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  2. Empirical formula - Wikipedia

    en.wikipedia.org/wiki/Empirical_formula

    Glucose (C 6 H 12 O 6), ribose (C 5 H 10 O 5), Acetic acid (C 2 H 4 O 2), and formaldehyde (CH 2 O) all have different molecular formulas but the same empirical formula: CH 2 O.This is the actual molecular formula for formaldehyde, but acetic acid has double the number of atoms, ribose has five times the number of atoms, and glucose has six times the number of atoms.

  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. Chemical formula - Wikipedia

    en.wikipedia.org/wiki/Chemical_formula

    The term empirical refers to the process of elemental analysis, a technique of analytical chemistry used to determine the relative percent composition of a pure chemical substance by element. For example, hexane has a molecular formula of C 6 H 14 , and (for one of its isomers, n-hexane) a structural formula CH 3 CH 2 CH 2 CH 2 CH 2 CH 3 ...

  5. Combustion analysis - Wikipedia

    en.wikipedia.org/wiki/Combustion_analysis

    Combustion analysis is a method used in both organic chemistry and analytical chemistry to determine the elemental composition (more precisely empirical formula) of a pure organic compound by combusting the sample under conditions where the resulting combustion products can be quantitatively analyzed.

  6. Flory–Fox equation - Wikipedia

    en.wikipedia.org/wiki/Flory–Fox_equation

    The Flory–Fox equation relates the number-average molecular weight, M n, to the glass transition temperature, T g, as shown below: =, where T g,∞ is the maximum glass transition temperature that can be achieved at a theoretical infinite molecular weight and K is an empirical parameter that is related to the free volume present in the polymer sample.

  7. Compositional data - Wikipedia

    en.wikipedia.org/wiki/Compositional_data

    In a survey, the proportions of people positively answering some different items can be expressed as percentages. 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.

  8. Elemental analysis - Wikipedia

    en.wikipedia.org/wiki/Elemental_analysis

    Elemental analysis is a process where a sample of some material (e.g., soil, waste or drinking water, bodily fluids, minerals, chemical compounds) is analyzed for its elemental and sometimes isotopic composition.

  9. 68–95–99.7 rule - Wikipedia

    en.wikipedia.org/wiki/68–95–99.7_rule

    In statistics, the 68–95–99.7 rule, also known as the empirical rule, and sometimes abbreviated 3sr, is a shorthand used to remember the percentage of values that lie within an interval estimate in a normal distribution: approximately 68%, 95%, and 99.7% of the values lie within one, two, and three standard deviations of the mean, respectively.