperature of 325 K and a pressure of 113.0 kPa?Calculate the density of Freon 12, CF2Cl2, at 30.0 C and 0.954 atm.Which is denser at the same temperature and pressure, dry air or air saturated with water vapor? Explain.A cylinder of O2(g) used in breathing by emphysema patients has a volume of 3.00 L at a pressure of 10.0 atm. If the temperature of the cylinder is 28.0 C, what mass of oxygen is in the cylinder?What is the molar mass of a gas if 0.0494 g of the gas occupies a volume of 0.100 L at a temperature 26 C and a pressure of 307 torr?What is the molar mass of a gas if 0.281 g of the gas occupies a volume of 125 mL at a temperature 126 C and a pressure of 777 torr?How could you show experimentally that the molecular formula of propene is C3H6, not CH2?The density of a certain gaseous fluoride of phosphorus is 3.93 g/L at STP. Calculate the molar mass of this fluoride and determine its molecular formula.Consider this question: What is the molecular formula of a compound that contains 39% C. 45% N, and 16% H if 0.157 g of the compound occupies 125 mL with a pressure of 993 kPa at 22 C? (a) Outline the steps necessary to answer the question. (b) Answer the question.A 36.0—L cylinder of a gas used for calibration of blood gas analyzers in medical laboratories contains 350 g CO2, 805 g 02, and 4,880 g N2. At 25 degrees C. what is the pressure in the cylinder in atmospheres?A cylinder of a gas mixture used for calibration of blood gas analyzers in medical laboratories contains 5.0% CO2, 12.0% O2, and the remainder N2 at a total pressure of 146 atm. What is the partial pressure of each component of this gas? (The percentages given indicate the percent of the total pressure that is due to each component.)A sample of gas isolated from unrefined petroleum contains 90.0% CH4, 8.9% C2H6, and 1.1% C3H8 at a total pressure of 307.2 kPa. What is the partial pressure of each component of this gas? (The percentages given indicate the percent of the total pressure that is due to each component.)A mixture of 0.200 g of 1.00 g of and 0.820 g of Ar is stored in a closed container at STP. Find the volume of the container, assuming that the gases exhibit ideal behavior.Most mixtures of hydrogen gas with oxygen gas are explosive. However, a mixture that contains less than 3.0 % O2 is not. If enough O2 is added to a cylinder of H2 at 33.2 atm to bring the total pressure to 3-13 atm, is the mixture explosive?A commercial mercury vapor analyzer can detect in air, concentrations of gaseous Hg atoms (which are poisonous) as low as 2106 mg/L of air. At this concentration, what is the partial pressure of gaseous mercury if the atmospheric pressure is 733 tort at 26 C?A sample of carbon monoxide was collected over water at a total pressure of 756 torr and a temperature of 18 °C. What is the pressure of the carbon monoxide? (See Table 9.2 for the vapor pressure of water.)In an experiment in a general chemistry laboratory, a student collected a sample of a gas over water. The volume of the gas was 265 mL at a pressure of 753 torr and a temperature of 27 C. The mass of the gas was 0.472 g. What was the molar mass of the gas?Joseph Priestley first prepared pure oxygen by heating mercuric oxide, HgO: 2HgO(s)2Hg(l)+O2(g) (a) Outline the steps necessary to answer the following question: What volume of O2 at 23 C and 0.975 atm is produced by the decomposition of 5.36 g of HgO? (b) Answer the question.Cavendish prepared hydrogen in 176G by the novel method of passing steam through a red-hot gun barrel: 4H2O(g)+3Fe(s)3Fe3O4(s)+4H2(s) (a) Outline the steps necessary o answer the following question: What volume of H2 at a pressure of 743 torr and a temperature of 20 C can be prepared from the reaction of 13.0 g of H2O? (b) Answer the question.The chlorofluorocarbon CCl2F2 can be recycled into a different compound by reaction with hydrogen to produce CCl2F2(g), a compound useful in chemical manufacturing: CCl2F2(g)+4H2(g)CH2F2(g)+2HCl(g) (a) Outline the steps necessary to answer the following question: What volume of hydrogen at 225 atm and 35.5 C would be required to react with 1 ton (1.000103kg) of CCl2F2? (b) Answer the question.Automobile air bags are inflated with nitrogen gas, which is formed by the decomposition of solid sodium azide (NaN3). The other product is sodium metal. Calculate the volume of nitrogen gas at 27 C and 756 torr formed by the decomposition of 125 g of sodium azide.Lime, CaO, is produced by heating calcium carbonate, CaCO3 : carbon dioxide is the other product. (a) Outline the steps necessary to answer the following question: What volume of carbon dioxide a 875 K and 0966 atm is produced by the decomposition of 1 ton (1.000103kg) of calcium carbonate? (b) Answer the question.Before small batteries were available, carbide lamps were used for bicycle lights. Acetylene gas. C2H2, and solid calcium hydroxide were formed by the reaction of calcium carbide, CaC2. with water. The ignition of the acetylene gas provided the light. Currently, the same lamps are used by some cavers, and calcium carbide is used to produce acetylene for carbide cannons. (a) Outline the steps necessary to answer the following question: What volume of C2H2 at 1.005 atm and 12.2 C is formed by the reaction of 15.48 g of CaC2 with water? (b) Answer the question.Calculate the volume of oxygen required to burn 12.00 L of ethane gas, C2H6, to produce carbon dioxide and water, if the volumes of C2H6 and O2 are measured under the same conditions of temperature and pressure.What volume of O2 at STP is required to oxidize 8.0 L of NO at SW to NO2? What volume of NO2 is produced at SW?Consider the following questions: (a) What is the total volume of the CO2(g) and H2O(g) at 600 C and 0.888 atm produced by the combustion of 1.00 L of C2H6(g) measured at STP? (b) What is the partial pressure of H2O in the product gases?Methanol, CH3OH, is produced industrially by the following reaction: CO(g)+2H2(g)coppercatalyst300C,300atmCH3OH(g) Assuming that the gases behave as ideal gases, find the ratio of the total volume of the reactants to the final volume.What volume of oxygen a 423.0 K and a pressure of 127.4 kPa is produced by the decomposition of 129.7 g of BaO2 to BaO and O2?A 230-L sample of a colorless gas at STP decomposed to give 230 L of N2 and 1.25 L of O2 at STP. What is the colorless gas?Ethanol, C2H5OH, is produced industrially from ethylene, C2H4, by the following sequence of reactions: 3C2H4+2H2SO4C2H5HSO4+( C 2 H 5)2SO4C2H5HSO4+( C 2 H 5)2SO4+3H2O3C2H5OH+2H2SO4 What volume of ethylene at STP is required to produce 1.000 metric ton (1000 kg) of ethanol if the overall yield of ethanol is 90.1%?One molecule of hemoglobin will combine with four molecules of oxygen. If 1.0 g of hemoglobin combines with 133 mL of oxygen at body temperature (37 C) and a pressure of 743 tort, what is the molar mass of hemoglobin?A sample of a compound of xenon and fluorine was confined in a bulb with a pressure of 18 tor. Hydrogen was added to the bulb until the pressure was 72 torr. Passage of an electric spark through the mixture produced Xe and HF. After the HF was removed by reaction with solid KOH, the final pressure of xenon and unreacted hydrogen in the bulb was 36 torr. What is the empirical formula of the xenon fluoride in the original sample? (Note: Xenon fluorides contain only one xenon atom per molecule.)One method of analyzing amino acids is the van Slyke method. The characteristic amino groups (NH2) in protein material are allowed to react with nitrous acid. HNO2, to form N2 gas. From the volume of the gas, the amount of amino acid can be determined. A 0.0604-g sample of a biological sample containing glycine, CH2(NH2)COOH, was analyzed by the van Slyke method and yielded 3.70 mL of N2 collected over water at a pressure of 735 torr and 29 C. What was the percentage of glycine in the sample? CH2(NH2)CO2H+HNO2CH2(OH)CO2H+H2O+N2 A balloon filled with helium gas is found to take 6 hours to deflate to 50% of its original volume. How long will it take for an identical balloon filled with the same volume of hydrogen gas (instead of helium) to decrease its volume by 50%?Explain why the numbers of molecules are not identical in the left- and tight-hand bulbs shown in the center illustration of Figure 9.27.Starting with the definition of rate of effusion and Graham’s finding relating rate and molar mass, show how to derive the Graham’s law equation, relating the relative rates of effusion for two gases to their molecular masses.Heavy water, D2O (molar mass = 20.03 g mol-1). can be separated from ordinary water, H2O (molar mass = 18.01), as a result of the difference in the relative rates of diffusion of the molecules in the gas phase. Calculate the relative rates of diffusion of H2O and D2O.Which of the following gases diffuse more slowly than oxygen? F2,Ne,N2O,C2H2,NO,Cl2,H2S During the discussion of gaseous diffusion for enriching uranium, it was claimed that 235UF6 diffuses 0.4% faster than 238UF6. Show the calculation that supports this value. The molar mass of 235UF6=235.043930+618.998403=349.034348 g/mol, and the molar mass of 238UF6=238.050788+618.998403=352.241206 g/mol.Calculate the relative rate of diffusion of 1H2 (molar mass 2.0 gmol) compared to that of 2H2 (molar mass 4.0 g/mol) and the relative rate of diffusion of O2 (molar mass 32 g/mol) compared to that of O3 (molar mass 48 g/mol).A gas of unknown identity diffuses at a rate of 83.3 mL/s in a diffusion apparatus in which carbon dioxide diffuses at the rate of 102 mL/s. Calculate the molecular mass of the unknown gas.When two cotton plugs. one moistened with ammonia and the other with hydrochloric acid, are simultaneously inserted into opposite ends of a glass tube that is 87.0 cm long, a white 1111g of NH4Cl forms where gaseous NH3 and gaseous HC1 first come into contact. NH3(g)+HCl(g)NH4Cl(s) At approximately what distance from the ammonia moistened plug does this occur? (Hint: Calculate the rates of diffusion for both NH3 and HCI, and find out how much faster NH3 diffuses than HCI.)Using the postulates of the kinetic molecular theory, explain why a gas uniformly fills a container of any shape.Can the speed of a given molecule in a gas double at constant temperature? Explain your answer.Describe what happens o the average kinetic energy of ideal gas molecules when the conditions are changed as follows: (a) The pressure of the gas is increased by reducing the volume at constant temperature. (b) The pressure of the gas is increased by increasing the temperature at constant volume. (c) The average velocity of the molecules is increased by a factor of 2.The distribution of molecular velocities in a sample of helium is shown in Figure 9.34. If the sample is cooled, will the distribution of velocities look more like that of H2 or of H2O? Explain your answer.What is the ratio of the average kinetic energy of a SO2 molecule to that of an O2 molecule in a mixture of two gases? What is the ratio of the root mean square speeds, urms, of the two gases?A 1-L sample of CO initially at STP is heated to 546 K. and its volume is increased to 2 L. (a) What effect do these changes have on the number of collisions of the molecules of the gas per unit area of the container wall? (b) What is the effect on the average kinetic energy of the molecules? (c) What is the effect on the root mean square speed of the molecules?The root mean square speed of H2, molecules at 25 C is about 1.6 km/s. What is the root mean square speed of a N2, molecule at 25 C?Answer the following questions: (a) Is the pressure of the gas in the hot air balloon shown at the opening of this chapter greater than, less than, or equal to that of the atmosphere outside the balloon? (b) Is the density of the gas in the hot air balloon shown at the opening of this chapter greater than, less than, or equal to that of the atmosphere outside the balloon? (c) At a pressure of 1 atm and a temperature of 20 C, dry air has a density of 1.2256 gt. What is the (average) molar mass of div air? (d) The average temperature of the gas in a hot air balloon is 1.30102 F. Calculate its density, assuming the molar mass equals that of div air. (e) The lifting capacity of a hot air balloon is equal to the difference in the mass of the cool air displaced by the balloon and the mass of the gas in the balloon. What is the difference in the mass of 1.00 L of the cool air in part (c) and the hot air in part (d)? (f) An average balloon has a diameter of 60 feet and a volume of 1.1105ft3. What is the lifting power of such a balloon? If the weight of the balloon and its rigging is 500 pounds, what is its capacity for carrying passengers and cargo? (g) A balloon carries 40.0 gallons of liquid propane (density 0.5005 g/L). What volume of CO2 and H2O gas is produced by the combustion of this propane? (h) A balloon flight can last about 90 minutes. If all of the fuel is burned during this time, what is the approximate rate of heat loss (in kJ/min) from the hot air in the bag during the flight?Show that the ratio of the rate of diffusion of Gas 1 to the rate of diffusion of Gas 2, R1R2, is the same at 0 C and 100C.Graphs showing the behavior of several different gases follow. Which of these gases exhibit behavior significantly different from that expected for ideal gases?Explain why the plot of PV for CO2 differs from that of an ideal gas.Under which of the following sets of conditions does a real gas behave most like an ideal gas, and for which conditions is a real gas expected to deviate from ideal behavior? Explain. (a) high pressure, small volume (b) high temperature, low pressure (c) low temperature, high pressure Describe the factors responsible for the deviation of the behavior of real gases from that of an ideal gas.For which of the following gases should the correction for the molecular volume be largest: CO,CO2,H2,He,NH3,SF6?A 0.245-L flask contains 0.467 mol CO2 at 159 C. Calculate the pressure: (a) using the ideal gas law (b) using the van der Waals equation (c) Explain the reason for the difference. (d) Identify which correction (that for P or V) is dominant and why.Answer the following questions: (a) If XX behaved as an ideal gas, what would its graph of Z vs. P look like? (b) For most of this chapter, we performed calculations treating gases as ideal. Was this justified? (c) What is the effect of the volume of gas molecules on Z? Under what conditions is this effect small? When is it large? Explain using an appropriate diagram. (d) What is the effect of intermolecular attractions on the value of Z? Under what conditions is this effect small? When is it large? Explain using an appropriate diagram. (e) In general, under what temperature conditions would you expect Z to have the largest deviations from the Z for an ideal gas?In terms of their bulk properties, how do liquids and solids differ? How are they similar?In terms of the kinetic molecular theory, in what ways are liquids similar to solids? In what ways are liquids different from solids?In terms of the kinetic molecular theory, in what ways are liquids similar to gases? In what ways are liquids different from gases?Explain why liquids assume the shape of any container into which they are poured, whereas solids are rigid and retain their shape.What is the evidence that all neutral atoms and molecules exert attractive forces on each other?Open the PhET States of Matter Simulation (http://openstaxcollege.org/l/16phetvisual) to answer the following questions: (a) Select the Solid, Liquid, Gas tab. Explore by selecting different substances, heating and cooling the systems, and changing the state. What similarities do you notice between the four substances for each phase (solid, liquid, gas)? What differences do you notice? (b) For each substance, select each of the states and record the given temperatures. How do the given temperatures for each state correlate with the strengths of their intermolecular attractions? Explain. (c) Select the Interaction Potential tab, and use the default neon atoms. Move the Ne atom on the right and observe how the potential energy changes. Select the Total Force button, and move the Ne atom as before. When is the total force on each atom attractive and large enough to matter’? Then select the Component Forces button, and move the Ne atom. When do the attractive (van der Waals) and repulsive (electron overlap) forces balance? How does this relate to the potential energy versus the distance between atoms graph? Explain.Define the following and give an example of each: (a) dispersion force (b) dipole-dipole attraction (c) hydrogen bond The types of intermolecular forces in a substance are identical whether it is a solid, a liquid, or a gas. Why then does a substance change phase from a gas to a liquid or to a solid?Why do the boiling points of the noble gases increase in the order HeNeArKrXe?Neon and HF have approximately the same molecular masses. (a) Explain why the boiling points of Neon and HF differ. (b) Compare the change in the boiling points of Ne, Ar, Kr, and Xe with the change of the boiling points of HF, HCl, HBr, and HI, and explain the difference between the changes with increasing atomic or molecular mass.Arrange each of the following sets of compounds in order of increasing boiling point temperature: (a) HCl,H2O,SiH4 (b) F2,Cl2,Be2 (c) CH4,C2H6,C3H8 (d) O2,NO,N2 The molecular mass of butanol, C4H9OH, is 74.14; that of ethylene glycol, CH2(OH)CH2OH, is 62.08, yet their boiling points are 117.2 C and 174 C, respectively. Explain the reason for the difference.On the basis of intermolecular attractions, explain the differences in the boiling points of n butane (1 C) and chloroethane (12 C), which have similar molar masses.On the basis of dipole moments and/or hydrogen bonding, explain in a qualitative way the differences in the boiling points of acetone (56.2 C) and 1propanol (97.4 C), which have similar molar masses.The melting point of H2O(s) is O C. Would you expect the melting point of H2S(s) to be 85 C, O C, or 185 C? Explain your answer.Silane SiH4, phosphine (PH3), and hydrogen sulfide (H2S) melt at 185 C, 133 C, and 85 C, respectively. What does this suggest about the polar character and intermolecular attractions of the three compounds?Explain why a hydrogen bond between two water molecules is weaker than a hydrogen bond between two hydrogen fluoride molecules.Under certain conditions, molecules of acetic acid, CH3COOH, form dimers, pairs of acetic acid molecules held together by strong intermolecular attractions: Draw a dimer of acetic acid, showing how two CH3COOH molecules are held together, and stating the type of ¡MF that is responsible.Proteins are chains of amino acids that can form in a variety of arrangements, one of which is a helix. What kind of IMF is responsible for holding the protein strand in this shape? On the protein image, show the locations of the ¡MFs that hold the protein together:The density of liquid NH3 is 0.64 g/mL; the density of gaseous NH3 at STP is 0.0007 g/mL. Explain the difference between the densities of these two phases.Identify the intermolecular forces present in the following solids: (a) CH3CH2OH (b) CH3CH2CH3 (c) CH3CH2Cl The test tubes shown here contain equal amounts of the specified motor oils. Identical metal spheres were dropped at the same time into each of the tubes, and a brief moment later, the spheres had fallen to the heights indicated in the illustration. Rank the motor oils in order of increasing viscosity, and explain your reasoning:Although steel is denser than water, a steel needle or paper clip placed carefully lengthwise on the surface of still water can be made to float. Explain at a molecular level how this is possible: Figure 10.67 (credit: Cory Zanker)The surface tension and viscosity values for diethyl ether, acetone, ethanol, and ethylene glycol are shown here. (a) Explain their differences in viscosity in items of the size and shape of their molecules and their IMFs. (b) Explain their differences in surface tension in items of the size and shape of their molecules and their IMFs:You may have heard someone use the figure of speech slower than molasses in winter to describe a process that occurs slowly. Explain why this is an apt idiom, using concepts of molecular size and shape, molecular interactions, and the effect of changing temperature.It is often recommended that you let your car engine run idle to warm up before driving, especially on cold winter days. While the benefit of prolonged idling is dubious, it is certainly true that a warm engine is more fuel efficient than a cold one. Explain the reason for this.The surface tension and viscosity of water at several different temperatures are given in this table. Water Surface Tension (mN/m) Viscosity (mPa s) 0 C 75.6 1.79 20 C 72.8 1.00 60 C 66.2 0.47 100 C 58.9 0.28 (a) As temperature increases, what happens to the surface tension of water? Explain why this occurs, in terms of molecular interactions and the effect of changing temperature. (b) As temperature increases, what happens to the viscosity of water? Explain why this occurs, in terms of molecular interactions and the effect of changing temperature.At 25 C, how high will water rise in a glass capillary tube with an inner diameter of 0.63 mm? Refer to Example 10.4 for the required information.Water rises in a glass capillary tube to a height of 17 cm. What is the diameter of the capillary tube?Heat is added to boiling water. Explain why the temperature of the boiling water does not change. What does change?Heat is added to ice at 0 C. Explain why the temperature of the ice does not change. What does change?What feature characterizes the dynamic equilibrium between a liquid and its vapor in a closed container?Identify two common observations indicating some liquids have sufficient vapor pressures to noticeably evaporate?Identify two common observations indicating some solids, such as dry ice and mothballs, have vapor pressures sufficient to sublime?What is the relationship between the intermolecular forces in a liquid and its vapor pressure?What is the relationship between the intermolecular forces in a solid and its melting temperature?Why does spilled gasoline evaporate more rapidly on a hot day than on a cold day?Carbon tetrachloride, CCl4, was once used as a dry cleaning solvent, but is no longer used because it is carcinogenic. At 57.8 C, the vapor pressure of CCl4 is 54.0 kPa, and its enthalpy of vaporization is 33.05 kJ/mol. Use this information to estimate the normal boiling point for CC14.When is the boiling point of a liquid equal to its normal boiling point?How does the boiling of a liquid differ from its evaporation?Use the information in Figure 10.24 to estimate the boiling point of water in Denver when the atmospheric pressure is 83.3 kPa.A syringe at a temperature of 20 C is filled with liquid ether in such a way that there is no space for any vapor. If the temperature is kept constant and the plunger is withdrawn to create a volume that can be occupied by vapor, what would be the approximate pressure of the vapor produced?Explain the following observations: (a) It takes longer to cook an egg in Ft. Davis, Texas (altitude, 5000 feet above sea level) than it does in Boston (at sea level). (b) Perspiring is a mechanism for cooling the body.The enthalpy of vaporization of water is larger than its enthalpy of fusion. Explain why.Explain why the molar enthalpies of vaporization of the following substances increase in the order CH4C2H6C3H8, even though the type of IMF (dispersion) is the same.Explain why the enthalpies of vaporization of the following substances increase in the order CH4NH3H2O, even though all three substances have approximately the same molar mass.The enthalpy of vaporization of CO2(l) is 9.8 kJ/mol. Would you expect the enthalpy of vaporization of CS2(l) to be 28 kJ/mol, 9.8 kJ/mol, or 8.4 kJ/mol? Discuss the plausibility of each of these answers.The hydrogen fluoride molecule, HF, is more polar than a water molecule, H2O (for example, has a greater dipole moment), yet the molar enthalpy of vaporization for liquid hydrogen fluoride is lesser than that for water. Explain.Ethyl chloride (boiling point, 13 C) is used as a local anesthetic. When the liquid is sprayed on the skin, it cools the skin enough to freeze and numb it. Explain the cooling effect of liquid ethyl chloride.Which contains the compounds listed correctly in order of increasing boiling points? (a) N2CS2H2OKCl (b) H2ON2CS2KCl (c) N2KClCS2H2O (d) CS2N2KClH2O (e) KClH2OCS2N2 How much heat is required to convert 422 g of liquid H2O at 23.5 C into steam at 150 C?Evaporation of sweat requires energy and thus take excess heat away from the body. Some of the water that you drink may eventually be converted into sweat and evaporate. If you drink a 20-ounce bottle of water that had been in the refrigerator at 3.8 C, how much heat is needed to convert all of that water into sweat and then to vapor? (Note: Your body temperature is 36.6 oc. For the purpose of solving this problem, assume that the thermal properties of sweat are the same as for water.)Titanium tetrachloride, TiCl4, has a melting point of 23.2 C and has a Hfusion=9.37 kJ/mol. (a) How much energy is required to melt 263.1 g TiCl4? (b) For TiCl4, which will likely have the larger magnitude: Hfusion or Hvaporization? Explain your reasoning.From the phase diagram for water (Figure 10.31), determine the state of water at: (a) 35 °C and 85 kPa (b) 15 °C and 40 kPa (c) is °C and 0.1 kPa (d) 75 °C and 3 kPa (e) 40 °C and 0.1 kPa (f) 60 °C and 50 kPa What phase changes will take place when water is subjected to varying pressure at a constant temperature of 0.005 C? At 40 C? At 40 C?Pressure cookers allow food to cook faster because the higher pressure inside the pressure cooker increases the boiling temperature of water. A particular pressure cooker has a safety valve that is set to vent steam if the pressure exceeds 3.4 atm. What is the approximate maximum temperature that can be reached inside this pressure cooker? Explain your reasoning.From the phase diagram for carbon dioxide in Figure 10.34, determine the state of CO2 at: (a) 20 °C and 1000 kPa (b) 10 °C and 2000 kPa (c) 10 °C and loo kPa (d) 40 °C and 500 kPa (e) 80 °C and 1500 kPa (f) 80 °C and 10 kPa Determine the phase changes that carbon dioxide undergoes as the pressure changes if (lie temperature is held at 50 °C? If the temperature is held at 40 °C? At 20 °C? (See the phase diagram in Figure 10.34.)Consider a cylinder containing a mixture of liquid carbon dioxide in equilibrium with gaseous carbon dioxide at an initial pressure of 65 atm and a temperature of 20 C. Sketch a plot depicting the change in the cylinder pressure with time as gaseous carbon dioxide is released at constant temperature.Dry ice, CO2(s) , does not melt at atmospheric pressure. It sublimes at a temperature of 78 °C. What is the lowest pressure at which CO2(s) will melt to give CO2(l) ? At approximately what temperature will this occur? (See Figure 10.34 for the phase diagram.)If a severe storm results in the loss of electricity, it may be necessary to use a clothesline to dry laundry. In many parts of the country in the dead of winter, the clothes will quickly freeze when they are hung on the line. If it does not snow, will they dry anyway? Explain your answer.Is it possible to liquefy nitrogen at room temperature (about 25 C)? Is it possible to liquefy sulfur dioxide at room temperature? Explain your answers.Elemental carbon has one gas phase, one liquid phase, and two different solid phases, as shown in the phase diagram: (a) On the phase diagram, label the gas and liquid regions. (b) Graphite is the most stable phase of carbon at normal conditions. On the phase diagram, label the graphite phase. (c) If graphite at normal conditions is heated to 2500 K while the pressure is increased to 1010 Pa, it is converted into diamond. Label the diamond phase. (d) Circle each triple point on the phase diagram. (e) In what phase does carbon exist at 5000 K and 108 Pa? (f) If the temperature of a sample of carbon increases from 3000 K to 5000 K at a constant pressure of 106 Pa, which phase transition occurs, if any?What types of liquids typically form amorphous solids?At very low temperatures oxygen, O2, freezes and forms a crystalline solid. Which best describes these crystals? (a) ionic (b) covalent network (c) metallic (d) amorphous (e) molecular crystals As it cools, olive oil slowly solidifies and forms a solid over a range of temperatures. Which best describes the solid? (a) ionic (b) covalent network (c) metallic (d) amorphous (e) molecular crystals Explain why ice, which is a crystalline solid, has a melting temperature of 0C, whereas butter, which is an amorphous solid, softens over a range of temperatures.Identify the type of crystalline solid (metallic, network covalent, ionic, or molecular) formed by each of the following substances: (a) SiO2 (b) KCl (c)Cu (d) CO2 (e) C (diamond) (f) BaSO4 (g) NH3 (h) NH4F (j) C2H5OH Identify the type of crystalline solid (metallic, network covalent, ionic, or molecular) formed by each of the following substances: (a) CaCl2 (b) SiC (c) N2 (d) Fe (e) C (graphite) (f) CH3CH2CH2CH3 (g) HCl (h) NH4NO3 (j) K3PO4 Classify each substance in the table as either a metallic, ionic, molecular, or covalent network solid: Substance Appearance Melting Point Electrical Conductivity Solubility in Water X lustrous, malleable 1500 C high insoluble Y Soft, yellow 113 C None Insoluble Z Hard, white 800 C Only if melted/dissolved soluble Classify each substance in the table as either a metallic, ionic, molecular, or covalent network solid: Substance Appearance Melting Point Electrical Conductivity Solubility in Water X brittle, white 800 C only if melted/dissolved soluble Y shiny, malleable 1100 C high insoluble X hard, colorless 3550 C none insoluble Identify the following substances as ionic, metallic, covalent network, or molecular solids: Substance A is malleable, ductile, conducts electricity well, and has a melting point of 1135 C. Substance B is brittle, does not conduct electricity as a solid but does when molten, and has a melting point of 2072 C. Substance C is very hard, does not conduct electricity, and has a melting point of 3440 C. Substance D is soft, does not conduct electricity, and has a melting point of 18S C.Substance A is shiny, conducts electricity well, and melts at 975 C. Substance A is likely a(n): (a) ionic solid (b) metallic solid (c) molecular solid (d) covalent network solid Substance B is hard, does not conduct electricity, and melts at 1200 C. Substance B is likely a(n): (a) ionic solid (b) metallic solid (c) molecular solid (d) covalent network solid Describe the crystal structure of iron, which crystallizes with two equivalent metal atoms in a cubic unit cell.Describe the crystal structure of Pt, which crystallizes with four equivalent metal atoms in a cubic unit cell.What is the coordination number of a chromium atom in the body-centered cubic structure of chromium?What is the coordination number of an aluminum atom in the facecentered cubic structure of aluminum?Cobalt metal crystallizes in a hexagonal closest packed structure. What is the coordination number of a cobalt atom?Nickel metal crystallizes in a cubic closest packed structure. What is the coordination number of a nickel atom?Tungsten crystallizes in a body-centered cubic unit cell with an edge length of 3.165 . (a) What is the atomic radius of tungsten in this structure? (b) Calculate the density of tungsten.Platinum (atomic radius =1.38) crystallizes in a cubic closely packed structure. Calculate the edge length of the facecentered cubic unit cell and the density of platinum.Barium crystallizes in a body-centered cubic unit cell with an edge length of 3.025 (a) What is the atomic radius of barium in this structure? (b) Calculate the density of barium.Aluminum (atomic radius = 1.43 ) crystallizes in a cubic closely packed structure. Calculate the edge length of the face—centered cubic unit cell and the density of aluminum.The density of aluminum is 2.7 g/cm3; that of silicon is 2.3 g/cm3. Explain why Si has the lower density even though it has heavier atoms.The free space in a metal may be found by subtracting the volume of the atoms in a unit cell from the volume of the cell. Calculate the percentage of free space in each of the three cubic lattices if all atoms in each are of equal size and touch their nearest neighbors. Which of these structures represents the most efficient packing? That is, which packs with the least amount of unused space?Cadmium sulfide, sometimes used as a yellow pigment by artists, crystallizes with cadmium, occupying one half of the tetrahedral holes in a closest packed array of sulfide ions. What is the formula of cadmium sulfide? Explain your answer.A compound of cadmium, tin, and phosphorus is used in the fabrication of some semiconductors. It crystallizes with cadmium occupying one-fourth of the tetrahedral holes and tin occupying one-fourth of the tetrahedral holes in a closest packed array of phosphide ions. What is the formula of the compound? Explain your answer.What is the formula of the magnetic oxide of cobalt, used in recording tapes, that crystallizes with cobalt atoms occupying one-eighth of the tetrahedral holes and one-half of the octahedral holes in a closely packed array of oxide ions?A compound containing zinc, aluminum, and sulfur crystallizes with a closest-packed array of sulfide ions. Zinc ions are found in one-eighth of the tetrahedral holes and aluminum ions in one-half of the octahedral holes. What is the empirical formula of the compound?A compound of thallium and iodine crystallizes in a simple cubic array of iodide ions with thallium ions in all of the cubic holes. What is the formula of this iodide? Explain your answer.Which of the following elements reacts with sulfur to form a solid in which the sulfur atoms form a closest packed array with all of the octahedral holes occupied: Li, Na, Be, Ca, or Al?What is the percent by mass of titanium in rutile, a mineral that contains titanium and oxygen, if structure can be described as a closest packed array of oxide ions with titanium ions in one-half of the octahedral holes? What is the oxidation number of titanium?Explain why the chemically similar alkali metal chlorides NaCl and CsCl have different structures, whereas the chemically different NaCl and MnS have the same structure.As minerals were formed from the molten magma, different ions occupied the same cites in the crystals. Lithium often occurs along with magnesium in minerals despite the difference in the charge on their ions. Suggest an explanation.Rubidium iodide crystallizes with a cubic unit cell that contains iodide ions at the corners and a rubidium ion in the center. What is the formula of the compound?One of the various manganese oxides crystallizes with a cubic unit cell that contains manganese ions at the corners and in the center. Oxide ions are located at the center of each edge of the unit cell. What is the formula of the compound?NaH crystallizes with the same ciystal structure as NaCl. The edge length of the cubic unit cell of NaH is 4.880. (a) Calculate the ionic radius of H. (The ionic radius of Li+ is 0.0.95 .) (b) Calculate the density of NaH.Thallium(I) iodide crystallizes with the same structure a CsCl. The edge length of the Unit cell of TlI is 4.20. Calculate the ionic radius of TI+. (The ionic radius of I is 2.16 .)A cubic unit cell contains manganese ions at the corners and fluoride ions at the center of each edge. (a) What is the empirical formula of this compound? Explain your answer. (b) What is the coordination number of the Mn3+ ion? (c) Calculate the edge length of the unit cell if the radius of a Mn3+ ion is 0.65 A. (d) Calculate the density of the compound.What is the spacing between crystal planes that diffract X-rays with a wavelength of 1.541 nm at an angle of 15.55 (first order reflection)?A diffracrometer using X-rays with a wavelength of 0.2287 nm produced first-order diffraction peak for a crystal angle =16.21. Determine the spacing between the diffracting planes in this crystal.A metal with spacing between planes equal to 0.4164 nm diffracts X-rays with a wavelength of 0.2879 nm. What is the diffraction angle for the first order diffraction peak?Gold crystallizes in a face-centered cubic unit cell. The second-order reflection ( n=2) of X-rays for the planes that make up the tops and bottoms of the unit cells is at =22.20. The wavelength of the X-rays is 1.54 A. What is the density of metallic gold?When an electron in an excited molybdenum atom falls from the L to the K shell, an X-ray is emitted. These X-rays are diffracted at an angle of 7.75 by planes with a separation of 2.64 A. What is the difference iii energy between the K shell and the L shell in molybdenum assuming a first-order diffraction?How do solutions differ from compounds? From other mixtures?Which of the principal characteristics of solutions can we see in the solutions of K2Cr2O7 shown in Figure 11.2?When KNO3 is dissolved in water, the resulting solution is significantly colder than the water was originally. (a) Is the dissolution of KNO3 an endothermic or an exothermic process? (b) What conclusions can you draw about the intermolecular attractions involved in the process? (c) Is the resulting solution an ideal solution?Give an example of each of the following types of solutions: (a) a gas in a liquid (b) a gas in a gas (c) a solid in a solid Indicate the most important types of intermolecular attractions in each of the following solutions: (a) The solution in Figure 11.2. (b) NO(I) in CO(I) (c) CI2(g) in Br2(l) (d) HCl(g) in benzene C6H6(l) (e) Methanol CH3OH(I) in H2O(I)Predict whether each of the following substances would be more soluble in water (polar solvent) or in a hydrocarbon such as heptane (C7H16, nonpolar solvent): (a) vegetable oil (nonpolar) (b) isopropyl alcohol (polar) (c) potassium bromide (ionic)Heat is released when some solutions form; heat is absorbed when other solutions form. Provide a molecular explanation for the difference between these two types of spontaneous processes.Solutions of hydrogen in palladium may be formed by exposing Pd metal to H2 gas. The concentration of hydrogen in the palladium depends on the pressure of H2 gas applied, but in a more complex fashion than can be described by Henry's law. Under certain conditions, 0.94 g of hydrogen gas is dissolved in 215 g of palladium metal (solution density = 10.8 g cm3). (a) Determine the molarity of this solution. (b) Determine the molality of this solution. (c) Determine the percent by mass of hydrogen atoms in this solution.Explain why the ions Na+ and CI- are strongly solvated in water but not in hexane, a solvent composed of nonpolar molecules.Explain why solutions of HBr in benzene (a nonpolar solvent) are nonconductive, while solutions in water (a polar solvent) are conductive.Consider the solutions presented: (a) Which of the following sketches best represents the ions in a solution of Fe(NO3)3(aq)? (b) Write a balanced chemical equation showing the p10ducts of the dissolution of Fe(NO3)3.Compare the processes that occur when methanol (CH3OH), hydrogen chloride (HCI), and sodium hydroxide (NaOH) dissolve in water. Write equations and prepare sketches showing the form in which each of these compounds is present in its respective solution.What is the expected electrical conductivity of the following solutions? (a) NaOH(aq) (b) HCI(aq) (c) C6H12O6(aq) (glucose) (d) NH3(aq)Why are most solid ionic compounds electrically nonconductive, whereas aqueous solutions of ionic compounds are good conductors? Would you expect a liquid (molten) ionic compound to be electrically conductive or nonconductive? Explain.Indicate the most important type of intermolecular attraction responsible for solvation in each of the following solutions: (a) the solutions in Figure 11.8 (b) methanol, CH3OH, dissolved in ethanol, C2H5OH (c) methane, CH4, dissolved in benzene, C6H6 (d) the polar halocarbon CF2CI2 dissolved in the polar halocarbon CF2CICFCI2 (e) O2(I) in N2(l)Suppose you are presented with a clear solution of sodium thiosulfate, Na2S2O3. How could you determine whether the solution is unsaturated, saturated, or supersaturated?Supersaturated solutions of most solids in water are prepared by cooling saturated solutions. Supersaturated solutions of most gases in water are prepared by heating saturated solutions. Explain the reasons for the difference in the two procedures.

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