التحقق من قانون بير-لامبرت

إظهار العلاقة الخطية بين الامتصاص والتركيز

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

الهدف

التحقق من قانون بير-لامبرت بقياس امتصاص محاليل كبريتات النحاس عند تركيزات مختلفة ورسم منحنى المعايرة.

الخلفية

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.

تحذيرات السلامة

  • 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

معدات الوقاية الشخصية المطلوبة

goggles lab_coat

المواد

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

المعدات

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

الإجراء

1

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

5 دقيقة
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 دقيقة
3

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

3 دقيقة
4

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

2 دقيقة
5

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

15 دقيقة
6

Measure the absorbance of the unknown solution.

5 دقيقة
7

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

20 دقيقة

النتائج المتوقعة

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.

التنظيف

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

التفاصيل

الفئة
Colorimetry
الصعوبة
Intermediate (High School)
المدة
60 دقيقة
التكلفة التقديرية
$12,00
الخطوات
7
المواد
3

مزيد من التجارب

التحديد الطيفي للأسبرين 75 min التحديد اللوني للجلوكوز 60 min التحديد اللوني للفوسفات 90 min التحليل الطيفي الضوئي لخليط 75 min تحديد الحديد في الماء 75 min تحليل صبغة الطعام بالمطياف الضوئي 60 min فحص البروتين اللوني (طريقة برادفورد) 60 min

Frequently Asked Questions

What is the objective of التحقق من قانون بير-لامبرت?
التحقق من قانون بير-لامبرت بقياس امتصاص محاليل كبريتات النحاس عند تركيزات مختلفة ورسم منحنى المعايرة.
How difficult is التحقق من قانون بير-لامبرت?
This experiment is rated as Intermediate (High School). It takes approximately 60 minutes to complete.
What safety precautions are needed for التحقق من قانون بير-لامبرت?
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 التحقق من قانون بير-لامبرت?
The main materials required are: Copper sulfate (CuSO₄·5H₂O), Distilled water, Unknown CuSO₄ solution.
What results should I expect from التحقق من قانون بير-لامبرت?
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.