The enthalpy of formation of metal halides primarily correlates with lattice energy, defined as the energy released during solid lattice formation from constituent ions.
• Fluoride (F-): Being the smallest halide ions, fluorides exhibit high lattice energy, leading to the most negative enthalpy of formation with metals.
• Chloride (Cl-): Larger than fluoride, chloride ions possess a lower lattice energy than fluorides but higher than other halides, resulting in a less negative enthalpy of formation.
• Bromide (Br-): Larger than chloride, bromide ions yield an even smaller lattice energy and a proportionally less negative enthalpy of formation.
• Iodide (I-): As the largest halide ions, iodides demonstrate the smallest lattice energy, leading to the least negative enthalpy of formation.
Consequently, the enthalpy of formation, from most to least negative, follows the order: Fluoride > Chloride > Bromide > Iodide.
Consider the following compounds:
(i) CH₃CH₂Br
(ii) CH₃CH₂CH₂Br
(iii) CH₃CH₂CH₂CH₂Br
Arrange the compounds in the increasing order of their boiling points.
Assertion (A): The boiling points of alkyl halides decrease in the order: RI>RBr>RCl>RF.
Reason (R): The boiling points of alkyl chlorides, bromides and iodides are considerably higher than that of the hydrocarbon of comparable molecular mass.
Arrange the following compounds in increasing order of their boiling point: \[ \text{(CH}_3\text{)}_2\text{NH, CH}_3\text{CH}_2\text{NH}_2, \text{CH}_3\text{CH}_2\text{OH} \]