Why we use acetic acid in iodometric titration?

The iodine is titrated with a standard reducing agent such as sodium thiosulfate or phenylarsine oxide using a starch indicator. Ferric, manganic and nitrite ions interfere, the neutral titration minimizes these interferences. Acetic acid is used for the acid titration.

Which used as a standard in assay of copper sulphate?

The assay is done on the basis of the oxidation-reduction reaction of iodine/thiosulphate. A solution of copper sulphate is first treated with potassium iodide and acetic acid. Cuprous iodide (CuI) is formed with iodine and the liberated iodine is titrated with 0.1 N sodium thiosulphate.

Why Ki is used in the assay of copper sulphate?

Answer: The reaction of copper sulfate in aqueous state and potassium iodide in solid state produces cuprous iodide as a precipitate, liberates iodine gas and forms potassium sulfate in aqueous state.

Why is starch used as an indicator in iodometric 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 role of Sulphuric acid in iodometric titration?

Sulphuric Acid (H2SO4) is used in the redox titration process because it provides the H(+) ions necessary for the reaction to occur more quickly whilst the sulphate(-) ions barely react during the reaction. Therefore, sulfuric acid is added to make the solution acidic.

Why starch indicator is used in iodometric titration?

Why potassium thiocyanate is added in assay of copper sulphate?

The KSCN is added to displace the adsorbed I2 making it accessible to the starch collodial particles, hence yielding a sharper endpoint. The iodine will be titrated with a standardized solution of sodium thiosulfate (Na2S2O3).

Which acid is used to check the hydrolysis of copper sulphate in iodometric titration?

Small amount of acetic acid must be added to check the hydrolysis (for 250ml N/30 CuSO4 solution, about 5ml of acetic acid is added). Questionnaires on Iodometric titration: 1.

What happens when KI is added to CuSO4?

So, when potassium iodide,$KI$ is added to the copper sulphate, $CuS{O_4}$ solution, then they will undergo redox reaction in which iodide ion reduces cupric ion, $C{u^{2 + }}$ to cuprous ion, $C{u^{2 + }}$ (blue to white precipitate)and it themselves get oxidized to iodine gas.

What type of reaction is CuSO4 and Ki?

Type of Chemical Reaction: For this reaction we have a double replacement (sort of) reaction. Balancing Strategies: This is a little bit of a challenging reactions. I recommend trying to get an equal number of iodine atoms on the product side of the reaction.

How to perform the assay of copper sulphate?

The assay is done on the basis of the oxidation-reduction reaction of iodine/thiosulphate. A solution of copper sulphate is first treated with potassium iodide and acetic acid. Cuprous iodide (CuI) is formed with iodine and the liberated iodine is titrated with 0.1 N sodium thiosulphate. Aim: To perform the assay of copper sulphate.

Is there any reason to add acid to deionized copper sulphate solution?

Copper sulphate, if pure enough, will give a clear blue solution in deionised water; no acid is necessary. The only reason for acid is if you use water with a high pH, when you will get a cloud due to the formation of copper hydroxide or most likely, carbonate.

What is the pH of acetic acid in a buffer solution?

For best results, this reaction should be conducted at a pH of around 4 to 5. This pH can be obtained and controlled by the addition of acetic acid and ammonia, which form an acetic acid/acetate buffer. In summary, the acetic acid does not enter into the main reaction, it just provides the optimum pH.

Why is acetic acid a weak acid?

Acetic acid is a weak acid because it doesn’t dissociate very much in solution, meaning there are many more whole molecules of acetic acid than separate acetate and hydrogen ions. Remember, it is the concentration of hydrogen ions that determines the acidity of a solution.