2006-10-10 01:52:34 · 6 answers · asked by ajay v 1 in Education & Reference ➔ Home Schooling
The Lattice energy, U, is the amount of energy requried to separate a mole of the ... Madelung Energy discuss further the lattice energy of ionic crystals. ...
An estimate of the strength of the bonds in an ionic compound can be obtained by measuring the lattice energy of the compound, which is the energy given off ...
Example: The lattice energy of NaCl is the energy given off when Na+ and Cl- ... The lattice energy of NaCl, for example, is 787.3 kJ/mol, which is only ...
Lattice Energy
Lattice Energies and the Strength of the Ionic Bond Lattice Energies and Solubility
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Lattice Energies and the Strength of the Ionic Bond
The force of attraction between oppositely charged particles is directly proportional to the product of the charges on the two objects (q1 and q2) and inversely proportional to the square of the distance between the objects (r2).
The strength of the bond between the ions of opposite charge in an ionic compound therefore depends on the charges on the ions and the distance between the centers of the ions when they pack to form a crystal.
An estimate of the strength of the bonds in an ionic compound can be obtained by measuring the lattice energy of the compound, which is the energy given off when oppositely charged ions in the gas phase come together to form a solid.
Example: The lattice energy of NaCl is the energy given off when Na+ and Cl- ions in the gas phase come together to form the lattice of alternating Na+ and Cl- ions in the NaCl crystal shown in the figure below.
Na+(g) + Cl-(g) NaCl(s) Ho = -787.3 kJ/mol
The lattice energies of ionic compounds are relatively large. The lattice energy of NaCl, for example, is 787.3 kJ/mol, which is only slightly less than the energy given off when natural gas burns.
The bond between ions of opposite charge is strongest when the ions are small.
The lattice energies for the alkali metal halides is therefore largest for LiF and smallest for CsI, as shown in the table below.
Lattice Energies of Alkali Metals Halides (kJ/mol)
F- Cl- Br- I-
Li+ 1036 853 807 757
Na+ 923 787 747 704
K+ 821 715 682 649
Rb+ 785 689 660 630
Cs+ 740 659 631 604
The ionic bond should also become stronger as the charge on the ions becomes larger. The data in the table below show that the lattice energies for salts of the OH- and O2- ions increase rapidly as the charge on the ion becomes larger.
Lattice Energies of Salts of the OH- and O2- Ions (kJ/mol)
OH- O2-
Na+ 900 2481
Mg2+ 3006 3791
Al3+ 5627 15,916
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Lattice Energies and Solubility
When a salt, such as NaCl dissolves in water, the crystals disappear on the macroscopic scale. On the atomic scale, the Na+ and Cl- ions in the crystal are released into solution.
NaCl(s) H2O Na+(aq) + Cl-(aq)
The lattice energy of a salt therefore gives a rough indication of the solubility of the salt in water because it reflects the energy needed to separate the positive and negative ions in a salt.
Sodium and potassium salts are soluble in water because they have relatively small lattice energies. Magnesium and aluminum salts are often much less soluble because it takes more energy to separate the positive and negative ions in these salts. NaOH, for example, is very soluble in water (420 g/L), but Mg(OH)2 dissolves in water only to the extent of 0.009 g/L, and Al(OH)3 is essentially insoluble in water.
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2006-10-10 03:01:52 · answer #1 · answered by im4friend 2 · 0⤊ 3⤋
Lattice energy can be defined two ways. The value is the same but there is a difference in sign.
1. The energy needed to break apart 1 mole of an ionic solid compound into their ions (in gaseous form). This is a positive energy.
2. The energy released when 1 mole of ions (in gaseous forms) combine back to form solid ionic compounds. This is a negative energy since energy is released.
Hydration energy is kind of similar to lattice energy and can be defined as the energy released when water molecules break apart an ionic compound. The difference is that this involves water.
Overall, the relationship between lattice energy and hydration energy is: H_hydration = H_lattice(negative) + H_solv
2014-05-05 13:33:06 · answer #2 · answered by Charlie 2 · 0⤊ 0⤋
Energy Of Hydration
2017-01-01 07:50:12 · answer #3 · answered by rhoat 4 · 0⤊ 0⤋
Hydration Energy
2016-09-29 01:23:55 · answer #4 · answered by quesinberry 4 · 0⤊ 0⤋
The lattice energy of an ionic solid is the amount of energy given off per number (moles) of ions when the oppositely charged ions in the gas phase come together to form a solid. It is used to estimate the strength of bonds in an ionic compound.
What might change the lattice energy is the ionic charge and the ionic radius. It is the energy required to separate (or form) completely the ions in an ionic solid
Calculation
Lattice energy is the energy change when one mole of an ionic compound is converted to gaseous ions.
eg.
NaCl (s) → Na+ (g) + Cl- (g) Energy change = Lattice Energy
Lattice energy is the energy required to completely separate a mole of Ionic solid compound into its gaseous Ions.
It can also be a measurement of the strength of the bonds of an Ionic compound. Lattice energy is higher in an ionic compound with Ions of higher charge, and between Ions with smaller atomic radii.
The potential energy of two interacting Ions [Lattice Energy] is given by the equation: E = k (Q¹Q²)/d Where k is a constant, 8.99 x 10^9 J-m/C^2, d is the distance between the centers of the Ions, and the Q's are the charges on the Ions.[1]
2006-10-10 02:01:36 · answer #5 · answered by rockinsaint 2 · 0⤊ 2⤋
1. I don't know where you're going to get a neon light... 5. Cellulose? A chip of wood. 9. Ethanol alcohol 11. A drop of bleach -- the halogen is chlorine
2016-03-17 04:27:01 · answer #6 · answered by Anonymous · 0⤊ 0⤋