Question

Sodium chloride has a lattice energy of - 787 kJ/mol. Computational analysis of a hypothetical salt XY indicates that X^3+ has the same radius as the sodium ion and Y^3- has the same radius as the chloride ion. Estimate the lattice energy of XY.

Answer #1

Born and Lande presented the following model for lattice energy:

*E*=−*N*_{A}*M**z*^{+}*z*^{−}*e*^{2}/4*π**ϵ*_{o}*r*_{o}
(1−1/*n*)

In this equation, N_{A} is Avogadro's constant; M is the
Madelung constant, which depends on the crystal geometry;
z^{+} is the charge number of the cation; z^{-} is
the charge number of the anion; e is the elementary charge of the
electron; n is the Born exponent, a characteristic of the
compressibility of the solid; *ϵ*_{o} is
the permittivity of free space; and r_{0} is the distance
to the closest ion.

This model emphasizes two main factors that contribute to the lattice energy of an ionic solid: the charge on the ions, and the radius, or size, of the ions. The effect of those factors is:

- as the charge of the ions increases, the lattice energy increases
- as the size of the ions increases, the lattice energy decreases
- Therefore, the lattice energy for the hypothetical salt XY may be nearly 9 times to that of NaCl assuming all others factors in the above equation are same as NaCl
- -787x3x3 = 7083 KJ/mol

1. A compound composed of only carbon and chlorine is 85.5%
chlorine by mass and its molar mass is 165.82 g/mol. Propose a
Lewis structure for the compound.
2. RbI has a lattice energy -617 kJ/mol . Consider a
hypothetical salt XY. X^3+ has the same radius of Rb^+ and Y^3− has
the same radius as I^−. Estimate the lattice energy of XY

Define lattice energy (ΔH^o lattice). The lattice energies (ΔH^o
lattice) for sodium chloride and potassium chloride are -788 kJ
and -717 kJ, respectively. Based on Coulomb’s Law, briefly explain
why the lattice energy for potassium chloride is less than the
lattice energy for sodium chloride.

Sodium nitrate has a lattice energy of -2.48 x 10^2 kJ/mol, and
a heat of hydration of -234 kJ/mol.
Determine how much heat is evolved or absorbed when 16.5 g of
sodium nitrate completely dissolves in water?

Sodium hydroxide (NaOH) has a lattice energy of -887 kJ/mol and
a heat of hydration of -932 kJ/mol. How much solution could be
heated to boiling by the heat evolved by the dissolution of 28.0 g
of NaOH? (For the solution, assume a heat capacity of 4.0 J/g⋅∘C,
an initial temperature of 25.0 ∘C, a boiling point of 100.0 ∘C, and
a density of 1.05 g/mL.)

Construct a Born-Haber cycle for the formation of the
hypothetical compound NaCl2, where the sodium ion has a 2+ charge
(the 2nd ionization energy for sodium is given in Table 7.2 in the
textbook).
Part B
If we were to estimate the lattice energy of NaCl2 to be roughly
equal to that of MgCl2 (2326 kJ/mol from Table 8.2 in the
textbook), what value would you obtain for the standard enthalpy of
formation, ΔH∘f, of NaCl2?
Express your answer using...

Consider two hypothetical elements, X and Z. Element X has an
electron affinity of 300 kj/mol and element Z has an electrona
ffinity of 75 kj/mol. If you have an X- ion and a Z- ion from which
ion would it require more energy to remove an electron? Explain. I
think it's X but can someone give me a well formulated explanantion
or explanations. Thank you!

Potassium perchlorate (KClO4) has a lattice energy of -599
kJ/mol and a heat of hydration of -548 kJ/mol.
A) Find the heat of solution for potassium perchlorate when 10.2
g of potassium perchlorate is dissolved with enough water to make
118.5 mLof solution.

Potassium nitrate has a lattice energy of -163.8 kcal/mol and a
heat of hydration of -155.5 kcal/mol. How much potassium nitrate
has to dissolve in water to absorb 102 kJ of heat? There are 4.184
kJ/kcal. Also note the answer is to be reported in kg.

Potassium nitrate has a lattice energy of -163.8 kcal/mol and a
heat of hydration of -155.5 kcal/mol.
Question:
How much potassium nitrate has to dissolve in water to absorb
109 kJ of heat? There are 4.184 kJ/kcal. Also note the answer is to
be reported in kg.

Potassium nitrate has a lattice energy of -163.8 kcal/mol and a
heat of hydration of -155.5 kcal/mol
1.How much potassium nitrate has to dissolve in water to absorb
107 kJ of heat? There are 4.184 kJ/kcal. Also note the answer is to
be reported in kg.

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