To determine the iodine value of a given sample of oil.
Iodine value is a measure of the degree of unsaturation of an oil.It is defined as the number of parts by mass of iodine absorbed by 100 parts by mass of an oil or fat.
Hanus solution( iodine monobromide), freshly prepared starch solution, carbon tetrachloride,10% solution of potassium iodide, standard sodium thiosulphate solution N/10
Iodine flasks, burette, measuring cylinder
- About 0.2 g of oil is weighed out into a clean dry iodine flask of 500ml capacity.
- It is then dissolved in about 10ml of carbon tetrachloride.
- 25ml of hanus solution is added to it from a burette.
- The flask is gently rotated to mix the contents thoroughly.
- The tip of the flask is moistened with potassium iodide.
- The flask is kept in the dark for half an hour.
- Then 20ml of 10% potassium iodide solution are added & the mixture diluted by adding 200ml of water.
- The mixture is then titrated with standard thiosulphate solution using starch as indicator.
- A blank is also determined.