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All Textbook Solutions for Chemistry & Chemical Reactivity

Answer (he following questions about the elements with the electron configurations shown here: A = [Ar]4s2 B =[Ar]3d104s24p5 (a) Is element A a metal, metalloid, or nonmetal? (b) Is element B a metal, metalloid, or nonmetal? (c) Which element is expected to have the larger ionization energy? (d) Which element has the smaller atomic radius?Which of the following ions are unlikely to be found in a chemical compound: Cs+, ln4+, Fe6+, Te2, Sn5+, and I? Explain briefly.56GQ Answer each of the following questions: (a) Of the elements S, Se, and Cl, which has the largest atomic radius? (b) Which has the larger radius, Br or Br? (c) Which should have the largest difference between the first and second ionization energy: Si, Na, P, or Mg? (d) Which has the largest ionization energy: N, P, or As? (e) Which of the following has the largest radius: O2, N3, or F?58GQ 59GQ Two elements in the second transition series (Y through Cd) have four unpaired electrons in their 3+ ions. What elements fit this description?61GQ The configuration of an element is given here. (a) What is the identity of the element? (b) In what group and period is the element found? (c) Is the element a nonmetal, a main group element, a transition metal, a lanthanide, or an actinide? (d) Is the element diamagnetic or paramagnetic? If paramagnetic, how many unpaired electrons are there? (e) Write a complete set of quantum numbers (n, , m, ms) for each of the valence electrons. (f) What is the configuration of the 2+ ion formed from this element? Is the ion diamagnetic or paramagnetic?Answer the questions below about the elements A and B, which have the ground state electron configurations shown. A = [kr]5s2 B =[kr]4d105s25p5 (a) Is element A a metal, nonmetal, or metalloid? (b) Which element has the greater ionization energy? (c) Which element has a larger atomic radius? (d) Which element has the more negative electron attachment enthalpy? (e) Which is more likely to form a cation? (f) What is a likely formula for a compound formed between A and B?Answer the questions below concerning ground state electron configurations. (a) What element has the electron configuration [Ar]3d64s2? (b) What element has a 2+ ion with the configuration [Ar]3d5? Is the ion paramagnetic or diamagnetic? (c) Mow many unpaired electrons are in a Ni2+ ion? (d) The configuration for an element is given here. What is the identity of the element? Is a sample of the element paramagnetic or diamagnetic? How many unpaired electrons does a 3 ion of this element have? (e) What element has the following electron configuration? Write a complete set of quantum numbers for electrons 1-3.Nickel(II) formate [Ni(HCO2)2] is widely used as a catalyst precursor and to make metallic nickel. It can be prepared in the general chemistry laboratory by treating nickel(II) acetate with formic acid (HCO2H). Ni(CH3CO2)2(aq) + 2 HCO2H(aq) Ni(HCO2)2(aq) + 2 CH3CO2H(aq) Green crystalline Ni(HCO2)2 is precipitated after adding ethanol to the solution. (a) What is the theoretical yield of nickel(II) formate from 0.500 g of nickel(II) acetate and excess formic acid? (b) Is nickel(II) formate paramagnetic or diamagnetic? If it is paramagnetic, how many unpaired electrons would you expect? (c) If nickel(II) formate is heated to 300 C in the absence of air for 30 minutes, the salt decomposes to form pure nickel powder. What mass of nickel powder should be produced by heating 253 mg of nickel(II) formate? Are nickel atoms paramagnetic?Spinets are solids with the general formula M2+ (M3+)2O4 (where M2+ and M3+ are metal cations of the same or different metals). The best-known example is common magnetite, Fe3O4 [which you can formulate as (Fe2+)(Fe3+)2O4]. A crystal of a spinet (a) Given its name, it is evident that magnetite is ferromagnetic. How many unpaired electrons are in iron(II) and in iron(III) ions? (b) Two other spinets are CoAl2O4 and SnCo2O4. What metal ions are involved in each? What are their electron configurations? Are the metal ions paramagnetic, and if so, how many unpaired electrons are involved?The following questions use concepts from this and previous chapters. Why is the radius of Li+ so much smaller than the radius of Li? Why is the radius of F so much larger than the radius of F?Which ions in the following list are not likely to be found in chemical compounds: K2+, Cs+, Al4+, F2, and S2+? Explain briefly.Answer the following questions about first ionization energies. (a) Generally ionization energies increase on proceeding across a period, but this is not true for magnesium (738 kJ/mol) and aluminium (578 kJ/mol). Explain this observation. (b) Explain why the ionization energy of phosphorus (1012 kJ/mol) is greater than that of sulphur (1000 kJ/mol) when the general trend in ionization energies in a period would predict the opposite.The ionization of the hydrogen atom can be calculated from Bohr's equation for the electron energy. E = (NARhc)(Z2/n2) where NARhc =1312 kJ/mol and Z is the atomic number. Let us use this approach to calculate a possible ionization energy for helium. First, assume the electrons of the He experience the full 2+ nuclear charge. This gives us the upper limit for the ionization energy. Next, assume one electron of He completely screens the nuclear charge from the other electrons, so Z = 1. This gives us a lower limit to the ionization energy. Compare these calculated values for the upper and lower limits to the experimental value of 2372.3 kJ/mol. What does this tell us about the ability of one electron to screen the nuclear charge?Compare the configurations below with two electrons located in p orbitals. Which would be the most stable (have the lowest energy)? Which would be the least stable? Explain your answers.72SCQ Write electron configurations to show the first two ionization processes for potassium. Explain why the second ionization energy is much greater than the first.74SCQ (a) Explain why the sizes of atoms change when proceeding across a period of the periodic table. (b) Explain why the sizes of transition metal atoms change very little across a period.Which of the following elements has the greatest difference between its first and second ionization energies: C, Li, N, Be? Explain your answer.77SCQ 78SCQ The energies of the orbitals in many elements have been determined. For the first two periods they have the following values: (a) Why do the orbital energies generally become more negative on proceeding across the second period? (b) How are these values related to the ionization energy and electron attachment enthalpy of the elements? (c) Use these energy values to explain the observation that the ionization energies of the first four second-period elements are in the order Li Be B C. (Data from J. B. Mann, T. L Meek, and L C. Allen: Journal of the American Chemical Society, Vol. 122, p. 2780. 2000.)The ionization energies for the removal of the first electron in Si, P, S. and CI are as listed in the table below. Briefly rationalize this trend.Using your knowledge of the trends in element sizes on going across the periodic table, explain briefly why the density of the elements increases from K through V.82SCQ 83SCQ 84SCQ Thionyl chloride. SOCl2, is an important chlorinating and oxidizing agent in organic chemistry. It is prepared industrially by oxygen atom transfer from SO3 to SC12. SO3(g) + SCl2(g) SO2(g) + SOCl2,(g) (a) Give the electron configuration for an atom of sulfur using an orbital box diagram. Do not use the noble gas notation. (b) Using the configuration given in part (a), write a set of quantum numbers for the highest- energy electron in a sulfur atom. (c) What element involved in this reaction (O, S, CI) should have the smallest ionization energy? The smallest radius? (d) Which should be smaller: the sulfide ion, S2, or a sulfur atom, S? (e) If you want to make 675 g of SOCl2, what mass of SCI2 is required? (f) If you use 10.0 g of SO3 and 10.0 g of SCl2, what is the theoretical yield of SOCl2? (g) rH for the reaction of SO3 and SCl2 is -96.0 kl/mol SOCl2 produced. Using data in Appendix L, calculate the standard molar enthalpy of formation of SCl2.86SCQ Slaters rules are a way to estimate the effective nuclear charge experienced by an electron. In this approach, the shielding constant, S, is calculated. The effective nuclear charge is then the difference between S and the atomic number, Z. (Note that the results in Table 7.2 and Figure 7.2 were calculated in a slightly different way.) Z = Z S The shielding constant, S, is calculated using the following rules: (1) The electrons of an atom are grouped as follows: (1s) (2s, 2p) (3s, 3p) (3d) (4s, 4p) (4d), and so on. (2) Electrons in higher groups (to the right) do not shield those in the lower groups. (3) For ns and np valence electrons a) Electrons in the same ns, np group contribute 0.35 (for 1s 0.30 works better). b) Electrons in n 1 groups contribute 0.85. c) Electrons in n 2 groups (and lower) contribute 1.00. (4) For nd and nf electrons, electrons in the same nd or nf group contribute 0.35, and those in groups to the left contribute 1.00. As an example, let us calculate Z for the outermost electron of oxygen: S = (2 0.85) + (5 0.35) = 3.45 Z = 8 3.45 = 4.55 Here is a calculation for a d electron in Ni: Z = 28 [18 1.00] [7 0.35] = 7.55 and for an s electron in Ni: Z = 28 [10 1.00] [16 0.85] [1 0.35] = 4.05 (Here 3s, 3p, and 3d electrons are in the (n 1) groups.) a) Calculate Z for F and Ne. Relate the Z values for O, F, and Ne to their relative atomic radii and ionization energies. b) Calculate Z for one of the 3d electrons of Mn, and compare this with Z for one of the 4s electrons of the element. Do the Z values give us some insight into the ionization of Mn to give the cation?Draw Lewis electron dot structures for CH3Cl (methyl chloride, a topical anesthetic), H2O2 (hydrogen peroxide, with an O-O bond), and NH2OH (with an N-O bond).8.2CYU 8.3CYU 8.4CYU 8.5CYU Draw resonance structures for the bicarbonate ion, HCO3. (a) Does HCO3 have the same number of resonance structures as the CO32 ion? Are any less likely than others? (b) What are the formal charges on the O and C atoms in HCO3? What is the average formal charge on the O atoms? Compare this with the O atoms in CO32. (c) Protonation of HCO3 gives H2CO3. How do formal charges predict where the H+ ion will be attached?Sketch the Lewis structures for CIF2+ and CIF2. How many lone pairs and bond pairs surround the Cl atom in each ion?What is the shape of the dichloromethane (CH2C12) molecule? Predict the Cl C Cl bond angle.Give the electron-pair geometry and molecular shape for BF3 and BF4 What is the effect on the molecular geometry of adding an F ion to BF3 to give BF4?Draw the Lewis structure for lCl2, and then decide on the geometry of the ion.For each of the following pairs of bonds, decide which is more polar. For each polar bond, indicate the positive and negative poles. After making your prediction from the relative atom positions in the periodic table, check your prediction by calculating. X from electronegativity values in Figure 8.11. (a) HF and HI (b) BC and BF (c) CSi and CS Draw the resonance structures for SCN. What are the formal charges on each atom in each resonance structure? What are the bond polarities? Do they agree with the formal charges?For each of the following molecules, decide whether the molecule is polar and which side is positive and which negative: BFCl2, NH2Cl, and SCl2.The electrostatic potential surface for SOCl2 is pictured here. (a) Draw a Lewis electron dot picture for the molecule, and give the formal charge of each atom. (b) What is the molecular geometry of SOCl2? Is it polar?Using the bond dissociation enthalpies in Table 8.8, estimate the enthalpy of combustion of gaseous methane, CH4, to give water vapor and carbon dioxide gas.1.1ACP Do any of the atoms in an ibuprofen molecule have a nonzero formal charge? What is the most polar bond in the molecule? 1.4ACP 1.5ACP 1.6ACP Are there any 120° bond angles in ibuprofen? Any 180° angles? 1.8ACP 2.2ACP Calculate the difference in electronegativity between hydrogen and chlorine (χCl – χH) in hydrogen chloride using average bond dissociation enthalpy values (Table 8.8). Compare your results with those calculated using electro- negativity values from Figure 8.11. Predict the bond dissociation enthalpy for a nitrogen-iodine bond in Nl3 using bond dissociation enthalpy values (Table 8.8) and electronegativity values (Figure 8.11). 3.3ACP Give the periodic group number and number of valence electrons for each of the following atoms. (a) O (b) B (c) Na (d) Mg (e) F (f) S Give the periodic group number and number of valence electrons for each of the following atoms. (a) C (b) Cl (c) Ne (d) Si (e) Se (f) Al For elements in Groups 4A-7A of the periodic table, give the number of bonds an element is expected to form (in an uncharged molecule) if it obeys the octet rule.4PS Draw a Lewis structure for each of the following molecules or ions. (a) NF3 (b) C1O3 (c) HOBr (d) SO32 Draw a Lewis structure for each of the following molecules or ions: (a) CS (b) BF4 (c) HNO2 (where the arrangement of atoms is HONO) (d) OSCl2 (where S is the central atom)Draw a Lewis structure for each of the following molecules: (a) chlorodifluoromethane, CHClF2 (b) propanoic acid, C2H5CO2H (basic structure pictured below) (c) acetonitrile, CH3CN (the framework is H3CCN) (d) allene, H2CCCH2 Draw a Lewis structure for each of the following molecules: (a) methanol, CH3OH (b) vinyl chloride, H2C=CHCl, the molecule from which PVC plastics are made (c) acrylonitrile, H2C=CHCN, the molecule from which materials such as Orion are made Show all possible resonance structures for each of the following molecules: (a) sulfur dioxide SO2 (b) nitrous acid, HNO2 (c) thiocyanic acid, HSCN Show all possible resonance structures for each of the following molecules or ions: (a) nitrate ion, NO3 (b) nitric acid, HNO3 (c) dinitrogen monoxide (nitrous oxide, laughing gas), N2O (where the bonding is in the order NNO)11PS Draw a Lewis structure for each of the following molecules or ions: (a) BrF5 (b) IF3 (c) IBr2 (d) BrF2+Determine the formal charge on each atom in the following molecules or ions: (a) N2H4 (b) PO43 (c) BH4 (d) NH2OH Determine the formal charge on each atom in the following molecules or ions: (a) SCO (b) HCO2 (formate ion) (c) CO32 (d) HCO2H (formic acid)Determine the formal charge on each atom in the following molecules and ions: (a) NO2+ (b) NO2 (c) NF3 (d) HNO3 Determine the formal charge on each atom in the following molecules and ions: (a) SO2 (b) OSCl2 (c) O2SCl2 (d) FSO3 Draw a Lewis structure for each of the following molecules or ions. Describe the electron-pair geometry and molecular geometry around the central atom. (a) NH2C1 (b) Cl2O (O is the central atom) (c) SCN (d) HOF 18PS 19PS The following molecules or ions all have three oxygen atoms attached to a central atom. Draw a Lewis structure for each one, and then describe the electron-pair geometry and molecular geometry around the central atom. Comment on similarities and differences in the series. (a) CO32 (b) NO3 (c) SO32 (d) ClO3 Draw a Lewis structure for each of the following molecules or ions. Describe the electron-pair geometry and molecular geometry around the central atom. (a) ClF2 (b) ClF3 (c) ClF4 (d) CIF5 Draw a Lewis structure for each of the following molecules or ions. Describe the electron-pair geometry and molecular geometry' around the central atom. (a) SiF62 (b) PF5 (c) SF4 (d) XeF4 Give approximate values for the indicated bond angles. (a) OSO angle in SO2 (b) FBF angle in BF3 (c) ClCCl angle in Cl2CO (d) HCH (angle 1) and CCN (angle 2) acetonitrile Give approximate values for the indicated bond angles: (a) ClSCl in SCl2 (b) NNO in N2O (c) Bond angles 1, 2, and 3 in vinyl alcohol (a component of polymers and a molecule found in outer space)Phenylalanine is one of the natural amino acids and is a breakdown product of the artificial sweetener aspartame. Estimate the values of the indicated angles in the amino acid. Explain why the CH2CH(NH2)CO2H chain is not linear.Acetylacetone has the structure shown here. Estimate the values of the indicated angles.For each pair of bonds, indicate the more polar bond, and use an arrow to show the direction of polarity in each bond. (a) CO and CN (b) PBr and PCl (c) BO and BS (d) BI and BI For each of the bonds listed below, tell which atom is the more negatively charged. (a) CN (b) CH (c) CBr (d) SO Urea, (NH2)2CO, is used in plastics and fertilizers. It is also the primary nitrogen-containing substance excreted by humans. (a) Which bonds in the molecule are polar, and which are nonpolar? (b) Which is the most polar bond in the molecule? Which atom is the negative end of the bond dipole?Considering both formal charges and bond polarities, predict on which atom or atoms the negative charge resides in the following anions: (a) OH (b) BH4 (c) CH3CO2 Considering both formal charge and bond polarities, predict on which atom or atoms the positive charge resides in the following cations: (a) H3O+ (b) NH4+ (c) NO2+ (d) NF4+Three resonance structures are possible for dinitrogen monoxide, N2O. (a) Draw the three resonance structures. (b) Calculate the formal charge on each atom in each resonance structure. (c) Based on formal charges and electronegativity, predict which resonance structure is the most reasonable.Three resonance structures are possible for the thiocyanate ion, SCN. (a) Draw the three resonance structures. (b) Calculate the formal charge on each atom in each resonance structure. (c) Based on formal charges and electronegativity, predict which resonance structure most closely approximates the bonding in this ion? (d) What are the similarities and differences of bonding in SCN compared to the bonding in OCN (page 382).Compare the electron dot structures of the hydrogen carbonate ion and nitric acid. (a) Are these species isoelectronic? (b) How many resonance structures does each species have? (c) What are the formal charges of each atom in these species? (d) Compare the two species with respect to their acid-base behavior. (Can either or both species behave as a base and form a bond to H+?)Compare the electron dot structures of the carbonate (CO32) and borate (BO33) ions. (a) Are these ions isoelectronic? (b) How many resonance structures does each ion have? (c) What are the formal charges of each atom in these ions? (d) If an H+ ion attaches to CO32 to form the bicarbonate ion, HCO3, does it attach to an O atom or to the C atom?The chemistry of the nitrite ion and HNO2: (a) Two resonance structures are possible for NO2. Draw these structures, and then find the formal charge on each atom in each resonance structure. (b) In forming the acid HNO2 an H+ ion attaches to the O atom and not the N atom of NO2. Explain why you would predict this result. (c) Two resonance structures are possible for HNO2. Draw these structures, and then find the formal charge on each atom in each resonance structure. Is either of these structures strongly preferred over the other?Draw the resonance structures for the formate ion, HCO2, and find the formal charge on each atom. If an H+ ion is attached to HCO2 (to form formic acid), does it attach to C or O?39PS Consider the following molecules: (a) CH4 (b) NH2Cl (c) BF3 (d) CS2 (i) In which compound are the bonds most polar? (ii) Which compounds are not polar? (iii) Are the H atoms in NH2Cl negative or positive?Which of the following molecules is(are) polar? For each polar molecule indicate the direction of polaritythat is, which is the negative end, and which is the positive end of the molecule. (a) BeCl2 (b) HBF2 (c) CH3Cl (d) SO3 42PS Give the bond order for each bond in the following molecules or ions: (a) CH2O (b) SO32 (c) NO2+ (d) NOCl 44PS In each pair of bonds, predict which is shorter. (a) BCl or CaCl (b) SnO or CO (c) PS or PO (d) C=O or C=N In each pair of bonds, predict which is shorter. (a) SiN or SiO (b) SiO or CO (c) CF or CBr (d) The CN bond or the CN bond in H2NCH2CN 47PS Compare the carbon-oxygen bond lengths in the formate ion (HCO2), in methanol (CH3OH), and in the carbonate ion (CO32). In which species is the carbon-oxygen bond predicted to be longest? In which is it predicted to be shortest? Explain briefly.Consider the carbon-oxygen bond in formaldehyde (CH2O) and carbon monoxide (CO). In which molecule is the CO bond shorter? In which molecule is the CO bond stronger?Compare the nitrogen-nitrogen bond in hydrazine, H2NNH2, with that in laughing gas, N2O. In which molecule is the nitrogen-nitrogen bond shorter? In which is the bond stronger?Ethanol can be made by the reaction of ethylene and water: H2C=CH2(g) + H2O(g) CH3CH2OH(g) Use bond dissociation enthalpies to estimate the enthalpy change in this reaction. Compare the value obtained to the value calculated from enthalpies of formation.Methanol can be made by partial oxidation of methane using O2 in the presence of a catalyst: 2 CH4(g) + O2(g) 2 CH3OH() Use bond dissociation enthalpies to estimate the enthalpy change for this reaction. Compare the value obtained to the value calculated using standard enthalpies of formation.Hydrogenation reactions, which involve the addition of H2 to a molecule, are widely used in industry to transform one compound into another. For example, 1-butene (C4H8) is converted to butane (C4H10) by addition of H2. Use the bond dissociation enthalpies in Table 8.8 to estimate the enthalpy change for this hydrogenation reaction.Phosgene, Cl2CO, is a highly toxic gas that was used as a weapon in World War 1. Using the bond dissociation enthalpies in Table 8.8, estimate the enthalpy change for the reaction of carbon monoxide and chlorine to produce phosgene. CO(g) + Cl2(g) Cl2CO(g)The compound oxygen difluoride is quite reactive, giving oxygen and HF when treated with water: OF2(g) + H2O(g) O2(g) + 2 HF(g) rH = 318 kl/mol-rxn Using bond dissociation enthalpies, calculate the bond dissociation enthalpy of the OF bond in OF2.Oxygen atoms can combine with ozone to form oxygen: O3(g) + O(g) 2 O2(g) rH = 392 kJ/mol-rxn Using rH and the bond dissociation enthalpy data in Table 8.8, estimate the bond dissociation enthalpy for the oxygen-oxygen bond in ozone, O3. How does your estimate compare with the energies of an OO single bond and an O=O double bond? Does the oxygen-oxygen bond dissociation enthalpy in ozone correlate with its bond order?57GQ 58GQ Which of the following compounds or ions do not have an octet of electrons surrounding the central atom: BF4, SiF4, SeF4, BrF4, XeF4?60GQ Draw resonance structures for the formate ion, HCO2 and then determine the CO bond order in the ion.62GQ 63GQ What is the principle of electroneutrality? Use this rule to exclude a possible resonance structure of CO2.65GQ Draw resonance structures for the SO2 molecule, and determine the formal charges on the S and O atoms. Are the SO bonds polar, and is the molecule as a whole polar? If so, what is the direction of the net dipole in SO2? Is your prediction confirmed by the electrostatic potential surface? Explain briefly.What are the orders of the NO bonds in NO2 and NO2+? The nitrogen-oxygen bond length in one of these ions is 110 pm and 124 pm in the other. Which bond length corresponds to which ion? Explain briefly.Which has the greater ONO bond angle, NO2 or NO2+? Explain briefly.Compare the FClF angles in CIF2+ and ClF2. Using Lewis structures, determine the approximate bond angle in each ion. Which ion has the greater bond angle?Draw an electron dot structure for the cyanide ion, CN. In aqueous solution, this ion interacts with H+ to form the acid. Should the acid formula be written as HCN or CNH?Draw the electron dot structure for the sulfite ion, SO32. In aqueous solution, the ion interacts with H+. Predict whether a H+ ion will attach to the S atom or the O atom of SO32.Dinitrogen monoxide, N2O, can decompose to nitrogen and oxygen gas: 2 N2O(g) 2 N2(g) + O2(g) Use bond dissociation enthalpies to estimate the enthalpy change for this reaction.The equation for the combustion of gaseous methanol is 2 CH3OH(g) + 3 O2(g) 2 CO2(g) + 4 H2O(g) (a) Using the bond dissociation enthalpies in Table 8.8, estimate the enthalpy change for this reaction. What is the enthalpy of combustion of one mole of gaseous methanol? (b) Compare your answer in part (a) with the value of tHcalculated using enthalpies of formation data.The cyanate ion, OCN, has the least electronegative atom, C, in the center. The unstable fulminate ion, CNO, has the same molecular formula, but the N atom is in the center. (a) Draw the three possible resonance structures of CNO. (b) On the basis of formal charges, decide on the resonance structure with the most reasonable distribution of charge (c) Mercury fulminate is so unstable it is used in blasting caps for dynamite. Can you offer an explanation for this instability? (Hint: Are the formal charges in any resonance structure reasonable in view of the relative electronegativities of the atoms?)Vanillin is the flavoring agent in vanilla extract and in vanilla ice cream. Its structure is shown here: (a) Give values for the three bond angles indicated. (b) Indicate the shortest carbon-oxygen bond in the molecule. (c) Indicate the most polar bond in the molecule.Explain why (a) XeF2 has a linear molecular structure and not a bent one. (b) ClF3 has a T-shaped structure and not a trigonal-planar one.The formula for nitryl chloride is ClNO2 (in which N is the central atom). (a) Draw the Lewis structure for the molecule, including all resonance structures. (b) What is the NO bond order? (c) Describe the electron-pair and molecular geometries, and give values for all bond angles. (d) What is the most polar bond in the molecule? Is the molecule polar? (e) The computer program used to calculate electrostatic potential surfaces gave the following charges on atoms in the molecule: A = 0.03, B = 0.26, and C = +0.56. Identify the atoms A, B, and C. Are these calculated charges in accord with your predictions?Hydroxyproline is a less-common amino acid. (a) Give approximate values for the indicated bond angles. (b) Which are the most polar bonds in the molecule?Amides are an important class of organic molecules. They are usually drawn as sketched here, but another resonance structure is possible. (a) Draw a second resonance structure of the structure above. Do you think that this should be a significant contributor to the bonding? Explain your answer. (b) The HNH angle is close to 120 in this molecule. Does this fact influence your thoughts on the importance of this structure?81GQ The molecule shown here. 2-furylmelhanethiol, is responsible for the aroma of coffee: (a) What are the formal charges on the S and O atoms? (b) Give approximate values of angles 1, 2, and 3. (c) Which are the shorter carbon-carbon bonds in the molecule? (d) Which bond in this molecule is the most polar? (e) Is the molecule polar or nonpolar? (f) The four C atoms of the ring are all in a plane. Is the O atom in that same plane (making the five-member ring planar), or is the O atom bent above or below the plane?Dihydroxyacetone is a component of quick-tanning lotions. (It reacts with the amino acids in the upper layer of skin and colors them brown in a reaction similar to that occurring when food is browned as it cooks.) (a) Use bond dissociation enthalpies to estimate the enthalpy change for the following reaction. Is the reaction exothermic or endothermic? (b) Are dihydroxyacetone and acetone polar molecules? (c) A proton (H+) can be removed from a molecule of dihydroxyacetone with strong bases (which is in part what happens in the tanning reaction). Which H atoms are the most positive.It is possible to draw three resonance structures for HNO3, one of which contributes much less to the resonance hybrid than the other two. Sketch the three resonance structures, and assign a formal charge to each atom. Which one of your structures is the least important?Acrolein is used to make plastics. Suppose this compound can be prepared by inserting a carbon monoxide molecule into the CH bond of ethylene. (a) Which is the stronger carbon-carbon bond in acrolein? (b) Which is the longer carbon-carbon bond in acrolein? (c) Is ethylene or acrolein polar? (d) Use bond dissociation enthalpies to predict whether the reaction of CO with C2H4 to give acrolein is endothermic or exothermic.Molecules in space: (a) In addition to molecules such as CO, HCl, H2O, and NH3, glycolaldehyde has been detected in outer space. Is the molecule polar? (b) Where do the positive and negative charges lie in the molecule? (c) One molecule found in the 1995 Hale-Bopp comet is HC3N. Suggest a structure for this molecule.1,2-Dichloroethylene can be synthesized by adding Cl2 to the carbon-carbon triple bond of acetylene. Using bond dissociation enthalpies, estimate the enthalpy change for this reaction in the gas phase.The molecule pictured below is epinephrine, a compound used as a bronchodilator and antiglaucoma agent. (a) Give a value for each of the indicated bond angles. (b) What are the most polar bonds in the molecule?You are doing an experiment in the laboratory and want to prepare a solution in a polar solvent. Which solvent would you choose, methanol (CH3OH) or toluene (C6H5CH3)? Explain your choice.90IL A paper published in the research Journal Science in 2007 (S. Vallina and R. Simo, Science, Vol. 315, p. 506, January 26, 2007) reported studies of dimethylsulfide (DMS), an important green-house gas that is released by marine phytoplankton. This gas represents the largest natural source of atmospheric sulfur and a major precursor of hygroscopic (i.e., cloud-forming) particles in clean air over the remote oceans, thereby acting to reduce the amount of solar radiation that crosses the atmosphere and is absorbed by the ocean. (a) Sketch the Lewis structure of dimethylsulfide, CH3SCH3, and list the bond angles in the molecule. (b) Use electronegativities to decide where the positive and negative charges lie in the molecule. Is the molecule polar? (c) The mean seawater concentration of DMS in the ocean in the region between 15 north latitude and 15 south latitude is 2.7 nM (nanomolar). How many molecules of DMS are present in 1.0 m3 of seawater?Uracil is one of the bases in RNA, a close relative of DNA. (a) What are the values of the OCN and CNH angles? (b) There are two carbon-carbon bonds in the molecule. Which is predicted to be shorter? (c) If a proton (H+) attacks the molecule decide on the basis of the electrostatic potential surface to which atom or atoms it could be attached.Guanine is present in both DNA and RNA. (a) What is the most polar bond in the molecule? (b) What is the N-C=N angle in the 6-member ring? (c) What is the N-C=N angle in the 5-member ring? (d) What is the bond angle around the N atom of the NH3 group?94IL 95SCQ 96SCQ Bromine-containing species play a role in environmental chemistry. For example, they are evolved in volcanic eruptions. (a) The following molecules are important in bromine environmental chemistry: HBr, BrO, and HOBr. Which is an odd-electron molecule? (b) Use bond dissociation enthalpies to estimate rH for three reactions of bromine: Br2(g) 2 Br(g) 2 Br(g) + O2(g) 2 BrO(g) BrO(g) + H2O(g) HOBr(g) + OH(g) (c) Using bond dissociation enthalpies, estimate the standard enthalpy of formation of HOBr(g) from H2(g), O2(g), and Br2(g). (d) Are the reactions in parts (b) and (c) exothermic or endothermic?Acrylamide, H2C=CHCONH2, is a known neurotoxin and possible carcinogen. It was a shock to all consumers of potato chips and french fries a few years ago when it was found to occur in those products. (a) Sketch the molecular structure of acrylamide and identify all bond angles. (b) Indicate which carbon-carbon bond is the stronger of the two. (c) Is the molecule polar or nonpolar? (d) The amount of acrylamide found in potato chips is 1.7 mg/kg. If a serving of potato chips is 28 g, how many moles of acrylamide are you consuming?Use valence bond theory to describe the bonding in methylamine. CH3NH2.Identify the hybridization of each underlined atom in the following compounds and ions: (a) B_H4 (b) H2C_=C_HC_H3 (c) BCl3 Use valence bond theory to describe the bonding in acetone, CH3COCH3.What is the electron configuration of the H2+ ion? Compare the bond order of this ion with He2+ and H2. Do you expect H2+ to exist?Could the anion Li2 exist? What is the ions bond order?The cations O2+ and N2+ are formed when molecules of O2 and N2 are subjected to intense, high-energy solar radiation in Earths upper atmosphere. Write the electron configuration for O2+. Predict its bond order and magnetic behavior.Photoelectron spectroscopy is s1milar to the photoelectric effect (Section 6.2). However, in the photoelectric effect, electrons are ejected when light strikes the surface of a(n)What is the energy of a photon with a wavelength of 58.4 nm in kilojoules/mole?Using the accompanying figure, state which molecular orbital (2s, 2p, or 2p) has an ionization energy of 15.6 eV.The kinetic energy of an electron ejected from the 2s molecular orbital of N2 using 58.4 nm radiation is 4.23 1019 J. What is the ionization energy, in both kJ/mol and eV, of an electron from this orbital?The N2+ ions that are formed when electrons with ionization energies of 15.6 eV and 16.7 eV are ejected have longer bond lengths than the ion when an electron with an ionization energy of 18.6 eV is created. Why?What is the empirical formula of Tynan purple?Butter yellow absorbs light with a wavelength of 408 nm, whereas the nitrated form absorbs at 478 nm. Which absorbs the higher energy light?2.3ACP Draw the Lewis structure for chloroform, CHCl3. What are its electron-pair and molecular geometries? What orbitals on C, H, and Cl overlap to form bonds involving these elements?Draw the Lewis structure for NF3. What are its electron-pair and molecular geometries? What is the hybridization of the nitrogen atom? What orbitals on N and F overlap to form bonds between these elements?Draw the Lewis structure for hydroxylamine, H2NOH. What is the hybridization for nitrogen and oxygen in this molecule? What orbitals overlap to form the bond between nitrogen and oxygen?Draw the Lewis structure for 1, 1-dimethylhydrazine [(CH3)2NNH2, a compound used as a rocket fuel]. What: is the hybridization for the two nitrogen atoms in this molecule? What orbitals overlap to form the bond between the nitrogen atoms?Draw the Lewis structure for carbonyl fluoride, COF2. What are the electron-pair geometry and molecular geometry around the central atom? What is the hybridization of the carbon atom? What orbitals overlap to form the and bonds between carbon and oxygen?s Draw the Lewis structure for acetamide, CH3CONH2. What are the electron-pair geometry and molecular geometry around the two C atoms? What is the hybridization of each of the C atoms? What orbitals overlap to form the and bonds between carbon and oxygen?Specify the electron-pair and molecular geometry for each underlined atom in the following list. Describe the hybrid orbital set used by this atom in each molecule or ion. (a) BBr3 (b) CO2 (c) CH2Cl2 (d) CO32 Specify the electron-pair and molecular geometry for each underlined atom in the following list. Describe the hybrid orbital set used by this atom in each molecule or ion. (a) CSe2 (b) SO2 (c) CH2O (d) NH4ss 9PS What is the hybrid orbital set used by each of the underlined atoms in the following molecules? (a) (b) (c)Draw the Lewis structures of the acid HPO2F2 and its anion PO2F2. What is the molecular geometry and hybridization for the phosphorus atom in each species? (H is bonded to an O atom in the acid.)Draw the Lewis structures of the arid HSO3F and its anion SO3F. What is the molecular geometry and hybridization for the sulfur atom in each species? (H is bonded to an O atom in the arid.)What is the hybridization of the carbon atom in phosgene, Cl2CO? Give a complete description of the and bonding in this molecule.What is the hybridization of the carbon atoms in benzene, C6H6? Describe the and bonding in this compound.What is the electron-pair and molecular geometry around the central S atom in thionyl chloride, SOCl2? What is the hybridization of sulfur in this compound?What is the electron-pair and molecular geometry around the central S atom in sulfuryl chloride. SO2Cl2? What is the hybridization of sulfur in this compound?17PS For each compound below, decide whether cis and trans isomers are possible. If isomerism is possible, draw the other isomer.Molecular Orbital Theory (See Examples 9.49.6.) The hydrogen molecular ion, H2+, can be detected spectroscopically. Write the electron configuration of the ion in molecular orbital terms. What is the bond order of the ion? Is the hydrogenhydrogen bond stronger or weaker in H2+ than in H2s?Give the electron configurations for the ions Li2+ and Li2 in molecular orbital terms. Compare the LiLi bond order in these ions with the bond order in Li2.Calcium carbide, CaC2, contains the acetylide ion, C22. Sketch the molecular orbital energy level diagram for the ion and the electron dot strucure. (a) How many net and bonds does the ion have? (b) What is the carboncarbon bond order? (c) Compare the valence bond and MO pictures with regard to the number of and bonds and the bond order. (d) How has the bond order changed on adding electrons to C2 to obtain C22? (e) Is the C22 ion paramagnetic?Platinum hexafluoride is an extremely strong oxidizing agent. It can even oxidize oxygen, its reaction with O2 giving O2+PtFt6. Sketch the molecular orbital energy level diagram for the O2+ ion. How many net and bonds does the ion have? What is the oxygen-oxygen bond order? How has the bond order changed on taking away electrons from O2 to obtain O2+? Is the O2+ ion paramagnetic?When sodium and oxygen react, one of the products obtained is sodium peroxide, Na2O2. The anion in this compound is the peroxide ion, O22. Write the electron configuration for this ion in molecular orbital terms, and draw the electron dot structure. (a) Compare the ion with the O2 molecule with respect to the following: magnetic character, net number of and bonds, bond order, and oxygen-oxygen bond length. (b) Compare the valence bond and MO pictures with regard to the number of and bonds and the bond order.When potassium and oxygen react, one of the products obtained is potassium superoxide, KO2. The anion in this compound is the superoxide ion. O2. Write the electron configuration for this ion in molecular orbital terms, and then compare it with the electron configuration of the O2 molecule with respect to the following criteria: (a) magnetic character (b) net number of and bonds (c) bond order (d) oxygenoxygen bond length A closed-circuit breathing apparatus that generates its own oxygen. One source of oxygen is potassium superoxide (KO2). Both carbon dioxide and moisture exhaled by the wearer into the breathing tube react with the KO2 to generate oxygen.Among the following, which has the shortest bond and which has the longest: Li2, B2, C2, N2, O2?Consider the following list of small molecules and ions: C2 O2, CN, O2. CO, NO, NO+, C22, OF. Identify (a) all species that have a bond order of 3 (b) all species that are paramagnetic (c) species that have a fractional bond order 27PS The nitrosyl ion. NO+, has an interesting chemistry. Assume the molecular orbital diagram shown in Figure 9.16 applies to NO+. (a) Is NO+ diamagnetic or paramagnetic? If paramagnetic, how many unpaired electrons does it have? (b) What is the highest-energy molecular orbital (HOMO) occupied by electrons? (c) What is the nitrogen-oxygen bond order? (d) Is the NO bond in NO stronger or weaker than the bond in NO?These questions are not designated as to type or location in the chapter. They may combine several concepts. Draw the Lewis structure for AlF4. What are its electron-pair and molecular geometries? What orbitals on Al and F overlap to form bonds between these elements? What are the formal charges on the atoms? Is this a reasonable charge distribution?What is the OSO angle and the hybrid orbital set used by sulfur in each of the following molecules or ions? (a) SO2 (b) SO3 (c) SO32 (d) SO42 Do all have the same value for the OSO angle? Does the S atom in all these species use the same hybrid orbitals?Sketch the resonance structures for the nitrite ion, NO2. Describe the electron-pair and molecular geometries of the ion. From these geometries, decide on the OMO bond angle, the average NO bond order, and the N atom hybridization.Sketch the resonance structures for the nitrate ion, NO3. Is the hybridization of the N atom the same or different in each structure? Describe the orbitals involved in bond formation by the central N atom.Sketch the resonance structures for the N2O molecule. Is the hybridization of the N atoms the same or different in each structure? Describe the orbitals involved in bond formation by the central N atom.Compare the structure and bonding in CO2 and CO32 with regard to the OCO bond angle, the CO bond order, and the C atom hybridization.Numerous molecules are detected in deep space. Three of them are illustrated here. (a) Are these compounds isomers? (b) Indicate the hybridization of each C atom in each molecule. (c) What is the value of the HCH angle in each of the three molecules? (d) Which of these molecules is/are polar? (e) Which molecule should have the strongest carbon-carbon bond? The strongest carbon-oxygen bond?Acrolein, a component of photochemical smog, has a pungent odor and irritates eyes and mucous membranes. (a) What are the hybridizations of carbon atoms 1 and 2? (b) What are the approximate values of angle A, B, and C? (c) Is cis-trans isomerism possible here?The organic compound below is a member of a class known as oximes. (a) What are the hybridizations of the two C atoms and of the N atom? (b) What is the approximate CNO angle?The compound sketched below is acetylsalicylic acid, commonly known as aspirin. (a) What are the approximate values of the angles marked A, B, C, and D? (b) What hybrid orbitals are used by carbon atoms 1, 2, and 3ss?Phosphoserine is a less-common amino acid. (a) Identify the hybridizations of atoms I through 5. (b) What are the approximate values of the bond angles A, B. C, and D? (c) What are the most polar bonds in the molecule?Lactic acid is a natural compound found in sour milk. (a) How many bond occur in lactic acid? How many u bonds? (b) What is the hybridization of atoms 1, 2, and 3? (c) Which CO bond is the shortest in the molecule? Which CO bond is the strongest? (d) What are the approximate value of the bond angles A, B, and C?Cinnamaldehyde ocaus naturally in cinnamon oil. (a) What is the most polar bond in the molecule? (b) How many bonds and how many bonds are there? (c) Is cis-trans isomerism possible? If so, draw the isomers of the molecule. (d) Give the hybridization of the C atoms in the molecule. (e) What are the values of the bond angles 1, 2, and 3 ?The ion Si2 was reported in a laboratory experiment in 1996. (a) Using molecular orbital theory, predict the bond order for the ion. (b) Is the ion paramagnetic or diamagnetic? (c) What is the highest energy molecular orbital that contains one or more electrons?The simple valence bond picture of O2 does not agree with the molecular orbital view. Compare these two theories with regard to the peroxide ion, O22. (a) Draw an electron dot structure for O22. What is the bond order of the ion? (b) Write the molecular orbital electron configuration for O22. What is the bond order based on this approach? (c) Do the two theories of bonding lead to the same magnetic character and bond order fo r O22 ss?Nitrogen, N2, can ionize to form N2+ or add an electron to give N2. Using molecular orbital theory, compare these species with regard to (a) their magnetic character, (b) net number of bonds, (c) bond order, (d) bond length, and (e) bond strength.Which of the homonuclear, diatomic molecules of the second-period elements (from Li2 to Ne2) are paramagnetic? Which have a bond order of 1? Which have a bond order of 2? Which diatomic molecule has the highest bond order?Which of the following molecules or ions are para-magnetic? What is the highest occupied molecular orbital (HOMO) in each one? Assume the molecular orbital diagram in Figure 9.16 applies to all of them. (a) NO (b) OF (c) O22 (d) Ne2+47GQ The structure of amphetamine, a stimulant, is shown below. (Replacing one H atom on the NH2, or amino, group with CH3 gives methamphetamine a particularly dangerous drug commonly known as speed.) (a) What are the hybrid orbitals used by the C atoms of the C6 ring. by the C atoms of the side chain, and by the N atom? (b) Give approximate values for the bond angles A, B, and C. (c) How many bonds and bonds are in the molerule? (d) Is the molecule polar or nonpolar? (e) Amphetamine reacts readily with a proton (H+) in aqueous solution. Where does this proton attach to the molecule? Explain how the electrostatic potential map predicts this site of protonation.Menthol is used in soaps, perfumes, and foods. It is present in the common herb mint, and it can be prepared from turpentine. (a) What are the hybridizations used by the C atoms in the molecule? (b) What is the approximate COH bond angle? (c) Is the molecule polar or nonpolar? (d) Is the six-member carbon ring planar or non-planar? Explain why or why not.50GQ Suppose you carry out the following reaction of ammonia and boron trifluoride in the laboratory. (a) What is the geometry of the boron atom in BF3? In H3NBF3? (b) What is the hybridization of the boron atom in the two compounds? (c) Considering the structures and bonding of NH3 and BF3, why do you expect the nitrogen on NH3 to donate an electron pair to the B atom of BF3? (d) BF3 also reacts readily with water. Based on the ammonia reaction above, speculate on how water can interact with BF3.Ethylene oxide is an intermediate in the manufacture or ethylene glycol (antifreeze) and polyester polymers. More than 4 million tons are produced annually in the United States. The molecule has a three-member ring of two C atoms and an O atom. (a) What are the bond angles in the ring? Comment on the relation between the bond angles expected based on hybridization an d the bond angles expected for a three-member ring. (b) Is the molecule polar? Based on the electrostatic poten1ial map shown below. where do the neg-alive and positive charges lie in the molecule? Polarity: It is a well separation of electric charge leading to a molecule or chemical compounds having an electrical dipole moment. Generally the polar molecules must contain polar bonds due to a different in electronegative between the bonded atoms. The electrostatic potential map clearly to explain, the oxygen atom has more negative () charge and other side has less positive () charge, so this molecule is a more polar nature.The sulfamate ion, H2NSO3, can be thought of as having been formed from the amide ion, NH2, and sulphur trioxide, SO3. (a) What are the electron-pair and molecular geometries or the amide ion and or SO3? What are the hybridizations of the N and S atoms, respectively? (b) Sketch a structure for the sulfamate ion, and estimate the bond angles. (c) What changes in hybridization do you expect for N and S in the course of the reaction NH2 + SO3 H2NSO3? (d) Is SO3 the donor of an electron pair or the acceptor of an electron pair in the reaction with amide ion? Does the electrostatic potential map shown below confirm your prediction?The compound whose structure is shown here is acetyl acetone. It exists in two forms: the enol form and the keto form. The molecule reacts with OH to form an anion, [CH3COCHCOCH3] (often abbreviated acac for acetylacetonate ion). One or the most interesting aspects of this anion is that one or more of them can react with transition metal cations to give stable, highly colored compounds. (a) Are the keto and enol forms of acetylacetone resonance forms? Explain your answer. (b) What is the hybridization or each atom (except H) in the enol form? What changes in hybridization occur when it is transformed into the keto form? (c) What are the electron-pair geometry and molecular geometry around each C atom in the keto and enol forms? What changes in geometry occur when the keto form changes to the enol form? (d) Draw three possible resonance structures for the acac ion. (e) Is cis-trans isomerism possible in either the enol or the keto form of acetylacetone? (f) Is the enol form of acetylacetone polar? Where do the positive and negative charges lie in the molecule?55IL Carbon dioxide (CO2), dinitrogen monoxide (N2O), the azide ion (N3), and the cyanate ion (OCN) have the same geometry and the same number of valence shell electrons. However, there are significant differences in their electronic structures. (a) What hybridization is assigned to the central atom in each species? Which orbitals overlap to form the bonds between atoms in each structure. (b) Evaluate the resonance structures of these four species. Which most closely describe the bonding in these species? Comment on the differences in bond lengths and bond orders that you expect to see based on the resonance structures.Draw the two resonance structures that describe the bonding in SO2. Then describe the bonding in this compound using MO theory. How does MO theory rationalize the bond order of 1.5 for the two SO bonds in this compound?Draw a Lewis structure for diimide, HNNH. Then, using valence bond theory, describe the bonding in this compound. What orbitals overlap to form the bond between nitrogen atoms in this compound?59SCQ Consider the three fluorides BF4, SiF4, and SF4. (a) Identify a molecule that is isoelectronic with BF4. (b) Are SiF4 and SF4 isoelectronic? (c) What is the hybridization of the central atom in BF4 and SiF4?When two amino acids react with each other, they form a linkage called an amide group, or a peptide link. (If more linkage. are added, a protein or polypeptide is formed.) (a) What are the hybridizations of the C and N atoms in the peptide linkage? (b) Is the structure illustrated the only resonance structure possible for the peptide linkage? If another resonance structure is possible. compare it with the o ne shown. Decide which is the more important structure. (c) The computer-generated structure shown here, which contains a peptide linkage, shows that this linkage is flat. This is an important feature of proteins. Speculate on reasons that the CONH linkage is planar. What are the sites of positive and negative charge in this dipeptide?What is the connection between bond order, bond length, and bond energy? Use ethane (C2H6), ethylene (C2H4), and acetylene (C2H2) as examples.When is it desirable to use MO theory rather than valence bond theory?Show how valence bond theory and molecular orbital theory rationalize the OO bond order of 1.5 in ozone.Three of the four molecular orbitals for cyclobutadiene are pictured here. Place them in order of increasing energy. (See Figures 9.13, 9.15, 9.16, and 9.18 and the relation of orbital energy and nodes.)Lets look more closely at the process of hybridization. (a) What is the relationship between the number of hybrid orbitals produced and the number of atomic orbitals used to create them? (b) Do hybrid atomic orbitals form between different p orbitals without involving 5 orbitals? (c) What is the relationship between the energy of hybrid atomic orbitals and the atomic orbitals from which they are formed?Borax has the molecular formula Na2B4O5(OH)4. The structure of the anion in this compound is shown below. What is the electron pair geometry and molecular geometry surrounding each of the boron atoms in this anion? What hybridization can be assigned to each of the boron atoms? What is the formal charge of each boron atom?A model of the organic compound allene is shown below. (a) Explain why the allene molecule is not flat. That is. explain why the CH2 groups at opposite ends do not lie in the same plane. (b) What is the hybridization of each of the carbon atoms in allene? (c) What orbitals overlap to form the bonds between carbon atoms in allene?69SCQ 70SCQ Bromine forms a number of oxides of varying stability. (a) One oxide has 90.90% Br and 9.10% O. Assuming its empirical and molecular formulas are the same, draw a Lewis structure of the molecule and specify the hybridization of the central atom (O). (b) Another oxide is unstable BrO. Assuming the molecular orbital diagram in Figure 9. 16 applies to BrO, write its electron configuration (where Br uses 45 and 4p orbitals). What is the highest occupied molecular orbital (HOMO) for the molecule?72SCQ Urea reacts with malonic acid to produce barbituric acid, a member of the class of compounds called phenobarbitals, which are widely prescribed as sedatives. (a) What bonds are broken and what bonds are made when malonic acid and urea combine to make barbituric acid? Is the reaction predicted to be exo- or endothermic? (b) Write a balanced equation for the reaction. (c) Specify the bond angles in barbituric acid. (d) Give the hybridisation of the C atoms in barbituric acid. (e) What is(are) the most polar bond(s) in barbituric acid? (f) Is the molecule polar?At the summit of Mount Everest (altitude = 8848 m), atmospheric pressure is 0.29 atm (or 29% of the pressure at sea level). Convert the pressure into its corresponding value in units of mm Hg, bars, and kilopascals.A large balloon contains 65.0 L of helium gas at 25 C and a pressure of 745 mm Hg. The balloon ascends to 3000 m, at which the external pressure has decreased by 30.%. What would be the volume of the balloon, assuming it expands so that the internal and external pressures are equal? (Assume the temperature is still 25 C.)10.3CYU You have a 22-L cylinder of helium at a pressure of 150 atm (above atmospheric pressure) and at 31 C. How many balloons can you fill, each with a volume of 5.0 L, on a day when the atmospheric pressure is 755 mm Hg and the temperature is 22 C?10.5CYU 10.6CYU At 1.00 atm and 25 C, the density of dry air is 1.18 g/L. If the air is heated to 55 C at constant pressure, what is its density?A 0.105-g sample of a gaseous compound has a pressure of 561 mm Hg in a volume of 125 mL at 23.0 C. What is its molar mass?10.9CYU The halothane-oxygen mixture described in this Example is placed in a 5.00-L tank at 25.0 C. What is the total pressure (in mm Hg) of the gas mixture in the tank? What are the partial pressures (in mm Hg) of the gases?10.11CYU 10.12CYU 1.1ACP 1.2ACP At sea level, atmospheric pressure is 1.00 atm. Calculate the density (in g/L) of helium at this pressure and 25 C.2.2ACP To stay aloft, a blimp must achieve neutral buoyancy; that is, its density must equal that of the surrounding air. The density of the blimp is its total weight (blimp, helium and air, passengers, and ballast) divided by its volume. Assume that the gross weight of the blimp includes the blimps structure and the helium, but does not include the air in the ballonets or the weights of the passengers and ballast. If the ballonets are filled with 12,000 ft3 (340 m3) of air at 1.00 atm and 25 C, what additional weight (of passengers and ballast) is required for neutral buoyancy?Nitrogen gas is produced not only by NaN3 decomposition, but also in the reaction that captures the sodium by-product. You need to fill a 75 L airbag at 25 °C to a pressure of 3.0 atm. What mass of NaN3 is required? What mass of KNO3 needs to be in the bag to capture the sodium byproduct? 3.2ACP Pressure (See Section 10.1 and Example 10.1.) The pressure of a gas is 440 mm Hg. Express this pressure in units of (a) atmospheres, (b) bars, and (c) kilopascals.The average barometric pressure at an altitude of 10 km is 210 mm Hg. Express this pressure in atmospheres, bars, and kilopascals.Indicate which represents the higher pressure in each of the following pairs: (a) 534 mm Hg or 0.754 bar (b) 534 mm Hg or 650 kPa (c) 1.34 bar or 934 kPa Put the following in order of increasing pressure: 363 mm Hg, 363 kPa, 0.256 atm, and 0.523 bar.5PS 6PS You have 3.5 L of NO at a temperature of 22.0 C. What volume would the NO occupy at 37 C? (Assume the pressure is constant.)8PS 9PS You have a sample of CO2 in flask A with a volume of 25.0 mL. At 20.5 C, the pressure of the gas is 436.5 mm Hg. To find the volume of another flask, B, you move the CO2 to that flask and find that its pressure is now 94.3 mm Hg at 24.5 C. What is the volume of flask B?You have a sample of gas in a flask with a volume of 250 mL. At 25.5 C, the pressure of the gas is 360 mm Hg. If you decrease the temperature to 5.0 C, what is the gas pressure at the lower temperature?A sample of gas occupies 135 mL at 22.5 C; the pressure is 165 mm Hg. What is the pressure of the gas sample when it is placed in a 252-mL flask at a temperature of 0.0 C?One of the cylinders of an automobile engine has a volume of 400. cm3. The engine takes in air at a pressure of 1.00 atm and a temperature of 15 C and compresses the air to a volume of 50.0 cm3 at 77 C. What is the final pressure of the gas in the cylinder? (The ratio of before and after volumesin this case, 400:50 or 8:1is called the compression ratio.)A helium-filled balloon of the type used in long-distance flying contains 420,000 ft3 (1.2 107 L) of helium. Suppose you fill the balloon with helium on the ground, where the pressure is 737 mm Hg and the temperature is 16.0 C. When the balloon ascends to a height of 2 miles, where the pressure is only 600. mm Hg and the temperature is 33 C, what volume is occupied by the helium gas? Assume the pressure inside the balloon matches the external pressure.Nitrogen monoxide reacts with oxygen to give nitrogen dioxide. 2 NO(g) + O2(g) 2 NO2(g) (a) You wish to react NO and O2 in the correct stoichiometric ratio. The sample of NO has a volume of 150 mL. What volume of O2 is required (at the same pressure and temperature)? (b) What volume of NO2 (at the same pressure and temperature) is formed in this reaction?Ethane bums in air to give H2O and CO2. 2 C2H6(g) + 7 O2(g) 4 CO2(g) + 6 H2O(g) What volume of O2 (L) is required for complete reaction with 5.2 L of C2H6? What volume of H2O vapor (L) is produced? Assume all gases are measured at the same temperature and pressure.A 1.25-g sample of CO2 is contained in a 750.-mL flask at 22.5 C. What is the pressure of the gas?A balloon holds 30.0 kg of helium. What is the volume of the balloon if its pressure is 1.20 atm and the temperature is 22 C?A flask is first evacuated so that it contains no gas at all. Then, 2.2 g of CO2 is introduced into the flask. On warming to 22 C, the gas exerts a pressure of 318 mm Hg. What is the volume of the flask?20PS 21PS 22PS Forty miles above Earths surface, the temperature is 250 K, and the pressure is only 0.20 mm Hg. What is the density of air (in grams per liter) at this altitude? (Assume the molar mass of air is 28.96 g/mol.)24PS A gaseous organofluorine compound has a density of 0.355 g/L at 17 C and 189 mm Hg. What is the molar mass of the compound?26PS A 1 007-g sample of an unknown gas exerts a pressure of 715 mm Hg in a 452-mL container at 23 C. What is the molai mass of the gas?A 0.0130-g sample of a gas with an empirical formula of C4H5 is placed in a 165-mL flask. It has a pressure of 13.7 mm Hg at 22.5 C. What is the molecular formula of the compound?A new boron hydride, BxHy, has been isolated. To find its molar mass, you measure the pressure of the gas in a known volume at a known temperature. The following experimental data are collected: Mass of gas = 12.5 mg Pressure of gas = 24.8 mm Hg Temperature = 25 C Volume of flask = 125 mL Which formula corresponds to the calculated molar mass? (a) B2H6 (b) B4H10 (c) B5H9 (d) B6H10 (e) Bl0H14 Acetaldehyde is a common liquid compound that vaporizes readily. Determine the molar mass of acetaldehyde from the following data: Sample mass = 0.107 g Volume of gas = 125 mL Temperature = 0.0 C Pressure = 331 mm Hg Iron reacts with hydrochloric acid to produce iron(II) chloride and hydrogen gas: Fe(s) + 2 HCl(aq) FeCl2(aq) + H2(g) The H2 gas from the reaction of 2.2 g of iron with excess acid is collected in a 10.0-L flask at 25 C. What is the pressure of the H2 gas in this flask?Silane, SiH4, reacts with O2 to give silicon dioxide and water: SiH4(g) + 2 O2(g) SiO2(s) + 2 H2O() A 5.20-L sample of SiH4 gas at 356 mm Hg pressure and 25 C is allowed to react with O2 gas. What volume of O2 gas, in liters, is required for complete reaction if the oxygen has a pressure of 425 mm Hg at 25 C?33PS The hydrocarbon octane (C8H18) bums to give CO2 and water vapor: 2 C8H18(g) + 25 O2(g) 16 CO2(g) + 18 H2O(g) If a 0.048-g sample of octane burns completely in O2, what will be the pressure of water vapor in a 4.75-L flask at 30.0 C? If the O2 gas needed for complete combustion was contained in a 4.75-L flask at 22 C, what would its pressure be?35PS A self-contained underwater breathing apparatus (SCUBA) uses canisters containing potassium superoxide. The superoxide consumes the CO2 exhaled by a person and replaces it with oxygen. 4 KO2(s) + 2 CO2(g) 2 K2CO3(s) + 3 O2(g) What mass of KO2, in grams, is required to react with 8.90 L of CO2 at 22.0 C and 767 mm Hg?What is the total pressure in atmospheres of a gas mixture that contains 1.0 g of H2 and 8.0 g of Ar in a 3.0-L container at 27 C? What are the partial pressures of the two gases;

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