Which one has more lattice energy, Na3N or NaF ?

In case of Na3F and NaF molecules, cations are same but anions are different [ N3-, F- ] .It is experimentally proved that the radius of N3-ions is greater than F-ion.

Now, lattice energy is directly proportional to the multiple of ionic charge and inversely proportional to the radius of cation and anion.

So, the lattice energy ofNaF should be greater than that of Na 3N compound. But, actually the order of lattice energy of NaF and Na3N compound is reversed.

Because, in calculation of lattice energy of ionic compounds , the extent of ionic charge is more effective than ionic radius.

Since the is ionic charge of N3-ion greater than F -, hence Na3N compound has high lattice energy than NaF .

The value of lattice energy of Na3N is -4422 kj/mole and that of NaF is -923 Kj/mole.

Calculation of lattice energy of Na3N compound.

of Lattice energy Na3N compound can be calculated indirectly by applying Born-Haber cycle. The Born-Haber cycle of Na3N compound is shown below.

According to the Born-Haber cycle of Na3N compound, we can write a relation amongenthalpy of formation of Na3N,electron affinity and bond dissociation of nitrogen, ionization energy and sublimation energy of sodium and lattice energy released are,

ΔHf=S+ [3 x I.E] + [ I.E1 + I.E2 + I.E3 ] + ½ D + U

Or,- 20= 322+ 1488+2120+472+ U

Or, U =- 4422 Kj/mole

Therefore, the lattice energy of Na3N compound is -4422 kJ/mole.

Which has more lattice energy, NaCl or NaF ?

In case of NaCl and NaF molecules, cations are same but anions are different [ Cl -, F -] .The radius of halide ions increase from top to bottom along a group.

From the experimental data we know that the radius of chloride [ Cl-] ion is greater than fluoride ion [ F -] .

is Now, lattice energy directly proportional to the multiple of ionic charge and inversely proportional to the radius of cation and anion.

Consequently, NaCl and NaF molecules are LiF has highest lattice energy. The value of lattice energy of , -785 kJ/mole and -923 Kj/mole respectively.

Which one has more lattice energy, Na3N or NaF ?

Which has more lattice energy, NaCl or NaF ?

Calculation of lattice energy of Na3N compound.

Originally published at https://chemisfast.blogspot.com.