What is the reaction between ascorbic acid and iodine?

When ascorbic acid reacts with iodine, the ascorbic acid is oxidized (looses electrons) and the iodine is reduced (gains electrons). As long as the solution contains ascorbic acid, the iodine is used up in a rapid. reaction with ascorbic acid, during which dehydroascorbic acid and iodide ion are formed.

How do you calculate ascorbic acid using titration?

For standard solution Mass Ascorbic acid = Mole iodine × Volume of iodine × 176.12 = 0.00231 × 45 × 176.12 = 91.54 mg Initially, the amount of Ascorbic acid was taken for 100mg and therefore for total amount of ascorbic acid i.e. 250 mg the ratio stands out to be 2.5 (250/100).

What is the titration type between ascorbic acid and iodine?

iodometric titration
The experiment involves an iodometric titration in which iodine reacts with ascorbic acid, oxidizing it to dehydroascorbic acid. The redox titration endpoint is determined by the first iodine excess that is complexed with starch, giving a deep blue-violet color.

What is the stoichiometry between iodine and vitamin C?

results in 26.95 mM for iodine solution concentration. Since the reaction reveals a I : 1 stoichiometry ratio between iodine and ascorbic acid, the number of moles of iodine reduced is equivalent to the moles of vitamin C oxidized at the titration end point.

What is the purpose of titrating vitamin C ascorbic acid with the iodine solution?

This titration procedure is appropriate for testing the amount of vitamin C in vitamin C tablets, juices, and fresh, frozen, or packaged fruits and vegetables. The titration can be performed using just iodine solution and not iodate, but the iodate solution is more stable and gives a more accurate result.

Does ascorbic acid reduce iodine?

Ascorbic acid reduces iodine to iodide ions, and in the process it is oxidised to dehydroascorbic acid. We can show that elemental iodine is present in solution by using starch to give a characteristic blue–black colour.

How do you calculate the dye factor of ascorbic acid?

Standardization of dye: To 5 ml of Standard ascorbic acid (1ml=0.1mg) and 5 ml HPO3. Titrate this solution with the dye solution to a pink colour which should persist for 15 seconds….

1. Given: Wt of sample = 10g.
2. Volume made up = 250 ml.
3. ml of sample taken for estimation = 10ml.
4. Dye factor = 0.1.
5. Titre value = 5ml.

What is the principle of vitamin C titration?

The principle of this method is a titration with dichlorophenolindophenol (or phenol-indo-2:6-dichlorophenol, also known as DCPIP). Ascorbic acid reacts with DCPIP, changing the colour from blue to colourless.

Why is iodine used in vitamin C titration?

As the iodine is added during the titration, the ascorbic acid is oxidised to dehydroascorbic acid, while the iodine is reduced to iodide ions. Due to this reaction, the iodine formed is immediately reduced to iodide as long as there is any ascorbic acid present.

Why we used starch indicator in case of ascorbic acid and iodine titration?

3. The concentration of the prepared iodine solution can be more accurately determined by titration with a standard solution of ascorbic acid or a standard solution of potassium thiosulfate using a starch indicator. This should be done if possible as iodine solutions can be unstable.

Why does ascorbic acid clear iodine?

Iodine also binds to ascorbic acid. When it binds to vitamin C, it is colorless. Iodine binds more strongly to ascorbic acid than it binds to starch. The iodine, therefore, leaves the starch and binds to ascorbic acid, which would make the blue solution become clear.”

What are the different methods of estimation of ascorbic acid?

Titrimetric methods – The 2, 6 dichlorophenol indophenol method is the common titrimetric method used for determination of ascorbic acid. 2. Colorimetric methods – The 2, 4 dinitrophenyl hydrazine method is a common colorimetric method used for estimation of ascorbic acid in solutions and foods.

How do you test the purity of ascorbic acid?

Procedure. Weigh accurately about 0.1 gm of the sample and dissolve in a mixture of 100 ml freshly boiled and cooled water and 25 ml of 1M sulfuric acid. Immediately titrate with 0.05M iodine, using the starch solution as indicator until a persistent blue-violet color is obtained.

What is the purpose of titrating vitamin C with iodine?

Vitamin C, more properly called ascorbic acid, is an essential antioxidant needed by the human body (see additional notes). As the iodine is added during the titration, the ascorbic acid is oxidised to dehydroascorbic acid, while the iodine is reduced to iodide ions.

Why is 0.1 ascorbic acid solution used as the standard?

Ascorbic acid is used as standard because of its availability in different food sources (especially citrus fruit extracts).

How do you calculate moles of vitamin C?

To calculate moles of ascorbic acid, divide the number of grams in our sample by the formula weight, 176.1 g/mol. Hint: The number of moles is: 0.010 g / 176.1 g/mol = 5.6786e-5 moles of ascorbic acid.

Why is a 0.1% ascorbic acid solution used as the standard?

How do you titrate ascorbic acid with iodine?

Pipette aliquot of the ascorbic acid solution into Erlenmeyer flask (100 or 200 mL, depending on the sample volume). Add 5 mL of starch solution. Titrate with iodine solution until a faint blue color persists after 20 seconds of swirling the solution.

What is the role of ascorbic acid in iodine reaction?

The high concentration of ascorbic acid allows all of the iodine to react with the vitamin C. (see left panel) Quick version: This demo is a variation on the one above, using the same concentrations in the two solutions.. Different Approach version: In this clip, the set up for the discrepant event is shown at the start.

How do you measure Vitamin C by iodine titration?

Vitamin C Determination by Iodine Titration. Peter Dazeley/Getty Images. One way to determine the amount of vitamin C in food is to use a redox titration. The redox reaction is better than an acid-base titration since there are additional acids in a juice, but few of them interfere with the oxidation of ascorbic acid by iodine.

How do you convert iodine to dehydroascorbic acid?

Iodine is relatively insoluble, but this can be improved by complexing the iodine with iodide to form triiodide: I2 + I- <–> I3-. Triiodide oxidizes vitamin C to form dehydroascorbic acid: C6H8O6 + I3- + H2O –> C6H6O6 + 3I- + 2H+.