Проверка закона Бугера–Ламберта–Бера

Демонстрация линейной зависимости между поглощением и концентрацией

Colorimetry Intermediate (High School) 60 мин ~$12,00

Цель

Проверить закон Бугера–Ламберта–Бера, измерив поглощение растворов CuSO₄ различных концентраций и построив калибровочную кривую.

Предпосылки

The Beer-Lambert law states that absorbance is directly proportional to both the concentration of the absorbing species and the path length of the sample (A = εbc). By preparing a series of standard solutions of known concentration and measuring their absorbance at a fixed wavelength, students construct a calibration curve. This curve can then be used to determine the concentration of unknown samples — a technique fundamental to analytical chemistry.

Предупреждения по безопасности

  • CuSO₄ is an irritant — avoid skin contact
  • Do not pipette by mouth
  • Wipe cuvettes with lint-free tissue before measurements
  • Dispose of CuSO₄ solutions in inorganic waste

Требуемые СИЗ

goggles lab_coat

Материалы

  • Copper sulfate (CuSO₄·5H₂O) (10 g)
    For stock solution
  • Distilled water (500 mL)
    Solvent
  • Unknown CuSO₄ solution (50 mL)
    Prepared by instructor

Оборудование

Colorimeter or spectrophotometer Cuvettes (matched pair) Volumetric flasks (100 mL, 6 total) Pipettes (10 mL, 25 mL) Pipette filler Graph paper or computer

Процедура

1

Prepare a 0.5M stock solution by dissolving 12.5 g CuSO₄·5H₂O in distilled water and making up to 100 mL.

5 мин
2

Prepare standard solutions by dilution: 0.05, 0.1, 0.2, 0.3, 0.4, and 0.5 M. Label each flask clearly.

10 мин
3

Set the colorimeter to 635 nm (red filter) — the maximum absorbance wavelength for blue CuSO₄ solutions.

3 мин
4

Zero the instrument using a cuvette of distilled water (blank). Ensure the cuvette is clean and properly oriented.

2 мин
5

Measure and record the absorbance of each standard solution, starting from the most dilute. Rinse the cuvette between samples.

15 мин
6

Measure the absorbance of the unknown solution.

5 мин
7

Plot absorbance (y-axis) vs. concentration (x-axis). Draw the best-fit line and determine the unknown concentration from the graph.

20 мин

Ожидаемые результаты

The plot should show a linear relationship (straight line through the origin) for the standard solutions. The unknown concentration is read from the x-axis at the corresponding absorbance on the calibration curve.

Уборка

Pour CuSO₄ solutions into the inorganic waste container. Rinse all volumetric flasks and cuvettes with distilled water.

Детали

Категория
Colorimetry
Сложность
Intermediate (High School)
Продолжительность
60 мин
Прим. стоимость
$12,00
Шаги
7
Материалы
3

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Frequently Asked Questions

What is the objective of Проверка закона Бугера–Ламберта–Бера?
Проверить закон Бугера–Ламберта–Бера, измерив поглощение растворов CuSO₄ различных концентраций и построив калибровочную кривую.
How difficult is Проверка закона Бугера–Ламберта–Бера?
This experiment is rated as Intermediate (High School). It takes approximately 60 minutes to complete.
What safety precautions are needed for Проверка закона Бугера–Ламберта–Бера?
Key safety precautions include: CuSO₄ is an irritant — avoid skin contact; Do not pipette by mouth; Wipe cuvettes with lint-free tissue before measurements.
What materials are needed for Проверка закона Бугера–Ламберта–Бера?
The main materials required are: Copper sulfate (CuSO₄·5H₂O), Distilled water, Unknown CuSO₄ solution.
What results should I expect from Проверка закона Бугера–Ламберта–Бера?
The plot should show a linear relationship (straight line through the origin) for the standard solutions. The unknown concentration is read from the x-axis at the corresponding absorbance on the calibration curve.