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Anonymous users2024-02-06The iodine value of oils and fats is used to indicate the degree of unsaturation of fatty acids in oils and fats.
The iodine value refers to the number of grams of iodine that can be absorbed (added) in 100g of substance. It is mainly used for the determination of oil and fat substances. The greater the degree of unsaturation, the higher the iodine value.
The iodine value of dry oils is greater than that of non-dry oils. For example, the iodine value of dry oil is above 130; The iodine value of semi-dry oils is between 100 and 130; The iodine value of non-dry oils is below 100.
Test method: Prepare Wijs reagent first, iodine chloride is dissolved in acetic acid at a concentration, and the number of fibrillation analyses of the oil sample depends on the degree of unsaturation, so that the Wijs reagent has a 100% 150% excess. The sample was dissolved in 20ml of carbon tetrachloride, and then the above reagents were added, and the temperature was maintained for 20 25 and 30min; Add 20 ml of potassium iodide solution [15% (mass)] and 100 ml of water, titrate with sodium thiosulfate, and starch solution (10%) as indicator.
It should be noted that if there are two or more olene groups in the molecular structure of the oil, the iodine value is only true if these alkene groups are in the unconjugated state.
An impulse indicator that indicates the degree of unsaturation of organic matter. is an important percentage of the iodine that can be absorbed by the sample. It is mainly used for the determination of oils, waxes, fatty acids and other substances.
The greater the degree of unsaturation, the greater the iodine value. For example, the iodine value of dry oil is above 130; The iodine value of semi-dry oils is between 100 and 130; The iodine value of non-dry oils is below 100. The iodine value of terrestrial animal fats is below 80; The iodine value of marine animal fats and fats is above 100. The usual methods used to determine iodine value are:
1) The carbon tetrachloride solution of oils and fats is titrated with ethanol solution of iodine and mercuric dichloride; (2) titration with glacial acetic acid solution of iodine chloride; (3) Titration with glacial acetic acid solution containing pyridine, bromine and concentrated sulfuric acid.
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Anonymous users2024-02-05Summary. Pro-<>
Hello, why can't the oil iodine value determination weigh the sample directly in the iodine valence bottle? Iodine value determination of fats and oils is a chemical analysis method used to determine the degree of unsaturation in oils and fats. In this method, the oil to be tested is added to the iodine valence flask, and then a certain amount of iodine solution is added.
The iodine will be bound to the unsaturated, and the remaining iodine will then be titrated to the reduction. Depending on the amount of iodine consumed, the degree of unsaturation in the oil can be determined.
Why can't the iodine value determination sample be weighed directly in the iodine valence flask?
Hello <> oil iodine price determination sample, why can't you directly weigh the price increase bottle in iodine mountain? Iodine value determination of fats and oils is a chemical analysis method used to determine the degree of unsaturation in oils and fats. In this method, it is necessary to add the oil to be tested to the iodine valence bottle, and then add a certain amount of iodine solution.
The iodine will be bound to the unsaturated, and the remaining iodine will then be titrated to the reduction. Depending on the amount of iodine consumed, the degree of unsaturation in the oil can be determined.
Because iodine solution is volatile, and it not only reacts chemically with oils and fats, but also reacts with moisture and carbon dioxide in the atmosphere. Therefore, when performing an iodine valence determination, the sample cannot be weighed directly on the iodine valence flask. This can lead to inaccurate results and may even lead to bridge disruption of the reagent.
Therefore, the sample to be measured needs to be weighed into another dry container before being added to the iodine valence flask to ensure the accuracy of the measurement.
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Anonymous users2024-02-04Yuchen State Answer]: The iodine price of vegetable oil refers to the sign of the degree of unsaturated oil and fat. It is one of the characteristic constants of oils and fats, expressed in grams of iodine that can be absorbed per 100 grams of oil-masking fat.
That liquid should be starch suspension (starch is insoluble in water, so it cannot be said to be a solution), iodine will turn blue immediately when it encounters starch, and the speed is very fast, so starch is the best reagent to test iodine or iodine ions
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