Cristallisation du Salol (Salicylate de Phényle)

Observation en temps réel de la croissance de cristaux sous microscope

Crystallization Intermediate (High School) 30 min ~$10,00

Objectif

Observer la croissance en temps réel de cristaux de salol sous microscope, en étudiant la nucléation, les vitesses de croissance cristalline et l'effet de la température sur la morphologie des cristaux.

Contexte

Salol (phenyl salicylate) has a melting point of 43°C, making it perfect for observing crystallization under a microscope in real time. It can be melted on a microscope slide and watched as it crystallizes, with the crystal fronts growing visibly. Supercooling is easily demonstrated.

Avertissements de sécurité

  • Salol can irritate skin — wash hands after handling
  • Handle microscope slides carefully — breakage risk
  • Do not overheat salol (decomposes above 70°C)

EPI requis

goggles

Matériaux

  • Salol (phenyl salicylate) (2 g)
    Melting point 43°C
  • Microscope slides (3)
  • Cover slips (3)

Équipement

Microscope (at least 40x) Hot plate or warm water bath Tweezers Timer

Procédure

1

Place a small amount of salol on a microscope slide. Warm gently on the hot plate until the salol melts (43°C). Place a cover slip on top.

5 min Do not overheat — decomposes above 70°C
2

Place the slide on the microscope stage. Focus at low magnification (40x). Allow to cool.

3 min
3

Watch for nucleation points — small bright spots where crystal growth begins.

5 min
4

Observe the crystal growth fronts expanding across the field of view. Time the growth rate.

5 min
5

Touch a cold metal object to one edge of the slide to create a temperature gradient. Observe how crystal morphology changes with cooling rate.

5 min
6

Draw or photograph the crystal patterns. Note the needle-like or fan-shaped morphology.

5 min

Résultats attendus

Needle-like or fan-shaped crystal fronts should be visible growing across the field of view in real time. Faster cooling produces finer needles; slower cooling produces larger, more regular crystals. Supercooling may be observed (liquid persists below 43°C until nucleation occurs).

Nettoyage

Allow slides to cool completely. Scrape off salol and dispose in solid waste. Clean slides with ethanol.

Détails

Catégorie
Crystallization
Difficulté
Intermediate (High School)
Durée
30 min
Coût estimé
$10,00
Étapes
6
Matériaux
3

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Frequently Asked Questions

What is the objective of Cristallisation du Salol (Salicylate de Phényle)?
Observer la croissance en temps réel de cristaux de salol sous microscope, en étudiant la nucléation, les vitesses de croissance cristalline et l'effet de la température sur la morphologie des cristaux.
How difficult is Cristallisation du Salol (Salicylate de Phényle)?
This experiment is rated as Intermediate (High School). It takes approximately 30 minutes to complete.
What safety precautions are needed for Cristallisation du Salol (Salicylate de Phényle)?
Key safety precautions include: Salol can irritate skin — wash hands after handling; Handle microscope slides carefully — breakage risk; Do not overheat salol (decomposes above 70°C).
What materials are needed for Cristallisation du Salol (Salicylate de Phényle)?
The main materials required are: Salol (phenyl salicylate), Microscope slides, Cover slips.
What results should I expect from Cristallisation du Salol (Salicylate de Phényle)?
Needle-like or fan-shaped crystal fronts should be visible growing across the field of view in real time. Faster cooling produces finer needles; slower cooling produces larger, more regular crystals. Supercooling may be observed (liquid persists below 43°C until nucleation occurs).