안식향산 재결정 정제

뜨거운 용매에 녹인 후 냉각하여 고체 정제하기

Crystallization Intermediate (High School) 45 분 ~$10.00

목표

뜨거운 물에서 재결정으로 불순한 안식향산을 정제하고, 유기 고체의 표준 정제 기술을 실증한다.

배경

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.

안전 경고

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

필수 개인 보호 장비

goggles lab_coat

재료

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

장비

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

실험 절차

1

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

3 분
2

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

8 분 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 분
4

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

15 분
5

Cool further in an ice bath to maximize crystal yield.

5 분
6

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

5 분
7

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

3 분
8

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

5 분

예상 결과

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.

정리

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

세부 정보

카테고리
Crystallization
난이도
Intermediate (High School)
소요 시간
45 분
예상 비용
$10.00
단계
8
재료
3

더 많은 실험

비스무트 무지개빛 결정 키우기 45 min 과포화와 순간 결정화 35 min 황산구리 결정 키우기 30 min 소금과 모래의 분별 결정화 35 min 명반 결정 키우기 30 min 설탕 결정(락캔디) 25 min 살롤(살리실산페닐) 결정화 30 min

Frequently Asked Questions

What is the objective of 안식향산 재결정 정제?
뜨거운 물에서 재결정으로 불순한 안식향산을 정제하고, 유기 고체의 표준 정제 기술을 실증한다.
How difficult is 안식향산 재결정 정제?
This experiment is rated as Intermediate (High School). It takes approximately 45 minutes to complete.
What safety precautions are needed for 안식향산 재결정 정제?
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 안식향산 재결정 정제?
The main materials required are: Impure benzoic acid, Distilled water, Activated charcoal.
What results should I expect from 안식향산 재결정 정제?
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.