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Historically, the mole was defined as the amount of substance in 12 grams of the carbon-12 isotope.As a consequence, the mass of one mole of a chemical compound, in grams, is numerically equal (for all practical purposes) to the mass of one molecule or formula unit of the compound, in daltons, and the molar mass of an isotope in grams per mole is approximately equal to the mass number ...
The tables below provides information on the variation of solubility of different substances (mostly inorganic compounds) in water with temperature, at one atmosphere pressure. Units of solubility are given in grams of substance per 100 millilitres of water (g/(100 mL)), unless shown otherwise.
One litre of liquid water has a mass of almost exactly one kilogram, due to the gram being defined in 1795 as one cubic centimetre of water at the temperature of melting ice. [4] The original decimetre length was 44.344 lignes, which was revised in 1798 to 44.3296 lignes. This made the original litre 1.000 974 of today's cubic decimetre. It was ...
The ideal gas equation can be rearranged to give an expression for the molar volume of an ideal gas: = = Hence, for a given temperature and pressure, the molar volume is the same for all ideal gases and is based on the gas constant: R = 8.314 462 618 153 24 m 3 ⋅Pa⋅K −1 ⋅mol −1, or about 8.205 736 608 095 96 × 10 −5 m 3 ⋅atm⋅K ...
1 micrometer (also called 1 micron) 1–4 μm Typical length of a bacterium [22] 4 μm Typical diameter of spider silk [23] 7 μm Typical size of a red blood cell [24] 10 −5: 10 μm: 10 μm Typical size of a fog, mist, or cloud water droplet 10 μm Width of transistors in the Intel 4004, the world's first commercial microprocessor: 12 μm
Volume fraction, which is widely used in chemistry (commonly denoted as v/v), is defined as the volume of a particular component divided by the sum of all components in the mixture when they are measured separately. For example, to make 100 mL of 50% alc/vol ethanol solution, water would be added to 50 mL of ethanol to make up exactly 100 mL.
A pure stoichiometric mixture may be obtained by water electrolysis, which uses an electric current to dissociate the water molecules: Electrolysis: 2 H 2 O → 2 H 2 + O 2 Combustion: 2 H 2 + O 2 → 2 H 2 O. William Nicholson was the first to decompose water in this manner in 1800.
The optimal concentration varies by food; in clear soup, the "pleasure score" rapidly falls with the addition of more than one gram of MSG per 100 mL. [14] The sodium content (in mass percent) of MSG, 12.28%, is about one-third of that in sodium chloride (39.34%), due to the greater mass of the glutamate counterion. [15]