Lattice enthalpy is a measure of the strength of the forces between the ions in an ionic solid.
Write one equation to represent each the following changes:
Atomisation of sodium
Second ionisation energy of magnesium
First electron affinity of chlorine
Complete Table 1 for the following Born-Harber cycle for formation of potassium fluoride shown in Figure 1. Include equations and state symbols in your answer.
Figure 1
Table 1
Step |
Name of the Enthalpy Change |
1 |
|
2 |
Atomisation of potassium |
3 |
|
4 |
First ionisation energy of potassium |
5 |
|
6 |
Lattice enthalpy of formation |
The enthalpy of lattice formation of potassium fluoride and caesium fluoride is -830 kJ mol-1 and -730 kJ mol-1 respectively.
Explain why the enthalpy of lattice formation is more exothermic for potassium fluoride.
Use the data in Table 2 to calculate the enthalpy of solution of potassium fluoride.
Table 2
ΔHӨlattKF (kJ mol-1) |
+830 |
ΔHӨhydK+ (kJ mol-1) |
-351 |
ΔHӨhydF- (kJ mol-1) |
-504 |
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