Phân Tích Quang Phổ Hỗn Hợp

Phân giải hỗn hợp hai thành phần bằng phương trình đồng thời

Colorimetry Advanced (University) 75 phút ~$12,00

Mục tiêu

Xác định nồng độ riêng của hai chất màu trong dung dịch hỗn hợp dùng phép đo độ hấp thụ ở hai bước sóng và phương trình đồng thời.

Bối cảnh

When a solution contains two absorbing species with overlapping spectra, a single wavelength measurement cannot determine both concentrations. However, by measuring absorbance at two wavelengths (ideally the λmax of each component) and applying the additive property of absorbance (Beer-Lambert), a system of two simultaneous equations can be solved. This technique is the basis of multicomponent analysis in spectrophotometry.

Cảnh báo an toàn

  • Indicator dyes stain clothing
  • Handle cuvettes by frosted sides only to avoid fingerprints
  • Clean spills immediately

PPE cần thiết

goggles lab_coat

Vật liệu

  • Methyl orange solution (0.01%) (100 mL)
    Component A
  • Bromothymol blue solution (0.01%) (100 mL)
    Component B
  • Unknown mixture of both dyes (50 mL)
    Prepared by instructor
  • Distilled water (200 mL)

Thiết bị

UV-Vis spectrophotometer Cuvettes (matched pair) Volumetric flasks (50 mL, 6 total) Pipettes Calculator

Quy trình

1

Scan pure methyl orange from 350–700 nm. Record λmax (approximately 464 nm in acidic pH).

8 phút
2

Scan pure bromothymol blue from 350–700 nm. Record λmax (approximately 615 nm at neutral pH).

7 phút
3

Prepare 3 standard concentrations of each pure dye. Measure absorbance of each at both λmax values (464 and 615 nm).

15 phút
4

Calculate the molar absorptivity (ε) for each dye at each wavelength from the standard curves: ε(A,464), ε(A,615), ε(B,464), ε(B,615).

15 phút
5

Measure the absorbance of the unknown mixture at both wavelengths.

5 phút
6

Set up the simultaneous equations: A(464) = ε(A,464)·C(A) + ε(B,464)·C(B), A(615) = ε(A,615)·C(A) + ε(B,615)·C(B). Solve for C(A) and C(B).

15 phút
7

Verify your results by comparing the calculated total absorbance at several wavelengths with the measured mixture spectrum.

10 phút

Kết quả dự kiến

The simultaneous equations yield positive concentrations for both dyes. The reconstructed spectrum (sum of individual contributions) should closely match the measured mixture spectrum, validating the Beer-Lambert additivity principle.

Dọn dẹp

Pour dilute dye solutions down the drain with running water. Rinse all cuvettes and volumetric flasks thoroughly.

Chi tiết

Danh mục
Colorimetry
Độ khó
Advanced (University)
Thời gian
75 phút
Chi phí ước tính
$12,00
Số bước
7
Vật liệu
4

Thí nghiệm khác

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Frequently Asked Questions

What is the objective of Phân Tích Quang Phổ Hỗn Hợp?
Xác định nồng độ riêng của hai chất màu trong dung dịch hỗn hợp dùng phép đo độ hấp thụ ở hai bước sóng và phương trình đồng thời.
How difficult is Phân Tích Quang Phổ Hỗn Hợp?
This experiment is rated as Advanced (University). It takes approximately 75 minutes to complete.
What safety precautions are needed for Phân Tích Quang Phổ Hỗn Hợp?
Key safety precautions include: Indicator dyes stain clothing; Handle cuvettes by frosted sides only to avoid fingerprints; Clean spills immediately.
What materials are needed for Phân Tích Quang Phổ Hỗn Hợp?
The main materials required are: Methyl orange solution (0.01%), Bromothymol blue solution (0.01%), Unknown mixture of both dyes, Distilled water.
What results should I expect from Phân Tích Quang Phổ Hỗn Hợp?
The simultaneous equations yield positive concentrations for both dyes. The reconstructed spectrum (sum of individual contributions) should closely match the measured mixture spectrum, validating the Beer-Lambert additivity principle.