enow.com Web Search

Search results

  1. Results from the WOW.Com Content Network
  2. Mass (mass spectrometry) - Wikipedia

    en.wikipedia.org/wiki/Mass_(mass_spectrometry)

    The accurate mass (more appropriately, the measured accurate mass [9]) is an experimentally determined mass that allows the elemental composition to be determined. [10] For molecules with mass below 200 Da , 5 ppm accuracy is often sufficient to uniquely determine the elemental composition.

  3. Prices of chemical elements - Wikipedia

    en.wikipedia.org/wiki/Prices_of_chemical_elements

    As of 2020, the most expensive non-synthetic element by both mass and volume is rhodium. It is followed by caesium, iridium and palladium by mass and iridium, gold and platinum by volume. Carbon in the form of diamond can be more expensive than rhodium. Per-kilogram prices of some synthetic radioisotopes range to trillions of dollars.

  4. Amine value - Wikipedia

    en.wikipedia.org/wiki/Amine_value

    The amine value is useful in helping determine the correct stoichiometry of a two component amine cure epoxy resin system. [6] [7] [8]It is the number of Nitrogens x 56.1 (Mwt of KOH) x 1000 (convert to milligrams) divided by molecular mass of the amine functional compound.

  5. Elemental analysis - Wikipedia

    en.wikipedia.org/wiki/Elemental_analysis

    [citation needed] This information is important to help determine the structure of an unknown compound, as well as to help ascertain the structure and purity of a synthesized compound. In present-day organic chemistry, spectroscopic techniques ( NMR , both 1 H and 13 C), mass spectrometry and chromatographic procedures have replaced EA as the ...

  6. Mass versus weight - Wikipedia

    en.wikipedia.org/wiki/Mass_versus_weight

    In scientific contexts, mass is the amount of "matter" in an object (though "matter" may be difficult to define), but weight is the force exerted on an object's matter by gravity. [1] At the Earth 's surface, an object whose mass is exactly one kilogram weighs approximately 9.81 newtons , the product of its mass and the gravitational field ...

  7. Lever rule - Wikipedia

    en.wikipedia.org/wiki/Lever_rule

    In chemistry, the lever rule is a formula used to determine the mole fraction (x i) or the mass fraction (w i) of each phase of a binary equilibrium phase diagram.It can be used to determine the fraction of liquid and solid phases for a given binary composition and temperature that is between the liquidus and solidus line.

  8. Gravimetric analysis - Wikipedia

    en.wikipedia.org/wiki/Gravimetric_analysis

    Gravimetric analysis describes a set of methods used in analytical chemistry for the quantitative determination of an analyte (the ion being analyzed) based on its mass. The principle of this type of analysis is that once an ion's mass has been determined as a unique compound, that known measurement can then be used to determine the same analyte's mass in a mixture, as long as the relative ...

  9. Avogadro constant - Wikipedia

    en.wikipedia.org/wiki/Avogadro_constant

    The Avogadro constant, commonly denoted N A [1] or L, [2] is an SI defining constant with an exact value of 6.022 140 76 × 10 23 mol −1 (reciprocal moles). [3] [4] It defines the number of constituent particles in one mole, where the particles in question can be either molecules, atoms, ions, ion pairs, or any other elementary entities.