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
Dry ice color show is mixed together with the alkali present in the solution, the solution, overall, becomes neutral. HCO + H + NH + OH NH + HCO + HO (addition of ammonia) HCO + H + Na + OH Na + HCO + HO (addition of sodium hydroxide) The color of the solution changes due to the universal indicator, a pH detector. Once the alkali-to-acid universal indicator is incorporated into the solution, the color of the solution changes corresponding to the acidic color of the universal indicator. The color of ammonia and water only is green. However, once the dry ice is