? ? a) Give a definition of lattice energy. Does your definition mean that the associated enthalpy

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a) Give a definition of lattice energy. Does your definition mean that the associated enthalpy of reaction will be positive or negative? (b) Use the Born-Landé equation to calculate a value for the lattice energy of KBr, for which ro = 328 pm. KBr adopts an NaCl structure; other data may be found in Tables 6.3 and 6.4. = for a the owly and unc- writ- ture win the ung fore 50- stri- lattice fr AU= where B=repulsion coefficient n-Born exponent Values of the Born exponent (Table 6.3) can be evaluated from compressibility data and depend on the electronic Table 6.3 Values of the Born exponent, n, given for ionic compound MX in terms of the electronic configuration of the ions [MI[X]. The value of n for an ionic compound is determined by averaging the component values, e.g. for MgO, n = 7; for Li 20 5+9 2 11= = 7. Electronic configuration of the ions in an ionic compound MX [He][He] [Ne][Ne] [Ar][Ar], or [3d¹0][Ar] [Kr][Kr] or [4d¹0][Kr] [Xe][Xe] or [5d'][Xe] Examples of ions n (no units) H, Lit F, 02, Na+, Mg²+ 7 CI, S², K+, Ca²+, Cut 9 Br, Rb, Sr²+, Ag+ 10 I,Cs*, Ba2+, Au* 12 5 ta e Table 6.4 Madelung constants, A, for selected structure types. Values of A are numerical and have no units. Structure type Sodium chloride (NaCl) Caesium chloride (CsCl) Wurtzite (a-ZnS) Zinc blende (ß-ZnS) Fluorite (CaF2) Rutile (TiO₂) Cadmium iodide (CdI₂) A 1.7476 1.7627 1.6413 1.6381 2.5194 2.408 2.355* + For these structures, the value depends slightly on the lattice parameters for the unit cell. a) Give a definition of lattice energy. Does your definition mean that the associated enthalpy of reaction will be positive or negative? (b) Use the Born-Landé equation to calculate a value for the lattice energy of KBr, for which ro = 328 pm. KBr adopts an NaCl structure; other data may be found in Tables 6.3 and 6.4. = for a the owly and unc- writ- ture win the ung fore 50- stri- lattice fr AU= where B=repulsion coefficient n-Born exponent Values of the Born exponent (Table 6.3) can be evaluated from compressibility data and depend on the electronic Table 6.3 Values of the Born exponent, n, given for ionic compound MX in terms of the electronic configuration of the ions [MI[X]. The value of n for an ionic compound is determined by averaging the component values, e.g. for MgO, n = 7; for Li 20 5+9 2 11= = 7. Electronic configuration of the ions in an ionic compound MX [He][He] [Ne][Ne] [Ar][Ar], or [3d¹0][Ar] [Kr][Kr] or [4d¹0][Kr] [Xe][Xe] or [5d'][Xe] Examples of ions n (no units) H, Lit F, 02, Na+, Mg²+ 7 CI, S², K+, Ca²+, Cut 9 Br, Rb, Sr²+, Ag+ 10 I,Cs*, Ba2+, Au* 12 5 ta e Table 6.4 Madelung constants, A, for selected structure types. Values of A are numerical and have no units. Structure type Sodium chloride (NaCl) Caesium chloride (CsCl) Wurtzite (a-ZnS) Zinc blende (ß-ZnS) Fluorite (CaF2) Rutile (TiO₂) Cadmium iodide (CdI₂) A 1.7476 1.7627 1.6413 1.6381 2.5194 2.408 2.355* + For these structures, the value depends slightly on the lattice parameters for the unit cell.

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Lattice energy is a measure of the strength of the ionic bonds in an ionic compound Lattice energy c... View the full answer