Physical Properties of Haloalkanes & Haloarenes

Colour & Smell 🌈👃

• Pure alkyl halides look colourless, but bromides and iodides pick up colour when you leave them in light.✨ :contentReference[oaicite:0]{index=0}
• Many volatile halogen compounds greet you with a pleasant, sweet smell.😊 :contentReference[oaicite:1]{index=1}

State at Room Temperature 🌡️

• \(\mathrm{CH_3Cl}\), \(\mathrm{CH_3Br}\), \(\mathrm{C_2H_5Cl}\) and some chlorofluoromethanes stay gaseous around 25 °C. :contentReference[oaicite:2]{index=2}
• Heavier cousins shift to liquids or even solids as molecules grow larger. :contentReference[oaicite:3]{index=3}

Boiling & Melting Points 🔥❄️

Because these molecules are polar and hefty, they stick together more tightly than hydrocarbons, so temperatures have to climb higher to pull them apart. :contentReference[oaicite:4]{index=4}

• For one alkyl group, boiling points fall in the order
  \(\mathrm{RI} > \mathrm{RBr} > \mathrm{RCl} > \mathrm{RF}\). 💡 :contentReference[oaicite:5]{index=5}
• Bigger molecules (more electrons) hold on tighter, so their boiling points shoot up. 📈 :contentReference[oaicite:6]{index=6}
• More branching chops the boiling point; 2-bromo-2-methylpropane sits lowest among its three isomers. 🌿 → 🔥↓ :contentReference[oaicite:7]{index=7}
• Isomeric dihalobenzenes boil at almost the same point, yet para-isomers melt highest because their neat shape packs better into a crystal. ❄️💎 :contentReference[oaicite:8]{index=8}

Solubility 💧

• Haloalkanes hardly dissolve in water—you must break strong hydrogen bonds, but you do not get equally strong new ones. :contentReference[oaicite:9]{index=9}
• They mix happily with organic solvents where the old and new attractions match in strength. 🤝 :contentReference[oaicite:10]{index=10}

Density ⚖️

Density climbs as you add heavier or extra halogen atoms. Bromo-, iodo- and many polychloro compounds sink below water. 🌊↓ :contentReference[oaicite:11]{index=11}

👉 Notice how each extra or heavier halogen pushes the number up! :contentReference[oaicite:12]{index=12}

Quick Practice 🎯

Put these in rising order of boiling point:

1. Chloromethane
2. Bromomethane
3. Dibromomethane
4. Bromoform

Tip: Heavier and more polar means hotter! 🔥

High-Yield NEET Takeaways 🚀

1. Order of boiling points for one alkyl group:
   \(\mathrm{RI} > \mathrm{RBr} > \mathrm{RCl} > \mathrm{RF}\).
2. Boiling point falls as branching increases.
3. Haloalkanes barely dissolve in water but blend well with organic solvents.
4. Bromo, iodo and heavily chlorinated compounds are denser than water—expect them as the lower layer in a separating funnel.
5. Bromides and iodides gain colour in light—an easy lab clue for questions.