ヨウ素によるビタミンC滴定

果汁中のアスコルビン酸含量を測定する

Titrations Intermediate (High School) 40 分 ~$10.00

目的

デンプン指示薬を用いたヨウ素滴定により、新鮮な果汁中のビタミンC（アスコルビン酸）含量を決定する。

背景

Ascorbic acid reduces iodine to iodide ions in a 1:1 molar ratio. Starch indicator turns dark blue-black in the presence of excess iodine. When all the vitamin C is consumed, the next drop of iodine produces the blue-black color, marking the endpoint.

安全上の警告

  • Iodine stains skin and clothing
  • Wear safety goggles
  • Handle iodine solution with care

必要なPPE

goggles lab_coat

材料

  • Fresh orange juice (200 mL)
    Freshly squeezed preferred
  • Iodine solution (100 mL)
    0.005M
  • Starch indicator solution (10 mL)
    1% solution
  • Distilled water (200 mL)

器具

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

手順

1

Rinse and fill the burette with the standardized iodine solution. Record the initial volume.

3 分 Iodine stains
2

Pipette 25.0 mL of orange juice into the Erlenmeyer flask.

2 分
3

Add 5 drops of starch indicator to the flask.

1 分
4

Titrate by adding iodine solution slowly while swirling. The brown iodine color will disappear as it reacts with vitamin C.

8 分
5

Near the endpoint, add drop by drop until a persistent dark blue-black color appears for 20 seconds.

3 分
6

Record the final volume and repeat for concordant results.

15 分
7

Calculate the mass of vitamin C per volume of juice. Compare with the labeled value.

5 分

予想される結果

Fresh orange juice typically contains 40-80 mg of vitamin C per 100 mL. The starch-iodine endpoint should be a sharp transition to blue-black. Older or heat-treated juice will show lower vitamin C content.

後片付け

Dispose of iodine waste in designated containers. Rinse all glassware with water. Clean any iodine stains with sodium thiosulfate solution.

詳細

カテゴリ
Titrations
難易度
Intermediate (High School)
所要時間
40 分
推定費用
$10.00
ステップ数
7
材料
4

その他の実験

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Frequently Asked Questions

What is the objective of ヨウ素によるビタミンC滴定?
デンプン指示薬を用いたヨウ素滴定により、新鮮な果汁中のビタミンC（アスコルビン酸）含量を決定する。
How difficult is ヨウ素によるビタミンC滴定?
This experiment is rated as Intermediate (High School). It takes approximately 40 minutes to complete.
What safety precautions are needed for ヨウ素によるビタミンC滴定?
Key safety precautions include: Iodine stains skin and clothing; Wear safety goggles; Handle iodine solution with care.
What materials are needed for ヨウ素によるビタミンC滴定?
The main materials required are: Fresh orange juice, Iodine solution, Starch indicator solution, Distilled water.
What results should I expect from ヨウ素によるビタミンC滴定?
Fresh orange juice typically contains 40-80 mg of vitamin C per 100 mL. The starch-iodine endpoint should be a sharp transition to blue-black. Older or heat-treated juice will show lower vitamin C content.