Why is iodine used in KF titration?

Coulometric KF analysis requires only one, iodide-containing, solution. Iodine needed for KF reaction is produced by anodic oxidation of iodide from solution and the endpoint is detected electrochemically. Coulometric determination is best suited for samples with less than 1% of water.

What is the reaction of Karl Fischer reagent?

What is the Karl Fischer Reaction? The alcohol reacts with sulfur dioxide (SO2) and base to form an intermediate alkylsulfite salt, which is then oxidized by iodine to an alkylsulfate salt. This oxidation reaction consumes water.

Which type of reaction is involved in Karl Fischer titration?

oxidation reaction
The principle of Karl Fischer titration is based on the oxidation reaction between iodine and sulphur dioxide. Water reacts with iodine and sulphur dioxide to form sulphur trioxide and hydrogen iodide. An endpoint is reached when all the water is consumed.

What does Karl Fischer titration measure?

Karl Fischer Titration is a technique for the determination of moisture content. The technique was developed by a chemist named Karl Fischer. It is based on a reagent which reacts with water and converts the water into a non-conductive chemical.

Why we use sodium tartrate in Karl Fischer?

Sodium tartrate dihydrate is the volumetric standard for Karl Fischer titration. Under normal conditions, it is stable and non-hygroscopic. Sodium tartrate dihydrate has a stoichiometric water content of 15.66% and is primarily used for titer determination in volumetry.

What is the limit of KF factor?

Standardization is valid, if concentration should be not less than 5 mg and not more than 7mg. The relative Standard deviation between two average KF factors of water and DST determined consecutively should not be more than 3.0 % [Average of two factors (2 with water and 2 with DST) to be considered for calculation.]

Why is methanol used as solvent in KF titration?

The role of the solvent is to contribute to the chemical reaction and to ensure the sample is releasing all its moisture content. Most liquid samples dissolve in methanol, which is the usual solvent in Karl Fischer determinations. To determine the total amount of water, the sample must dissolve completely.

Which reagent is used in Karl Fischer analysis?

Aquastar® Reagents for Volumetric Karl Fischer Titration The volumetric Karl Fischer titration method is used to determine water content by adding iodine containing titrant to the sample, which is then dissolved or dispersed in a suitable solvent.

Why Karl Fischer titration is used?

Karl Fischer (KF) titration is a redox reaction which uses the consumption of water during the reaction to measure the amount of water in a sample. It is the reference method for water determination because of its specificity, accuracy and speed of measurement. It takes place in an organic solvent.

Why KF reagent is pyridine free?

An essentially pyridine-free Karl Fischer reagent useful in the determination of water, comprises a dissolving agent containing sulfur dioxide and a pyridine substitute in a Karl Fischer solvent, and a titrating agent containing iodine in a Karl Fischer solvent, wherein the pyridine substitute is an alkali or alkaline …

What is water factor limit?

The water equivalence factor F, in mg of water per mL of reagent, is given by the formula: 2(18.02/230.08)(W/V)

Why DMF is used in KF?

Hydranal-Formamide dry accelerates the speed of KF reaction. Because it can also influence the stoichiometry of the reaction, formamide should not be used at concentrations >50% by volume.

Is pyridine volatile?

In daily life, trace amounts of pyridine are components of the volatile organic compounds that are produced in roasting and canning processes, e.g. in fried chicken, sukiyaki, roasted coffee, potato chips, and fried bacon.

What is the structure of pyridine?

C5H5NPyridine / Formula

What is pyridine free KF reagent?

The pyridine-free Karl Fischer reagent consists of two solutions, a dissolving agent and a titrating agent. The dissolving agent contains sulfur dioxide and a pyridine substitute in a solvent and is used for taking up the sample to be investigated with respect to its water content.

Is DMF basic or acidic?

In pubchem, i found the pKa of DMF is -0.3. However it is a strong base, which means its pKa value should be high (>16).

Which solvent is use for KF?

Karl Fischer reagent consists of iodine, sulfur dioxide, a base and a solvent, such as alcohol.

What is the pH of pyridine?

Therefore, the pH of the pyridine solution is 9.43.

Is pyridine acidic or basic?

basic
The nitrogen center of pyridine features a basic lone pair of electrons. This lone pair does not overlap with the aromatic π-system ring, consequently pyridine is basic, having chemical properties similar to those of tertiary amines.

Is pyridine electron withdrawing or donating?

Compare the reactivity of pyridine to that of Benzene in electrophilic aromatic substitution. Answer: Pyridine is less reactive, than benzene toward electrophilic aromatic substitution, because nitrogen is more electronegative, than carbon and acts like an electron withdrawing group.