Определение железа в воде

Измерение концентрации растворённого железа роданидным колориметрическим методом

Colorimetry Intermediate (High School) 75 мин ~$10,00

Цель

Определить концентрацию ионов железа(III) в пробе воды роданидным колориметрическим методом.

Предпосылки

Iron(III) ions react with thiocyanate ions (SCN⁻) to form the intensely red-colored complex [Fe(SCN)]²⁺. The intensity of the red color is proportional to the Fe³⁺ concentration, following the Beer-Lambert law. This method is widely used in water quality testing and environmental monitoring. Students learn both the analytical technique and the chemistry of complex ion formation.

Предупреждения по безопасности

  • FeCl₃ solution stains skin and clothing
  • KSCN is harmful if swallowed
  • HNO₃ is corrosive — handle with care
  • Dispose of thiocyanate waste in designated containers

Требуемые СИЗ

goggles gloves lab_coat

Материалы

  • Iron(III) chloride (FeCl₃) standard (100 mL)
    0.01 M stock solution
  • Potassium thiocyanate (KSCN) (100 mL)
    0.1 M solution
  • Dilute HNO₃ (0.1 M) (50 mL)
    To maintain acidity
  • Water sample (50 mL)
    Unknown iron content
  • Distilled water (500 mL)
    For dilutions

Оборудование

Colorimeter or spectrophotometer Cuvettes (matched pair) Volumetric flasks (50 mL, 7 total) Pipettes (1 mL, 5 mL, 10 mL) Pipette filler

Процедура

1

Prepare a series of standard Fe³⁺ solutions (0, 1, 2, 4, 6, 8, 10 ppm) by diluting the stock FeCl₃ solution in 50 mL volumetric flasks.

15 мин
2

Add 5 mL of 0.1 M KSCN and 2 mL of dilute HNO₃ to each standard flask and the water sample. Make up to volume with distilled water.

10 мин
3

Allow 5 minutes for full color development. The solutions should range from pale to deep red.

5 мин
4

Set the colorimeter to 480 nm. Zero with the blank solution (0 ppm Fe³⁺ + KSCN).

5 мин
5

Measure the absorbance of each standard solution and the water sample.

15 мин
6

Plot the calibration curve (absorbance vs. concentration). Use it to determine the iron concentration in the water sample.

15 мин
7

Calculate the iron concentration and evaluate whether the water meets drinking water standards (<0.3 ppm).

10 мин

Ожидаемые результаты

The calibration curve should be linear from 0 to 10 ppm. The deep red color of [Fe(SCN)]²⁺ intensifies with increasing Fe³⁺ concentration. The water sample's iron content is determined from the calibration curve.

Уборка

Collect all thiocyanate-containing solutions in labeled waste. Rinse all glassware thoroughly. Wipe down the colorimeter.

Детали

Категория
Colorimetry
Сложность
Intermediate (High School)
Продолжительность
75 мин
Прим. стоимость
$10,00
Шаги
7
Материалы
5

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Frequently Asked Questions

What is the objective of Определение железа в воде?
Определить концентрацию ионов железа(III) в пробе воды роданидным колориметрическим методом.
How difficult is Определение железа в воде?
This experiment is rated as Intermediate (High School). It takes approximately 75 minutes to complete.
What safety precautions are needed for Определение железа в воде?
Key safety precautions include: FeCl₃ solution stains skin and clothing; KSCN is harmful if swallowed; HNO₃ is corrosive — handle with care.
What materials are needed for Определение железа в воде?
The main materials required are: Iron(III) chloride (FeCl₃) standard, Potassium thiocyanate (KSCN), Dilute HNO₃ (0.1 M), Water sample, Distilled water.
What results should I expect from Определение железа в воде?
The calibration curve should be linear from 0 to 10 ppm. The deep red color of [Fe(SCN)]²⁺ intensifies with increasing Fe³⁺ concentration. The water sample's iron content is determined from the calibration curve.