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The volume of a particular material or compound is affected by ambient moisture and may be considered its coefficient of hygroscopic expansion (CHE) (also referred to as CME, or coefficient of moisture expansion) or the coefficient of hygroscopic contraction (CHC)—the difference between the two terms being a difference in sign convention.
Here, a primary standard is typically a reagent which can be weighed easily, and which is so pure that its weight is truly representative of the number of moles of substance contained. Features of a primary standard include: High purity; Stability (low reactivity) Low hygroscopicity (to minimize weight changes due to humidity)
4,4′-Bipyridine (abbreviated to 4,4′-bipy or 4,4′-bpy) is an organic compound with the formula (C 5 H 4 N) 2. It is one of several isomers of bipyridine. It is a colorless solid that is soluble in organic solvents. is mainly used as a precursor to N,N′-dimethyl-4,4′-bipyridinium [(C 5 H 4 NCH 3) 2] 2+, known as paraquat.
Hydroxylammonium nitrate or hydroxylamine nitrate (HAN) is an inorganic compound with the chemical formula [NH 3 OH] + [NO 3] −. It is a salt derived from hydroxylamine and nitric acid. In its pure form, it is a colourless hygroscopic solid. It has potential to be used as a rocket propellant either as a solution in monopropellants or ...
More modern isotherms showing the sorption of water vapor, on the vertical axis, provide the ratio of the weight of water adsorbed divided by its dry weight, or that ratio converted into a percentage. On the horizontal axis they provide relative humidity or water activity of the air presented to the material.
Choline bitartrate is an organic compound with the chemical formula [(CH 3) 3 NCH 2 CH 2 OH] + HOOC−CH(OH)−CH(OH)−COO −. It is a white crystalline powder with an acid taste. [ 1 ] It is hygroscopic when exposed to air. [ 1 ]
Example 2: Consider a larger block of the same stone material as in Example 1 but with a 1-liter cavity inside of the same amount of stone. The block would still weigh 3 kilograms on dry land (ignoring the weight of air in the cavity) but it would now displace 2 liters of water so its immersed weight would be only 1 kilogram (at 4 °C).
Flat boat dish is an oblong, flat-bottomed dish, in which it is easy to weigh out the substance, and then move it the reaction chamber, but is not recommended for hygroscopic or air-reactive samples. A tall-shaped dish - it is elongated, oblong, flat-bottomed dish, used when the solid is transferred without a funnel. Other types