बेंजोइक अम्ल का पुनःक्रिस्टलीकरण

गर्म विलायक में घोलकर और ठंडा करके एक ठोस को शुद्ध करना

Crystallization Intermediate (High School) 45 मिनट ~$10.00

उद्देश्य

जैविक ठोस पदार्थों के लिए मानक शुद्धिकरण तकनीक प्रदर्शित करते हुए, गर्म पानी से पुनःक्रिस्टलीकरण द्वारा अशुद्ध बेंजोइक अम्ल को शुद्ध करें।

पृष्ठभूमि

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.

सुरक्षा चेतावनियाँ

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

आवश्यक PPE

goggles lab_coat

सामग्री

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

उपकरण

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

प्रक्रिया

1

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

3 मिनट
2

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

8 मिनट 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 मिनट
4

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

15 मिनट
5

Cool further in an ice bath to maximize crystal yield.

5 मिनट
6

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

5 मिनट
7

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

3 मिनट
8

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

5 मिनट

अपेक्षित परिणाम

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.

सफाई

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

विवरण

श्रेणी
Crystallization
कठिनाई
Intermediate (High School)
अवधि
45 मिनट
अनुमानित लागत
$10.00
चरण
8
सामग्री
3

अधिक प्रयोग

अतिसंतृप्ति और तात्कालिक क्रिस्टलीकरण 35 min कॉपर सल्फेट क्रिस्टल उगाना 30 min चीनी क्रिस्टल रॉक कैंडी 25 min नमक और रेत का खंडित क्रिस्टलीकरण 35 min फिटकरी क्रिस्टल उगाना 30 min बिस्मथ इंद्रधनुष क्रिस्टल उगाना 45 min सैलोल (फेनाइल सैलिसिलेट) का क्रिस्टलीकरण 30 min

Frequently Asked Questions

What is the objective of बेंजोइक अम्ल का पुनःक्रिस्टलीकरण?
जैविक ठोस पदार्थों के लिए मानक शुद्धिकरण तकनीक प्रदर्शित करते हुए, गर्म पानी से पुनःक्रिस्टलीकरण द्वारा अशुद्ध बेंजोइक अम्ल को शुद्ध करें।
How difficult is बेंजोइक अम्ल का पुनःक्रिस्टलीकरण?
This experiment is rated as Intermediate (High School). It takes approximately 45 minutes to complete.
What safety precautions are needed for बेंजोइक अम्ल का पुनःक्रिस्टलीकरण?
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 बेंजोइक अम्ल का पुनःक्रिस्टलीकरण?
The main materials required are: Impure benzoic acid, Distilled water, Activated charcoal.
What results should I expect from बेंजोइक अम्ल का पुनःक्रिस्टलीकरण?
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.