alculate the amount of energy released in the formation of one mole of MgSe bonds (not lattice energy). The radius of the magnesium ion is 0.65 Å, and the radius of the selenide ion is 1.98 Å. Note that 1Å=10−10m
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To calculate the amount of energy released in the formation of one mole of MgSe bonds, we need to use the concept of the Born-Haber cycle. The Born-Haber cycle is a series of steps that allows us to calculate the energy changes involved in the formation of an ionic compound from its constituent elements.
The formation of one mole of MgSe involves several steps:
1. Ionization of magnesium:
Mg (s) ⟶ Mg+ (g) + e-
The energy required for this step is the first ionization energy of magnesium (IE1).
2. Ionization of selenium:
1/2 Se2 (g) ⟶ Se (g)
The energy required for this step is the electron affinity of selenium (EA).
3. Sublimation of magnesium:
Mg (s) ⟶ Mg (g)
The energy required for this step is the sublimation energy of magnesium (ΔHsub).
4. Dissociation of diatomic selenium:
1/2 Se2 (g) ⟶ Se (g)
The energy required for this step is the bond dissociation energy of selenium (D).
5. Formation of MgSe:
Mg+ (g) + Se (g) ⟶ MgSe (s)
The energy released in this step is the lattice energy of MgSe (LE).
The overall energy change in the formation of one mole of MgSe is given by:
ΔHf°(MgSe) = IE1 + EA + ΔHsub + D + LE
Now, let's find the values for each of these energies:
1. First ionization energy of magnesium (IE1):
This information can be found in a reference table or chemical database. Let's assume it is 737 kJ/mol.
2. Electron affinity of selenium (EA):
Similarly, this information can be found in a reference table or chemical database. Let's assume it is -195 kJ/mol.
3. Sublimation energy of magnesium (ΔHsub):
Again, this information can be found in a reference table or chemical database. Let's assume it is 150 kJ/mol.
4. Bond dissociation energy of selenium (D):
This value can also be found in a reference table or chemical database. Let's assume it is 180 kJ/mol.
5. Lattice energy of MgSe (LE):
Unfortunately, we don't have the lattice energy value given. To calculate it, we would need to know the charges on the ions involved and their distances apart. The given information in the question only provides the radii of the ions, which is not sufficient to calculate the lattice energy.
Therefore, without the value for the lattice energy, we cannot calculate the amount of energy released in the formation of one mole of MgSe bonds.