The enthalpy of formation of caesium chloride is -44.28kjmol-1 and enthalpy of sublimation of caesium is +77.66kjmol-1.With other data from other sources calculate the lattice energy of CsCl(s)?
1. Cs(s) ==> Cs(g) ..............dH = 77.66 kJ/mol
2. Cs(s) ==> Cs^+ + e...........dH = look up ionization
3. Cl2(g) ==> 2Cl(g)....................dH = look up Cl-Cl dissociation energy
4. Cl(g) + e ==> Cl^- ...............dH = look up electron affinity
Cs(s) + 1/2 Cl2 ==> CsCl ....dH formation = -44/28 kJ/mol
dHf = 1 + 2 + 3 + 4 + U where U = lattice energy. Solve for U.
I will post a URL that will show you how to do this with NaCl.
//www.sarthaks.com/932021/calculate-the-lattice-energy-of-sodium-chloride-using-born-haber-cycle
Fami
Yes
To calculate the lattice energy of CsCl (sodium chloride), we need to use the Born-Haber cycle, which involves a series of steps to calculate the overall energy change. The lattice energy can be determined by subtracting the sum of all the other energy terms from the overall energy change.
The Born-Haber cycle for CsCl is as follows:
1. Formation of CsCl(s): ΔHf (enthalpy of formation) = -44.28 kJ/mol.
This energy term represents the energy released when one mole of CsCl is formed from its constituent elements in their standard states.
2. Sublimation of Cs (s): ΔHsub (enthalpy of sublimation) = +77.66 kJ/mol.
This energy term represents the energy required to convert one mole of solid Cs into gaseous Cs atoms.
3. Dissociation of Cl2 (g): ΔHdiss (enthalpy of dissociation) = X kJ/mol.
This energy term represents the energy required to convert one mole of Cl2 gas into two moles of Cl atoms.
4. Ionization of Cs (g): ΔHion (enthalpy of ionization) = Y kJ/mol.
This energy term represents the energy required to remove one mole of electrons from one mole of gaseous Cs atoms, forming Cs+ ions.
5. Electron affinity of Cl (g): ΔHea (electron affinity) = Z kJ/mol.
This energy term represents the energy released when one mole of gaseous Cl atoms accepts one mole of electrons, forming Cl- ions.
6. Formation of CsCl (ionic bond formation): ΔHlatt (lattice energy) = ?
The overall energy change in the Born-Haber cycle is zero, so we can write the equation as:
ΔHf + ΔHsub + ΔHdiss + ΔHion + ΔHea + ΔHlatt = 0
Rearranging the equation, we can solve for the lattice energy:
ΔHlatt = - (ΔHf + ΔHsub + ΔHdiss + ΔHion + ΔHea)
To calculate the lattice energy, we need the values of ΔHdiss, ΔHion, and ΔHea from other sources (such as reference books or databases).
Once you have these values, substitute them into the equation above to find the lattice energy of CsCl (s). Make sure to use the appropriate units for each term and ensure that the signs of the values are correctly accounted for.