📖 Theory & Concepts ▼

Melting & Boiling Points

Property Melting Point Boiling Point
Definition Solid → Liquid Liquid → Gas
Apparatus Thiele tube, capillary Reflux setup, thermometer
Observable Solid disappears Continuous bubbling

Pure compounds have sharp, narrow melting/boiling ranges. Impurities broaden the range.

Common Compounds

  • Benzoic Acid: MP = 122.4°C (sharp range indicates purity)
  • Naphthalene: MP = 80.2°C (used as moth repellent)
  • Ethanol: BP = 78.3°C (lower than water)
  • Acetone: BP = 56.1°C (volatile solvent)
Did you know? Pure water has a boiling point of exactly 100°C at 1 atm - this is used to calibrate thermometers!

🎯 Objectives

  • • Observe phase changes in equilibrium.
  • • Identify purity via temperature range.

🧪 Procedure

1. Select MP or BP mode.

2. Choose a compound from the dropdown below.

3. Use High Heat to reach 10°C below expected range.

4. Switch to Low Heat for precise determination.

Tip: heat quickly to about 10°C below where you expect the change, then switch to Low Heat so the thermometer keeps pace with the sample.
⚠️ Safety
  • Hot liquid paraffin & Thiele tube reach high temperatures — heat only the bend, never point the open end at anyone, let it cool before handling.
  • Ethanol and acetone are highly flammable — keep their vapours away from the flame; use tiny amounts and good ventilation.
  • Naphthalene vapour is harmful — avoid inhaling it.
  • Mercury thermometer is toxic if broken — handle gently; report any breakage.
  • Wear goggles; hot glass looks exactly like cold glass.
Action Required
25.0°C

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🔮 Predict First

Observation Log
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