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  2. Parts-per notation - Wikipedia

    en.wikipedia.org/wiki/Parts-per_notation

    In fractions like "2 nanometers per meter" (2 n m / m = 2 nano = 2×10 −9 = 2 ppb = 2 × 0.000 000 001), so the quotients are pure-number coefficients with positive values less than or equal to 1. When parts-per notations, including the percent symbol (%), are used in regular prose (as opposed to mathematical expressions), they are still pure ...

  3. Mass fraction (chemistry) - Wikipedia

    en.wikipedia.org/wiki/Mass_fraction_(chemistry)

    Mass fraction can also be expressed, with a denominator of 100, as percentage by mass (in commercial contexts often called percentage by weight, abbreviated wt.% or % w/w; see mass versus weight). It is one way of expressing the composition of a mixture in a dimensionless size ; mole fraction (percentage by moles , mol%) and volume fraction ...

  4. Compositional data - Wikipedia

    en.wikipedia.org/wiki/Compositional_data

    As the total amount is identified as 100, the compositional vector of D components can be defined using only D − 1 components, assuming that the remaining component is the percentage needed for the whole vector to add to 100.

  5. Composition of matter - Wikipedia

    en.wikipedia.org/wiki/Composition_of_matter

    The Chakrabarty Court said that "we must determine whether respondent's micro-organism constitutes a 'manufacture' or 'composition of matter' within the meaning of the statute. [8] The Court's answer to its question was yes----"respondent's micro-organism plainly qualifies as patentable subject matter." [9] But the Court never said which one it ...

  6. Stoichiometry - Wikipedia

    en.wikipedia.org/wiki/Stoichiometry

    For example, in the reaction CH 4 + 2 O 2 → CO 2 + 2 H 2 O, the stoichiometric number of CH 4 is −1, the stoichiometric number of O 2 is −2, for CO 2 it would be +1 and for H 2 O it is +2. In more technically precise terms, the stoichiometric number in a chemical reaction system of the i-th component is defined as

  7. Mole fraction - Wikipedia

    en.wikipedia.org/wiki/Mole_fraction

    When expressed in percent, it is known as the mole percent or molar percentage (unit symbol %, sometimes "mol%", equivalent to cmol/mol for 10 −2). The mole fraction is called amount fraction by the International Union of Pure and Applied Chemistry (IUPAC) [ 1 ] and amount-of-substance fraction by the U.S. National Institute of Standards and ...

  8. Atomic ratio - Wikipedia

    en.wikipedia.org/wiki/Atomic_ratio

    A closely related concept is the atomic percent (or at.%), which gives the percentage of one kind of atom relative to the total number of atoms. [1] The molecular equivalents of these concepts are the molar fraction , or molar percent .

  9. Law of definite proportions - Wikipedia

    en.wikipedia.org/wiki/Law_of_definite_proportions

    The law of definite proportion was given by Joseph Proust in 1797. [2]I shall conclude by deducing from these experiments the principle I have established at the commencement of this memoir, viz. that iron like many other metals is subject to the law of nature which presides at every true combination, that is to say, that it unites with two constant proportions of oxygen.