What are the purpose of adding sulfuric acid before the titration?

Titrations with Permanganate must be carried out in strong acid solution. Sulfuric Acid is generally used for this purpose because Nitric Acid and Hydrochloric Acid can participate in competing oxidation-reduction reactions, reducing the accuracy of the titration.

Why is HCl added for the titration of vitamin C?

Hydrochloric acid (HCl) is added during titration of vitamin C (C6H8O6) because the reaction should be carried out in an acidic medium.

What acts as an indicator in ascorbic acid titration?

Vitamin C, more properly called ascorbic acid, is an essential antioxidant needed by the human body (see additional notes). Once all the ascorbic acid has been oxidised, the excess iodine is free to react with the starch indicator, forming the blue-black starch-iodine complex. This is the endpoint of the titration.

What is the role of Sulphuric acid in titration of ascorbic acid?

In the process of titration, the addition of sulfuric acid give an acidic condition in the solution of vitamin C when the titration process occurs with iodine standard solution.

What is the purpose of adding the sulfuric acid?

Concentrated sulfuric acid is used as a catalyst, and has a dual role: Speeds up the reaction. Acts as a dehydrating agent, forcing the equilibrium to the right and resulting in a greater yield of ester.

What is the role of sulfuric acid in a redox titration?

Sulfuric acid is used because it is stable towards oxidation; whereas, for example, hydrochloric acid would be oxidized to chlorine by permanganate. There are three reasons: to provide acidic medium. to oxidize Mn+2 to Mn+3.

What is the role of HCl in iodometric titration?

In iodometric determination of sulfide two reactions are taking place when alkaline solution is added to HCl acid-iodine. To eliminate the side reaction in iodometric titration, the sulfide solution must be acidic when it is mixed with HCl-iodine.

Why ascorbic acid is a reducing agent?

It is a mild reducing agent and antioxidant. It is oxidized with loss of one electron to form a radical cation and then with loss of a second electron to form dehydroascorbic acid. It typically reacts with oxidants of the reactive oxygen species, such as the hydroxyl radical.

What is the role of starch in the titration?

In an iodometric titration, a starch solution is used as an indicator since it can absorb the I 2 that is released. This absorption will cause the solution to change its colour from deep blue to light yellow when titrated with standardised thiosulfate solution. This indicates the end point of the titration.

What is the expected end point of the assay of ascorbic acid?

The endpoint occurs when the dark color does not fade after 20 seconds of swirling. Perform two more trials. If the first titration requires less than 20 mL of KIO3, increase the mass of unknown slightly in subsequent trials. Calculate the milligrams of ascorbic acid per gram of sample.

What is the purpose of adding concentrated sulfuric acid and heating the mixture?

Because the concentrated acid has a fairly high boiling point, it can be used to release more volatile acids from their salts, e.g., when sodium chloride (NaCl), or common salt, is heated with concentrated sulfuric acid, hydrogen chloride gas, HCl, is evolved.