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In science and engineering, the parts-per notation is a set of pseudo-units to describe small values of miscellaneous dimensionless quantities, e.g. mole fraction or mass fraction. Since these fractions are quantity-per-quantity measures, they are pure numbers with no associated units of measurement. Commonly used are parts-per-million (ppm, 10 ...
The partition coefficient, abbreviated P, is defined as a particular ratio of the concentrations of a solute between the two solvents (a biphase of liquid phases), specifically for un- ionized solutes, and the logarithm of the ratio is thus log P. [10]: 275ff When one of the solvents is water and the other is a non-polar solvent, then the log P ...
Stoichiometry (/ ˌstɔɪkiˈɒmɪtri /) is the relationships among the weights of reactants and products before, during, and following chemical reactions. Stoichiometry is founded on the law of conservation of mass where the total mass of the reactants equals the total mass of the products, leading to the insight that the relations among ...
Law of multiple proportions. In chemistry, the law of multiple proportions states that in compounds which contain two particular chemical elements, the amount of Element A per measure of Element B will differ across these compounds by ratios of small whole numbers. For instance, the ratio of the hydrogen content in methane (CH 4) and ethane (C ...
In chemistry, the mole fraction or molar fraction, also called mole proportion or molar proportion, is a quantity defined as the ratio between the amount of a constituent substance, ni (expressed in unit of moles, symbol mol), and the total amount of all constituents in a mixture, ntot (also expressed in moles): [1] It is denoted xi (lowercase ...
In chemistry, the law of definite proportions, sometimes called Proust's law or the law of constant composition, states that a given chemical compound always contains its component elements in a fixed ratio (by mass) and does not depend on its source or method of preparation. For example, oxygen makes up about 8 / 9 of the mass of any sample of ...
Chemical impurity. In chemistry and materials science, impurities are chemical substances inside a confined amount of liquid, gas, or solid. They differ from the chemical composition of the material or compound. [1] Firstly, a pure chemical should appear in at least one chemical phase and can also be characterized by its phase diagram.
The par value of stock has no relation to market value and, as a concept, is somewhat archaic. [when?] The par value of a share is the value stated in the corporate charter below which shares of that class cannot be sold upon initial offering; the issuing company promises not to issue further shares below par value, so investors can be confident that no one else will receive a more favorable ...