Analisis Spektrofotometrik Campuran

Menguraikan campuran dua komponen menggunakan persamaan simultan

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

Tujuan

Tentukan konsentrasi individual dua pewarna dalam larutan campuran menggunakan pengukuran absorbansi pada dua panjang gelombang dan persamaan simultan.

Latar Belakang

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.

Peringatan Keselamatan

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

APD yang Diperlukan

goggles lab_coat

Bahan

  • 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)

Peralatan

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

Prosedur

1

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

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2

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

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3

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

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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).

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5

Measure the absorbance of the unknown mixture at both wavelengths.

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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).

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7

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

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Hasil yang Diharapkan

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.

Pembersihan

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

Detail

Kategori
Colorimetry
Tingkat Kesulitan
Advanced (University)
Durasi
75 menit
Perkiraan Biaya
$12,00
Langkah
7
Bahan
4

Eksperimen Lainnya

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Frequently Asked Questions

What is the objective of Analisis Spektrofotometrik Campuran?
Tentukan konsentrasi individual dua pewarna dalam larutan campuran menggunakan pengukuran absorbansi pada dua panjang gelombang dan persamaan simultan.
How difficult is Analisis Spektrofotometrik Campuran?
This experiment is rated as Advanced (University). It takes approximately 75 minutes to complete.
What safety precautions are needed for Analisis Spektrofotometrik Campuran?
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 Analisis Spektrofotometrik Campuran?
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 Analisis Spektrofotometrik Campuran?
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.