Question

Same halogen atom (-X), increased in the size of the alkyl chain $C{H}_{3}Cl,C{H}_{3}C{H}_{2}Cl,C{H}_3(C{H}_2{)}_{2}Cl,C{H}_3(C{H}_2{)}_{3}Cl$
What is the effect on the boiling point and the density?

• A. Boiling point increases, density increases
• B. Boiling point increases, density decreases
• C. Boiling point decreases, density decreases
• D. Boiling point decreases, density increases

Answer 1

The correct option is A Boiling point increases, density increases

For the same halogen atom, Intermolecular forces of attractions increases as​ molecular size increases.​ So, large amount​ of heat require to break strong intermolecular forces​ and thus boiling point increases.
Here, the order of molecular size is as follows:$C{H}_{3}Cl<C{H}_{3}C{H}_{2}Cl<C{H}_3(C{H}_2{)}_{2}Cl<C{H}_3(C{H}_2{)}_{3}Cl$
Therefore, the boiling point order will be $C{H}_{3}Cl<C{H}_{3}C{H}_{2}Cl<C{H}_3(C{H}_2{)}_{2}Cl<C{H}_3(C{H}_2{)}_{3}Cl$
Increase in number of C and H atoms​ or increase in​ atomic mass of halogen atoms​ increase density of haloalkane, density order will be $C{H}_{3}Cl<C{H}_{3}C{H}_{2}Cl<C{H}_3(C{H}_2{)}_{2}Cl<C{H}_3(C{H}_2{)}_{3}Cl.$