The Hill system (or Hill notation) is a system of writing empirical chemical formulas, molecular chemical formulas and components of a condensed formula such that the number of carbon atoms in a molecule is indicated first, the number of hydrogen atoms next, and then the number of all other chemical elements subsequently, in alphabetical order of the chemical symbols.
Iodine clock reaction. The iodine clock reaction (STd3) is a classical chemical clock demonstration experiment to display chemical kinetics in action; it was discovered by Hans Heinrich Landolt in 1886. Two colourless solutions are mixed and at first there is no visible reaction.
When iodine is added to water, the following reaction results: I 2 (l) + H 2 - (aq) + 2H + (aq) + I - (aq). I 2 molecules and water molecules react to substances such as hypoiodite (OI -). The reaction can move both ways of the equilibrium, depending on the pH of the solution. Iodine may also occur as I 3 - (aq), HIO(aq), IO - (aq) en HIO 3 (aq). Iodine can bind to many different substances, for example other halogens. The compounds that are form behave differently when they come in contact with water. Solubility of iodine and iodine compounds. Water solubility of iodine is determined by temperature (20 o C) and pressure (1 bar), and is relatively low.