Why do atoms take part in bonding?
Atoms form chemical bonds to make their outer electron shells more stable. An ionic bond, where one atom essentially donates an electron to another, forms when one atom becomes stable by losing its outer electrons and the other atoms become stable (usually by filling its valence shell) by gaining the electrons.
Can nitrogen form double bonds?
The chemistry of nitrogen is dominated by the ease with which nitrogen atoms form double and triple bonds. A neutral nitrogen atom contains five valence electrons: 2s2 2p3. double bond. The strength of the nitrogen-nitrogen triple bond makes the N2 molecule very unreactive.
How do you calculate iodine value?
Iodine values are most commonly calculated using a regression equation based on fatty acid concentrations: iodine value (IV)=16:1 (0.95)+18:1 (0.86)+18:2 (1.732)+18:3 (2.616)+20:1 (0.785)+22:1 (0.723).
What is the normal range of iodine value?
The iodine-replete healthy adult has about 15–20 mg of iodine, 70%–80% of which is contained in the thyroid [6]. Median urinary iodine concentrations of 100–199 mcg/L in children and adults, 150–249 mcg/L in pregnant women and >100 mcg/L in lactating women indicate iodine intakes are adequate [3].
What is the importance of iodine value?
The most important application of the iodine value is to determine the amount of unsaturation contained in fatty acids. This unsaturation is in the form of double bonds which react with iodine compounds. The higher the iodine value, the more unsaturated fatty acid bonds are present in a fat.
Why starch is used as indicator in iodine value analysis?
In an iodometric titration, a starch solution is used as an indicator since it can absorb the I2 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.
Why is starch a good indicator?
Starch reacts with Iodine in the presence of Iodide ion to form an intensely colored blue complex, which is visible at very low concentrations of Iodine, making it a very good indicator in both direct and indirect lodometric titrations.
Why is iodine a indicator?
Iodine is known as an indicator because it changes color in the presence of starch and several other molecules. Iodine can also be used to track iodide and iodine in its elemental form. Elmhurst College describes iodine as a crucial indicator that is used in several different tests.
What is the starch indicator?
Starch. The iodine–starch test is a chemical reaction that is used to test for the presence of starch or for iodine. The combination of starch and iodine is intensely blue-black.
Is Iodine a starch indicator?
Using iodine to test for the presence of starch is a common experiment. A solution of iodine (I2) and potassium iodide (KI) in water has a light orange-brown color. If it is added to a sample that contains starch, such as the bread pictured above, the color changes to a deep blue.
How do you make a 1% starch solution?
** To prepare the 1% starch solution, mix 1 / 2 teaspoon of soluble starch (cornstarch or potato starch) with a small amount of water. Stir this mixture into 100mL of boiling distilled water. Boil for 1 minute and then cool. Put in marked dropper bottle.
What is the purpose of adding the 2% starch solution?
Starch is a viable indicator in the titration process because it turns deep dark blue when iodine is present in a solution. When starch is heated in water, decomposition occurs and beta-amylose is produced.
Why starch is freshly prepared?
When starch is heated in water, various decomposition products are formed, among which is beta-amylose which forms a deep blue-black complex with iodine. The starch indicator solution must be freshly prepared since it will decompose and its sensitivity is decreased.