Titulação de Vitamina C com Iodo

Medição do teor de ácido ascórbico em suco de frutas

Titrations Intermediate (High School) 40 min ~$10,00

Objetivo

Determinar o teor de vitamina C (ácido ascórbico) em suco de frutas frescas usando uma titulação com iodo e indicador de amido.

Contexto

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.

Avisos de segurança

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

EPI necessário

goggles lab_coat

Materiais

  • 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)

Equipamentos

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

Procedimento

1

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

3 min Iodine stains
2

Pipette 25.0 mL of orange juice into the Erlenmeyer flask.

2 min
3

Add 5 drops of starch indicator to the flask.

1 min
4

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

8 min
5

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

3 min
6

Record the final volume and repeat for concordant results.

15 min
7

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

5 min

Resultados esperados

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.

Limpeza

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

Detalhes

Categoria
Titrations
Dificuldade
Intermediate (High School)
Duração
40 min
Custo estimado
$10,00
Passos
7
Materiais
4

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Frequently Asked Questions

What is the objective of Titulação de Vitamina C com Iodo?
Determinar o teor de vitamina C (ácido ascórbico) em suco de frutas frescas usando uma titulação com iodo e indicador de amido.
How difficult is Titulação de Vitamina C com Iodo?
This experiment is rated as Intermediate (High School). It takes approximately 40 minutes to complete.
What safety precautions are needed for Titulação de Vitamina C com Iodo?
Key safety precautions include: Iodine stains skin and clothing; Wear safety goggles; Handle iodine solution with care.
What materials are needed for Titulação de Vitamina C com Iodo?
The main materials required are: Fresh orange juice, Iodine solution, Starch indicator solution, Distilled water.
What results should I expect from Titulação de Vitamina C com Iodo?
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.