Benzoik Asidin Yeniden Kristallendirilmesi

Katı bir maddeyi sıcak çözücüde çözüp soğutarak saflaştırma

Crystallization Intermediate (High School) 45 dak ~$10,00

Hedef

Saf olmayan benzoik asidi sıcak su içinde yeniden kristallendirerek saflaştırmak; organik katılar için standart saflaştırma tekniğini göstermek.

Arka Plan

Recrystallization exploits the difference in solubility of a substance at different temperatures. Benzoic acid is very soluble in hot water but nearly insoluble in cold water. By dissolving impure benzoic acid in hot water and cooling slowly, pure crystals form while impurities remain in solution.

Güvenlik Uyarıları

  • Handle hot water and hot glassware with care
  • Benzoic acid dust can irritate airways
  • Use heat-resistant gloves when handling hot flasks

Gerekli KKD

goggles lab_coat

Malzemeler

  • Impure benzoic acid (3 g)
    Mixed with charcoal or sand
  • Distilled water (200 mL)
  • Activated charcoal (0.5 g)
    Optional, for decolorization

Ekipman

250 mL Erlenmeyer flask Hot plate Buchner funnel Filter flask Vacuum pump Melting point apparatus Ice bath Watch glass

Prosedür

1

Weigh 3 g of impure benzoic acid and record the mass. Note the appearance (color, particle size).

3 dak
2

Add the impure sample to 100 mL of distilled water in the Erlenmeyer flask. Heat to boiling while stirring.

8 dak Handle hot flask with care
3

If the solution is colored, add 0.5 g activated charcoal, swirl, and filter hot through fluted filter paper.

5 dak
4

Allow the clear filtrate to cool slowly to room temperature. Do not disturb.

15 dak
5

Cool further in an ice bath to maximize crystal yield.

5 dak
6

Collect the crystals by vacuum filtration. Wash with a small amount of ice-cold water.

5 dak
7

Dry the crystals on a watch glass. Weigh and calculate percent recovery.

3 dak
8

Determine the melting point (pure benzoic acid: 122°C) and compare with the impure sample.

5 dak

Beklenen Sonuçlar

White, needle-like crystals with a sharp melting point at 121-123°C. Typical recovery is 60-80%. The purified crystals should be whiter and have a sharper melting point than the crude material.

Temizlik

Dispose of filtrate down the drain (benzoic acid is food-grade). Rinse glassware. Dispose of charcoal in solid waste.

Ayrıntılar

Kategori
Crystallization
Zorluk
Intermediate (High School)
Süre
45 dak
Tahmini Maliyet
$10,00
Adımlar
8
Malzemeler
3

Daha Fazla Deney

Aşırı Doygunluk ve Anlık Kristallenme 35 min Bakır Sülfat Kristali Büyütme 30 min Bizmut Gökkuşağı Kristali Büyütme 45 min Salol (Fenil Salisilat) Kristallenmesi 30 min Şap Kristali Büyütme 30 min Şeker Kristali Akide Şekeri 25 min Tuz ve Kumun Kademeli Kristallenmesi 35 min

Frequently Asked Questions

What is the objective of Benzoik Asidin Yeniden Kristallendirilmesi?
Saf olmayan benzoik asidi sıcak su içinde yeniden kristallendirerek saflaştırmak; organik katılar için standart saflaştırma tekniğini göstermek.
How difficult is Benzoik Asidin Yeniden Kristallendirilmesi?
This experiment is rated as Intermediate (High School). It takes approximately 45 minutes to complete.
What safety precautions are needed for Benzoik Asidin Yeniden Kristallendirilmesi?
Key safety precautions include: Handle hot water and hot glassware with care; Benzoic acid dust can irritate airways; Use heat-resistant gloves when handling hot flasks.
What materials are needed for Benzoik Asidin Yeniden Kristallendirilmesi?
The main materials required are: Impure benzoic acid, Distilled water, Activated charcoal.
What results should I expect from Benzoik Asidin Yeniden Kristallendirilmesi?
White, needle-like crystals with a sharp melting point at 121-123°C. Typical recovery is 60-80%. The purified crystals should be whiter and have a sharper melting point than the crude material.