Winter in the glass

Frost appears on a pine twig when it is heated!

Scientific name: Naphthalene is sublimed under heating and recrystallized again under cooling.

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Cooling Naphthalene Experiment

Возгонка нафталина

Зима в стакане - красивый новогодний химический опыт!

by Thoisoi

Safety

Wear eye protection and gloves. Work in a well-ventilated room or outdoors.

Always follow general safety recommendations. Please note that conducting chemistry experiments you must comply with the relevant legal procedures in your country.

Reaction formula

C10H8 (solid) -[heating]→ C10H8 (gas) -[cooling]→ C10H8 (solid)

C6H5COOH (solid) -[heating]→ C6H5COOH (gas) -[cooling]→ C6H5COOH (solid)

Step-by-step instruction

  1. Put some naphthalene into the beaker. Benzoic acid can be used instead of naphthalene.
  2. Clamp the beaker to a stand. Place the gas burner under it.
  3. Place a small pine or spruce twig into the beaker.
  4. Put the watch glass on top of the beaker.
  5. Heat the beaker with a gas burner.
  6. Naphthalene sublimes and recrystallizes on pine needles.

Scientific background

In this experiment solid naphthalene is vaporized without passing through a liquid state. The process of solid phase conversion directly to the gas phase is called sublimation. Each substance at given pressure and temperature possess one of three main states: solid, liquid or gaseous. Temperature or pressure change can lead to appropriate phase transition. The dependency of the substance state on temperature and pressure could be represented as a phase diagram. A phase diagram is type of chart describing the conditions at which distinct phases can occur in equilibrium. A typical phase diagram has “y-like” shape. On a phase diagram one can find a special point – triple point – at which solid, vapor and liquid can coexist in thermodynamic equilibrium. Sublimation takes place at temperatures and pressures below the substance triple point. When naphthalene crystals are heated, the temperature increases and we shift along the abscissa axis from the area of phase diagram corresponding to solid state to area corresponding to gas. Cooling causes the reverse transition. When naphthalene vapors reach pine needles it cools down and recrystallizes. The reverse process of direct solid phase formation from vapors is called desublimation or decomposition.

Danger:
Coolness:
Difficulty:

Published on 23 April 2015

  • Fire
  • Heating with fire
  • Explosion
  • Poisoned gas
  • Organic
  • Electricity
  • Solution
  • Oxidation reduction
  • Color change
  • Precipitate
  • Gassing
  • Catalyst