8.83 Construct a Born-Haber cycle for the formation of the hy- pothetical compound NaCl2, where the sodium ion has a 2+ charge (the second ionization energy for sodium is given in Table 7.2). (a) How large would the lattice energy need to be for the formation of NaCl2 to be exothermic? (b) If we were to estimate the lattice energy of NaCl2 to be roughly equal to that of MgCl2 (2326 kJ/mol from Table 8.1), what value would you obtain for the standard enthalpy of formation, AH, of NaCl2? ing together of Na (g) and Cl (AH=-788 kJ/mol). Notice Table 8.1 lists the lattice energies for a number of ionic compounds. The large itive values indicate that the ions are strongly attracted to one another in ionic solid Pos TABLE 8.1 Lattice Energies for Some Ionic Compounds Lattice Energy (kJ/mol) Lattice Energy (kJ/mo Compound 2526 Compound MgCl2 1030 2127 LiF SrCl2 834 LiCl 730 Lil 3795 MgO 910 NaF 3414 CaO 788 NaCl 3217 SrO 732 NaBr 682 Nal ScN 7547 KF 808 КС. 701 KBr 671 CsCl 657 CsI 600

8.83 Construct a Born-Haber cycle for the formation of the hy- pothetical compound NaCl2, where the sodium ion has a 2+ charge (the second ionization energy for sodium is given in Table 7.2). (a) How large would the lattice energy need to be for the formation of NaCl2 to be exothermic? (b) If we were to estimate the lattice energy of NaCl2 to be roughly equal to that of MgCl2 (2326 kJ/mol from Table 8.1), what value would you obtain for the standard enthalpy of formation, AH, of NaCl2? ing together of Na (g) and Cl (AH=-788 kJ/mol). Notice Table 8.1 lists the lattice energies for a number of ionic compounds. The large itive values indicate that the ions are strongly attracted to one another in ionic solid Pos TABLE 8.1 Lattice Energies for Some Ionic Compounds Lattice Energy (kJ/mol) Lattice Energy (kJ/mo Compound 2526 Compound MgCl2 1030 2127 LiF SrCl2 834 LiCl 730 Lil 3795 MgO 910 NaF 3414 CaO 788 NaCl 3217 SrO 732 NaBr 682 Nal ScN 7547 KF 808 КС. 701 KBr 671 CsCl 657 CsI 600

Chemistry for Engineering Students

4th Edition

ISBN:9781337398909

Author:Lawrence S. Brown, Tom Holme

Publisher:Lawrence S. Brown, Tom Holme

Chapter7: Chemical Bonding And Molecular Structure

Section: Chapter Questions

Problem 7.74PAE: 7.74 In a lattice, a positive ion is often surrounded by eight negative ions. We might reason,...

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Define the term lattice energy. Why, energetically, do ionic compounds form? Fig. 3-8 illustrates the energy changes involved in the formation of MgO(s) and NaF(s). Why is the lattice energy of MgO(s) so different from that of NaF(s)? The magnesium oxide is composed of Mg2+ and O2 ions. Energetically, why does Mg2+O2 form and not Mg+O? Why doesnt Mg3+O3 form?
Using the standard enthalpy of formation data in Appendix G, determine which bond is stronger: the SF bond in SF4(g) or in SF6(g)?
Explain the decomposition of nitroglycerin in terms of relative bond enthalpies.
Construct a Born–Haber cycle for the formation of the hypotheticalcompound NaCl2, where the sodium ion has a 2+charge (the second ionization energy for sodium is given inTable 7.2). (a) How large would the lattice energy need to befor the formation of NaCl2 to be exothermic? (b) If we wereto estimate the lattice energy of NaCl2 to be roughly equalto that of MgCl2 (2326 kJ/mol from Table 8.1), what valuewould you obtain for the standard enthalpy of formation,ΔHf°, of NaCl2?
One of the following pictures(Figure 1) represents NaCl and one represents MgO. Which is which? (a) is NaCl and (b) is MgO (b) is NaCl and (a) is MgO Which has the larger lattice energy? NaCl MgO
Which set of ionic compounds shows the correct order of increasing lattice energy (lowest-to-highest). (A) NaCl < NaF < KCl < KBr; (B) KBr < KCl < NaCl < NaF; (C) NaF < NaCl < KCl < KBr; (D) KCl < KBr < NaF < NaCl.
(a) Does the lattice energy of an ionic solid increase or decrease(i) as the charges of the ions increase, (ii) as the sizes of the ionsincrease? (b) Arrange the following substances not listed inTable 8.1 according to their expected lattice energies, listing themfrom lowest lattice energy to the highest: MgS, KI, GaN, LiBr.
For each of the following sets of ionic substances, arrange the members in order of increasing lattice energy (smallest first). (a) O MgS O MgCl2 O MgS O MgS O MgCl2 O MgS O MgCl2 O MgCl2 O K2S O K2S O KS O K2S O Nal O Nacl O NaCl O Nacl (b) O NaF O NaF O NaF O NaF O Mgo O AIF3 O Na20 O Mgo O AIF3 O Mgo O MgO O AIF3 O AIF3 O Na20 O Na20 O Na20 (c) O AICI3 O AlCl, O AlCl3 O MgCl2 O AICI3 O MgCl, O MgCl, O MgCl2 O Nacl O NaCl O Nac O Nacl O NaBr O NaBr O NaBr O NaBr
Which compound in each of the following pairs has the larger lattice energy? Note: Mg2+ and Li+ have similar radii; O2– and F– have similar radii. Explain your choices.(a) MgO or MgSe(b) LiF or MgO(c) Li2O or LiCl(d) Li2Se or MgO
Which set of ionic compounds shows the correct order of increasing lattice energy (lowest-to-highest). (A) CaO < MgO < CaCl2 < MgCl2; (B) MgO < MgCl2 < CaO < CaCl2; (C) MgO < CaO < MgCl2 < CaCl2; (D) CaCl2 < MgCl2 < CaO < MgO
(ii) Construct and label a Born-Haber cycle for strontium difluoride, SrF2. Calculate the lattice energy of SrF2 using the following data: First electron affinity of fluoride =–328.0 kJ mol"1 First ionization energy of strontium = 549.0 kJ mol" Second ionization energy of strontium = 1064.0 kJ mol"! Enthalpy of atomization of fluoride = 75.3 kJ mol" Enthalpy of atomization of strontium = 164.0 kJ mol"! Enthalpy of formation of strontium difluoride = -1224.4 kJ mol"!
Use principles of atomic structure to answer each of the following: (1] (a) The radius of the Ca atom is 197 pm; the radius of the Ca2* ion is 99 pm. Account for the difference. (b) The lattice energy of CaO(s) is –3460 kJ/mol; the lattice energy of K20 is –2240 kJ/mol. Account for the difference. (c) Given these ionization values, explain the difference between Ca and K with regard to their first and second ionization energies. Element First lonization Energy (kJ/mol) Second lonization Energy (kJ/mol) K 419 3050 Ca 590 1140 (d) The first ionization energy of Mg is 738 kJ/mol and that of Al is 578 kJ/mol. Account for this difference.