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  2. Empirical formula - Wikipedia

    en.wikipedia.org/wiki/Empirical_formula

    In chemistry, the empirical formula of a chemical compound is the simplest whole number ratio of atoms present in a compound. [1] A simple example of this concept is that the empirical formula of sulfur monoxide, or SO, is simply SO, as is the empirical formula of disulfur dioxide, S 2 O 2.

  3. Chemical formula - Wikipedia

    en.wikipedia.org/wiki/Chemical_formula

    An example of the difference is the empirical formula for glucose, which is CH 2 O (ratio 1:2:1), while its molecular formula is C 6 H 12 O 6 (number of atoms 6:12:6). For water, both formulae are H 2 O. A molecular formula provides more information about a molecule than its empirical formula, but is more difficult to establish.

  4. Formula unit - Wikipedia

    en.wikipedia.org/wiki/Formula_unit

    In most cases the formula representing a formula unit will also be an empirical formula, such as calcium carbonate (CaCO 3) or sodium chloride (NaCl), but it is not always the case. For example, the ionic compounds potassium persulfate ( K 2 S 2 O 8 ), mercury(I) nitrate Hg 2 (NO 3 ) 2 , and sodium peroxide Na 2 O 2 , have empirical formulas of ...

  5. Glossary of chemical formulae - Wikipedia

    en.wikipedia.org/wiki/Glossary_of_chemical_formulae

    Chemical formula Synonyms CAS number CAgO carbonylsilver: CCl 2 F 2: dichlorodifluoromethane freon-12: 75-71-8 CCl 4: carbon tetrachloride tetrachloromethane: 56-23-5 C(CN) 4: tetracyanomethane: 24331-09-7 CFCl 3: trichlorofluoromethane freon-11: 75-69-4 CFCl 2 CF 2 Cl: chlorotrifluoromethane freon-13: 75-72-9 CHCl 3: chloroform ...

  6. Formula - Wikipedia

    en.wikipedia.org/wiki/Formula

    For example, the empirical formula of ethanol may be written C 2 H 6 O, [11] because the molecules of ethanol all contain two carbon atoms, six hydrogen atoms, and one oxygen atom. Some types of ionic compounds, however, cannot be written as empirical formulas which contains only the whole numbers.

  7. 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.

  8. List of unsolved problems in chemistry - Wikipedia

    en.wikipedia.org/wiki/List_of_unsolved_problems...

    Protein folding problem: Is it possible to predict the secondary, tertiary and quaternary structure of a polypeptide sequence based solely on the sequence and environmental information? Inverse protein-folding problem: Is it possible to design a polypeptide sequence which will adopt a given structure under certain environmental conditions?

  9. Bredt's rule - Wikipedia

    en.wikipedia.org/wiki/Bredt's_rule

    In organic chemistry, an anti-Bredt molecule is a bridged molecule with a double bond at the bridgehead. Bredt's rule is the empirical observation that such molecules only form in large ring systems. For example, two of the following norbornene isomers violate Bredt's rule, and are too unstable to prepare: Bridgehead atoms violating Bredt's ...