born haber prob 2011
TRANSCRIPT
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Chem 1711 Born-Haber Cycle, Practice Problems
1. Given the following information for magnesium, oxygen, and magnesium oxide calculate the second electron gain
enthalpy for oxygen {i.e. for O(g) + e!O2(g)}.
for Mg (s), !Hsub= +148 kJ/mol bond dissociation energy for O2= +499 kJ/mol
1stionization energy for Mg = +738 kJ/mol 1stelectron gain enthalpy for O = 141 kJ/mol
2ndionization energy for Mg = +1450 kJ/mol for MgO (s), lattice energy = +3890 kJ/mol
for MgO (s), enthalpy of formation = 602 kJ/mol
2. Consider an ionic compound MX2where M is a metal that forms a cation of +2 charge, and X is a nonmetal that forms an
anion of 1 charge. A Born-Haber cycle for MX2is given below. Each step in this cycle has been assigned a number
(1 7).
M (s) + X2(g)
MX2(s)
M2+(g) + 2 X-(g)
M (g)
M+(g)
2 X (g)
1
2
3
4
5
6
7
a. Identify one step (1 - 7) that is endothermic as written. ______________
b. Which step (1 - 7) corresponds to !Hosub? _____________
c. Which step (1 - 7) corresponds to !Hof? _____________
d. Use the following energy values to calculate the lattice energy (in kJ/mol) for MX2.
!Hosub= 296 kJ/mol; !Hof= -421 kJ/mol; 1
stionization energy = 378 kJ/mol;
2ndionization energy = 555 kJ/mol; bond dissociation enthalpy = 310 kJ/mol;
electron affinity = -427 kJ/mol.
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Born'Haber
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Practice
Problerns
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