Thử Nghiệm Beilstein Cho Halogen

Phát hiện nguyên tử halogen trong hợp chất hữu cơ bằng thử nghiệm ngọn lửa dây đồng

Qualitative Analysis Beginner (Middle School) 25 phút ~$5,00

Mục tiêu

Xác định liệu hợp chất hữu cơ có chứa nguyên tử halogen (Cl, Br, I) hay không bằng thử nghiệm Beilstein dây đồng.

Bối cảnh

The Beilstein test is a simple qualitative test for halogens in organic compounds. A copper wire is heated in a flame to form copper(II) oxide, then dipped in the test substance and returned to the flame. If a halogen is present, volatile copper halide forms and imparts a green or blue-green color to the flame. The test is sensitive but not specific (it does not distinguish between Cl, Br, and I, and can give false positives with some nitrogen compounds).

Cảnh báo an toàn

  • Chloroform is toxic — avoid inhalation and skin contact
  • Work in a fume hood when testing volatile organics
  • Hot copper wire can cause burns
  • Keep flammable solvents away from the flame

PPE cần thiết

goggles gloves lab_coat

Vật liệu

  • Copper wire (20 gauge) (15 cm)
    Make a small loop at one end
  • Chloroform (CHCl₃) (2 mL)
    Positive control
  • Ethanol (C₂H₅OH) (2 mL)
    Negative control
  • Unknown organic samples (2 mL each)
    3–4 samples
  • Cork or holder for copper wire (1)

Thiết bị

Bunsen burner Watch glasses (6) Forceps

Quy trình

1

Heat the copper wire loop in the oxidizing zone of the Bunsen burner until it glows red and no green color is visible (this burns off contaminants and forms CuO).

3 phút Wire is extremely hot
2

Allow the wire to cool slightly, then dip it into the chloroform (positive control). Return the wire to the flame.

3 phút Chloroform is volatile — use fume hood
3

Observe the bright green flame (positive result for halogen). Record the color and intensity.

2 phút
4

Clean the wire by heating until green color disappears. Repeat the test with ethanol (negative control). No green color should appear.

3 phút
5

Test each unknown sample using the same procedure. Record whether each gives a positive (green) or negative result.

10 phút Clean wire between samples
6

Record all results and identify which unknowns likely contain halogen atoms.

4 phút

Kết quả dự kiến

Chloroform produces a vivid green flame (positive). Ethanol produces no green color (negative). Halogen-containing unknowns show green coloration of varying intensity.

Dọn dẹp

Allow copper wire to cool. Store organic waste in halogenated or non-halogenated solvent waste containers as appropriate. Wipe down surfaces.

Chi tiết

Danh mục
Qualitative Analysis
Độ khó
Beginner (Middle School)
Thời gian
25 phút
Chi phí ước tính
$5,00
Số bước
6
Vật liệu
5

Thí nghiệm khác

Các Thử Nghiệm Nhận Biết Anion 60 min Cầu Vồng Chỉ Thị pH 45 min Nhận Biết Cation Bằng Kết Tủa 90 min Quang Phổ Phát Xạ Ngọn Lửa 60 min Sắc Ký Sắc Tố Thực Vật 60 min Thử Nghiệm Độ Cứng Nước Bằng Dung Dịch Xà Phòng 40 min Thử Nghiệm Hạt Borax Cho Ion Kim Loại 45 min Thử Nghiệm Tinh Bột-Iot Cho Carbohydrat 30 min Thử Thách Nhận Biết Chất Chưa Biết 75 min

Frequently Asked Questions

What is the objective of Thử Nghiệm Beilstein Cho Halogen?
Xác định liệu hợp chất hữu cơ có chứa nguyên tử halogen (Cl, Br, I) hay không bằng thử nghiệm Beilstein dây đồng.
How difficult is Thử Nghiệm Beilstein Cho Halogen?
This experiment is rated as Beginner (Middle School). It takes approximately 25 minutes to complete.
What safety precautions are needed for Thử Nghiệm Beilstein Cho Halogen?
Key safety precautions include: Chloroform is toxic — avoid inhalation and skin contact; Work in a fume hood when testing volatile organics; Hot copper wire can cause burns.
What materials are needed for Thử Nghiệm Beilstein Cho Halogen?
The main materials required are: Copper wire (20 gauge), Chloroform (CHCl₃), Ethanol (C₂H₅OH), Unknown organic samples, Cork or holder for copper wire.
What results should I expect from Thử Nghiệm Beilstein Cho Halogen?
Chloroform produces a vivid green flame (positive). Ethanol produces no green color (negative). Halogen-containing unknowns show green coloration of varying intensity.