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  2. Sodium amide - Wikipedia

    en.wikipedia.org/wiki/Sodium_amide

    Sodium amide, commonly called sodamide (systematic name sodium azanide), is the inorganic compound with the formula NaNH 2. It is a salt composed of the sodium cation and the azanide anion. This solid, which is dangerously reactive toward water, is white, but commercial samples are typically gray due to the presence of small quantities of ...

  3. Amount of substance - Wikipedia

    en.wikipedia.org/wiki/Amount_of_substance

    The molar mass of a substance depends not only on its molecular formula, but also on the distribution of isotopes of each chemical element present in it. For example, the molar mass of calcium-40 is 39.962 590 98 (22) g/mol , whereas the molar mass of calcium-42 is 41.958 618 01 (27) g/mol , and of calcium with the normal isotopic mix is 40.078 ...

  4. 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 ...

  5. Nitrogen - Wikipedia

    en.wikipedia.org/wiki/Nitrogen

    Nitrogen is the most common pure element in the earth, making up 78.1% of the volume of the atmosphere [9] (75.5% by mass), around 3.89 million gigatonnes (3.89 × 10 18 kg). Despite this, it is not very abundant in Earth's crust, making up somewhere around 19 parts per million of this, on par with niobium , gallium , and lithium .

  6. Gas composition - Wikipedia

    en.wikipedia.org/wiki/Gas_composition

    The Gas composition of any gas can be characterised by listing the pure substances it contains, and stating for each substance its proportion of the gas mixture's molecule count.Nitrogen N 2 78.084 Oxygen O 2 20.9476 Argon Ar 0.934 Carbon Dioxide CO 2 0.0314

  7. Labeling of fertilizer - Wikipedia

    en.wikipedia.org/wiki/Labeling_of_fertilizer

    More precisely, the first number ("N value") is the percentage of elemental nitrogen by weight in the fertilizer; that is, the mass fraction of nitrogen times 100. The second number ("P value") is the percentage by weight of phosphorus pentoxide P 2 O 5. The third number ("K value") is the equivalent content of potassium oxide K 2 O. [3] For ...

  8. Chemical formula - Wikipedia

    en.wikipedia.org/wiki/Chemical_formula

    A chemical formula identifies each constituent element by its chemical symbol and indicates the proportionate number of atoms of each element. In empirical formulae, these proportions begin with a key element and then assign numbers of atoms of the other elements in the compound, by ratios to the key element.

  9. Chemical symbol - Wikipedia

    en.wikipedia.org/wiki/Chemical_symbol

    A few isotopes have their own specific symbols rather than just an isotopic detail added to their element symbol. Attached subscripts or superscripts specifying a nuclide or molecule have the following meanings and positions: The nucleon number (mass number) is shown in the left superscript position (e.g., 14 N). This number defines the ...