高锰酸钾氧化还原滴定

用KMnO₄测定铁(II)浓度

Titrations Advanced (University) 50 分钟 ~$18.00

目标

用标准高锰酸钾溶液（自身指示剂）滴定硫酸亚铁溶液，测定其浓度。

背景

Potassium permanganate is a powerful oxidizing agent that reacts with Fe2+ in acidic solution. MnO4- (purple) is reduced to Mn2+ (nearly colorless), so permanganate acts as its own indicator. The endpoint occurs when a single drop of excess KMnO4 produces a permanent pink/purple color.

安全警告

  • KMnO₄ stains skin and clothing permanently
  • H₂SO₄ is corrosive
  • Wear safety goggles and gloves throughout
  • Wipe up KMnO₄ spills immediately

所需PPE

goggles gloves lab_coat

材料

  • Iron(II) sulfate solution (100 mL)
    Unknown concentration
  • Potassium permanganate (KMnO₄) (100 mL)
    0.02M standardized
  • Sulfuric acid (H₂SO₄) (50 mL)
    1M
  • Distilled water (200 mL)

设备

50 mL burette Burette stand and clamp 250 mL Erlenmeyer flask 25 mL pipette Pipette filler White tile

步骤

1

Rinse the burette with KMnO₄ solution, then fill to the 0 mL mark. Record the meniscus reading (read from the top of the meniscus since KMnO₄ is opaque).

5 分钟 KMnO₄ stains — handle carefully
2

Pipette exactly 25.0 mL of iron(II) sulfate solution into the Erlenmeyer flask.

3 分钟
3

Add 10 mL of 1M sulfuric acid to the flask to ensure acidic conditions.

2 分钟 Handle acid carefully
4

Slowly add KMnO₄ from the burette while swirling. Each drop will decolorize as Fe2+ reduces MnO4-.

10 分钟
5

As the endpoint approaches, add drop by drop until a faint permanent pink/purple color persists for 30 seconds.

5 分钟
6

Record the final burette reading and calculate the volume used.

2 分钟
7

Repeat at least twice for concordant results.

15 分钟
8

Calculate the Fe2+ concentration using the balanced equation: MnO4- + 5Fe2+ + 8H+ → Mn2+ + 5Fe3+ + 4H2O.

5 分钟

预期结果

The solution should transition from colorless to a persistent faint pink/purple at the endpoint. The 1:5 molar ratio of KMnO₄ to Fe2+ should yield an accurate concentration.

清理

Dilute waste solutions and dispose of KMnO₄ waste according to lab protocols. Rinse the burette thoroughly with water. Clean any stains with dilute acid or sodium sulfite.

详情

类别
Titrations
难度
Advanced (University)
时长
50 分钟
预估费用
$18.00
步骤数
8
材料
4

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Frequently Asked Questions

What is the objective of 高锰酸钾氧化还原滴定?
用标准高锰酸钾溶液（自身指示剂）滴定硫酸亚铁溶液，测定其浓度。
How difficult is 高锰酸钾氧化还原滴定?
This experiment is rated as Advanced (University). It takes approximately 50 minutes to complete.
What safety precautions are needed for 高锰酸钾氧化还原滴定?
Key safety precautions include: KMnO₄ stains skin and clothing permanently; H₂SO₄ is corrosive; Wear safety goggles and gloves throughout.
What materials are needed for 高锰酸钾氧化还原滴定?
The main materials required are: Iron(II) sulfate solution, Potassium permanganate (KMnO₄), Sulfuric acid (H₂SO₄), Distilled water.
What results should I expect from 高锰酸钾氧化还原滴定?
The solution should transition from colorless to a persistent faint pink/purple at the endpoint. The 1:5 molar ratio of KMnO₄ to Fe2+ should yield an accurate concentration.