Category: Simplified Chemistry

A low-density porous trans­parent material that consists of more than 90% air. Usually based on metal oxides or silica, aerogels are used as drying agents and insulators.

adsorption isotherm An equation that describes how the amount of a substance adsorbed onto a surface de­pends on its pressure (if a gas) or its concentration (if in a solution), at a constant temperature. Several ad­sorption isotherms are used in sur­face chemistry including the BET isotherm and the Langmuir ad­sorption isotherm. The different isotherms correspond

adsorption indicator (absorption indicator) A type of indicator used in reactions that involve precipita­tion. The yellow dye fluorescein is a common example, used for the reac­tion NaCl(aq) + AgNO3(aq) → AgCl(s) + NaNO3(aq) As silver nitrate solution is added to the sodium chloride, silver chlo­ride precipitates. As long as Cl” ions are in excess, they