SUMMARY
The enthalpy of formation (ΔHf) for sodium chloride (NaCl) is less negative than that for potassium chloride (KCl) due to the differences in ionic size and lattice energy. While Na+ has a smaller ionic radius than K+, resulting in stronger electrostatic attractions with Cl-, the lattice energy of KCl is significantly higher due to the larger size of K+, which allows for a more stable lattice structure. Consequently, the overall energy released during the formation of KCl is greater, leading to a more negative ΔHf compared to NaCl.
PREREQUISITES
- Understanding of ionic bonding and lattice energy
- Knowledge of enthalpy of formation concepts
- Familiarity with periodic trends in ionic sizes
- Basic thermodynamics principles
NEXT STEPS
- Research the concept of lattice energy and its calculation methods
- Study the periodic trends in ionic radii and their effects on ionic compounds
- Explore the relationship between ionic size and enthalpy of formation
- Learn about the Born-Haber cycle for calculating lattice energies
USEFUL FOR
Chemistry students, educators, and anyone studying thermodynamics and ionic compounds will benefit from this discussion.