Barium is a soft, silvery alkaline earth metal with atomic number 56. Never found naturally as free element, mainly in minerals barite and witherite. Discovered in 1772, first isolated by Davy in 1808 through electrolysis
Nitrite ion (NO−2) has symmetrical structure with equal N–O bonds. Nitrite is Lewis base and conjugate base of weak acid nitrous acid. Nitrite can be oxidized to +4 and +5 or reduced to −3
PVP is a water-soluble polymer made from N-vinylpyrrolidone monomer. First synthesized by BASF chemist Walter Reppe in 1939. Soluble in water and other polar solvents. Absorbs up to 40% of its weight in atmospheric water
Chalk is a soft, white, porous sedimentary carbonate rock. Composed mainly of calcite fragments from plankton skeletons. Contains 2-4% other minerals, mainly quartz and clay. Has porosity ranging from 35-47%
Acetate is formed by combining acetic acid with a base. Acetate ion has formula C2H3O−2 or CH3COO−. Common abbreviations include OAc−, AcO−, HOAc, NaOAc, EtOAc
Mineral oil is a colorless, odorless liquid derived from petroleum distillates. Composed mainly of alkanes and cycloalkanes, with a density of 0.8-0.87 g/cm³. First used as "mineral oil" in 1771, with various imprecise names