Acid-free paper Acid-free paper Acid-free paper is paper that if infused in water yields a neutral or basic pH (7 or slightly greater). It can be made from any cellulose fiber as long as the active acid pulp is eliminated during processing. It is also lignin- and sulfur-free. Acid-free paper addresses the problem of preserving documents and artwork for long periods. Paper made from wood-based pulp that has not had its lignin removed turns yellow, becomes brittle, and deteriorates over time. When exposed to light and/or heat, the molecules in the acidic paper will break down even faster. Acidic wood-pulp paper became
Acid dissociation constant much weaker base than water. Compare this reaction with what happens when acetic acid is dissolved in the more acidic solvent pure sulfuric acid The unlikely geminal diol species is stable in these environments. For aqueous solutions the pH scale is the most convenient acidity function. Other acidity functions have been proposed for non-aqueous media, the most notable being the Hammett acidity function, "H", for superacid media and its modified version "H" for superbasic media. In aprotic solvents, oligomers, such as the well-known acetic acid dimer, may be formed by hydrogen bonding. An acid may also form hydrogen bonds to