Cristalização de Salol (Salicilato de Fenila)

Observação do crescimento de cristais em um microscópio em tempo real

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

Objetivo

Observar o crescimento em tempo real de cristais de salol em um microscópio, estudando a nucleação, as taxas de crescimento cristalino e o efeito da temperatura na morfologia dos cristais.

Contexto

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.

Avisos de segurança

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

EPI necessário

goggles

Materiais

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

Equipamentos

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

Procedimento

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

Resultados esperados

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).

Limpeza

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

Detalhes

Categoria
Crystallization
Dificuldade
Intermediate (High School)
Duração
30 min
Custo estimado
$10,00
Passos
6
Materiais
3

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Frequently Asked Questions

What is the objective of Cristalização de Salol (Salicilato de Fenila)?
Observar o crescimento em tempo real de cristais de salol em um microscópio, estudando a nucleação, as taxas de crescimento cristalino e o efeito da temperatura na morfologia dos cristais.
How difficult is Cristalização de Salol (Salicilato de Fenila)?
This experiment is rated as Intermediate (High School). It takes approximately 30 minutes to complete.
What safety precautions are needed for Cristalização de Salol (Salicilato de Fenila)?
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 Cristalização de Salol (Salicilato de Fenila)?
The main materials required are: Salol (phenyl salicylate), Microscope slides, Cover slips.
What results should I expect from Cristalização de Salol (Salicilato de Fenila)?
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).