Iodine changing

Equip a 500 ml. three necked flask with a reflux condenser, a mercury-sealed mechanical stirrer and separator funnel, and support it on a water bath. Attach an absorption device (Fig. II, 8, 1, c) to the top of the condenser (1). Place 134 g. (152 ml.) of A.R, benzene and 127 g. of iodine in the flask, and heat the water bath to about 50° add 92 ml. of fuming nitric acid, sp. gr. 1-50, slowly from the separatory funnel during 30 minutes. Oxides of nitrogen are evolved in quantity. The temperature rises slowly without the application of heat until the mixture boils gently. When all the nitric acid has been introduced, reflux the mixture gently for 15 minutes. If iodine is still present, add more nitric acid to the warm solution until the purple colour (due to iodine) changes to brownish-red. 

In dry gaseous mixtures the order of activity of the non-metals is somewhat altered, oxygen moving up ahead of bromine and chlorine, and sulphur and iodine changing places F, 0, Cl, Br, S, I. 

The oxidation number of iodine changes from — 1 to 0. Iodide ions are mostly added in the form of potassium iodide KI. Reductions with I- are e.g. ... 

Iodine is one of the most striking and beautiful of all elements. As a solid, it is a heavy, grayish-black, metallic-looking material. When heated, it does not melt. Instead, it sublimes. Sublimation is the process by which a solid turns direcdy to a gas without first melting. The resulting iodine vapor has a violet color and a harsh odor. If a cold object, such as an iron bar, is placed in these vapors, iodine changes back to a solid. It forms attractive, delicate, metallic crystals. 

As the outdoor temperature increases, the iodine changes from a solid directly to a gas. 

The oxidation number of iodine changes from +5 to 0 and the oxidation number of carbon changes from +2 to +4. Iodine is reduced carbon is oxidized. 

The reaction between iodine and propanone shows zero-order kinetics with respect to iodine. Changing the concentration of iodine has no effect on the rate of the reaction. The chemical equation for the reaction is ... 

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