漂白剤のヨウ素滴定

家庭用漂白剤中の次亜塩素酸ナトリウム濃度の決定

Titrations Advanced (University) 50 分 ~$15.00

目的

チオ硫酸ナトリウムを用いたヨウ素滴定により、市販漂白剤中の次亜塩素酸ナトリウム（NaOCl）濃度を決定する。

背景

In iodometric titrations, the analyte (hypochlorite) oxidizes iodide ions to iodine, which is then titrated with sodium thiosulfate. The endpoint is detected using starch indicator. This indirect method is widely used for determining the concentration of oxidizing agents.

安全上の警告

  • Bleach is an irritant and oxidizer
  • Do not mix bleach with acid in large quantities — produces chlorine gas
  • Work in a well-ventilated area or fume hood
  • Wear safety goggles and gloves

必要なPPE

goggles gloves lab_coat

材料

  • Household bleach (50 mL)
    Dilute 1:10 before use
  • Potassium iodide (KI) (5 g)
    Excess
  • Sodium thiosulfate (Na₂S₂O₃) (100 mL)
    0.1M standardized
  • Starch indicator (10 mL)
    1% solution
  • Acetic acid (CH₃COOH) (20 mL)
    2M
  • Distilled water (300 mL)

器具

50 mL burette Burette stand and clamp 250 mL Erlenmeyer flask 25 mL pipette 25 mL volumetric flask

手順

1

Prepare a 1:10 dilution of the bleach with distilled water in the volumetric flask.

3 分 Bleach is irritating
2

Pipette 25.0 mL of the diluted bleach into the Erlenmeyer flask.

2 分
3

Add approximately 2 g of potassium iodide. The solution will turn brown/yellow as iodine is liberated.

2 分
4

Add 10 mL of 2M acetic acid to acidify the solution.

1 分 Work in ventilated area
5

Fill the burette with 0.1M sodium thiosulfate. Begin titrating the brown iodine solution.

5 分
6

When the solution becomes pale yellow, add 1 mL of starch indicator. The solution turns dark blue.

2 分
7

Continue titrating drop by drop until the blue color disappears and the solution becomes colorless.

5 分
8

Record the volume. Repeat for concordant results. Calculate the NaOCl concentration accounting for the dilution.

15 分

予想される結果

Household bleach typically contains 3-8% NaOCl. The endpoint should show a sharp transition from blue to colorless. Multiple concordant results should agree within 0.10 mL.

後片付け

Neutralize iodine waste with sodium thiosulfate before disposal. Rinse all glassware. Ensure proper ventilation during cleanup.

詳細

カテゴリ
Titrations
難易度
Advanced (University)
所要時間
50 分
推定費用
$15.00
ステップ数
8
材料
6

その他の実験

EDTA錯体滴定による水の硬度測定 45 min pH滴定曲線 50 min フェノールフタレインを用いた酸塩基滴定 45 min メチルオレンジを用いた酸塩基滴定 40 min ヨウ素によるビタミンC滴定 40 min 二重指示薬による炭酸塩・重炭酸塩混合物の滴定 55 min 制酸剤錠剤の逆滴定 60 min 沈殿滴定（モール法） 45 min 過マンガン酸カリウムによる酸化還元滴定 50 min 電導度滴定 50 min

Frequently Asked Questions

What is the objective of 漂白剤のヨウ素滴定?
チオ硫酸ナトリウムを用いたヨウ素滴定により、市販漂白剤中の次亜塩素酸ナトリウム（NaOCl）濃度を決定する。
How difficult is 漂白剤のヨウ素滴定?
This experiment is rated as Advanced (University). It takes approximately 50 minutes to complete.
What safety precautions are needed for 漂白剤のヨウ素滴定?
Key safety precautions include: Bleach is an irritant and oxidizer; Do not mix bleach with acid in large quantities — produces chlorine gas; Work in a well-ventilated area or fume hood.
What materials are needed for 漂白剤のヨウ素滴定?
The main materials required are: Household bleach, Potassium iodide (KI), Sodium thiosulfate (Na₂S₂O₃), Starch indicator, Acetic acid (CH₃COOH).
What results should I expect from 漂白剤のヨウ素滴定?
Household bleach typically contains 3-8% NaOCl. The endpoint should show a sharp transition from blue to colorless. Multiple concordant results should agree within 0.10 mL.