JEE Main202313 Apr 2023Evening ShiftChemistryClassification of Elements and Periodicity in PropertiesActual
. Identify the correct order of standard enthalpy of formation of sodium halides.
Options
- ANaI   <   NaBr   <   NaF   <   NaCl
- BNaI   <   NaBr   <   NaCl   <   NaF
- CNaF   <   NaCl   <   NaBr   <   NaI
- DNaCl   <   NaF   <   NaBr   <   NaI
Correct answer
B. NaI   <   NaBr   <   NaCl   <   NaF
Step-by-step solution
The lattice energy of an ionic compound is the energy required to separate one mole of the compound into its constituent ions in the gas phase. Lattice energy ∝ 1 r + + r - The lattice energy is inversely proportional to the sum of the ionic radii r + + r - of the ions involved. When the size of the ions increases, the distance between them also increases, leading to a decrease in the attractive forces between the ions and a decrease in the lattice energy. Therefore, if the size of the ions increases, the lat