empirical formula

Examples of empirical formula in the following topics:

• Molecular Formulas

  • In this case, the empirical formula of glucose is CH2O.
  • To convert between empirical and molecular formulas, the empirical formula can be multiplied by a whole number to reach the molecular formula.
  • In this case, the empirical formula would be multiplied by 6 to get to the molecular formula.
  • The compound dichlorine hexoxide has an empirical formula ClO3 and the molecular formula Cl2O6
  • The compound hydrogen peroxide has the empirical formula HO and the molecular formula H2O2

• Empirical Formulas

  • The molecular formula for a compound is equal to, or a whole-number multiple of, its empirical formula.
  • The empirical formula is the lowest possible whole-number ratio of the elements.
  • The empirical formula of decane is C5H11.
  • Therefore, if the empirical formula of decane is C5H11, the molecular formula of decane is twice that, or C10H22.
  • This video shows how to go from the molecular formula of a compound to its corresponding empirical formula.

• Polyatomic Molecules

  • A molecule's chemical formula and structure are the two important factors that determine its properties, particularly reactivity.
  • A compound's empirical formula is the simplest integer ratio of its constitutional chemical elements.
  • For example, carbohydrates have the same ratio (carbon: hydrogen: oxygen = 1:2:1) and thus the same empirical formula, but have different total numbers of atoms in the molecule.
  • The molecular formula characterizes different molecules by reflecting their exact number of compositional atoms.
  • The empirical formula is often the same as the molecular formula, but not always; for example, the molecule acetylene has molecular formula C2H2, but the simplest integer ratio of elements is CH.

• Molecules

  • Often, a compound's composition can also be denoted by an empirical formula, which is the simplest integer ratio of its constituent chemical elements.
  • However, this empirical formula does not always describe the specific molecule in question, since it provides only the ratio of its elements.
  • The full elemental composition of a molecule can be precisely represented by its molecular formula, which indicates the exact number of atoms that are in the molecule.
  • The chemical formula for propanol (C3H7OH) describes several different molecules, which vary by the position of the alcohol (OH).

• Formulas of Ionic Compounds

  • Ionic solids are typically represented by their empirical formulas.
  • The complete formula for an ionic compound can be determined by satisfying two conditions:
  • Its ionic formula is written as CaCl2, the neutral combination of these ions.
  • For example, the hydroxide ion has the formula OH-1.
  • Generate the empirical formula of an ionic compound given its molecular constituents.

• Percent Composition of Compounds

  • The atomic composition of chemical compounds can be described using a variety of notations including molecular, empirical, and structural formulas.
  • For example, butane has a molecular formula of C4H10.
  • Mass percents can be determined experimentally via elemental analysis, and these values can be used to calculate the empirical formula of unknown compounds.
  • However, this information is insufficient to determine the molecular formula without additional information on the compound's molecular weight.
  • Translate between a molecular formula of a compound and its percent composition by mass

• Combustion Analysis

  • Combustion analysis is commonly used to analyze samples of unknown chemical formula.
  • The data and the ratios can then be used to calculate the empirical formula of the unknown sample.

• Formulas of Ionic Compounds

  • Ionic formulas must satisfy the noble gas configurations for the constituent ions and the product compound must be electrically neutral.
  • In addition, though any ratio of 2 bromine atoms to 1 magnesium atom will satisfy the two requirements above, the formula for ionic compounds is typically presented as the empirical formula, or the simplest whole-number ratio of atoms with positive integers.
  • Note that the cation always precedes the anion both in written form and in formulas.
  • A lesson on writing formulas for binary ionic compounds as well as ionic compounds containing polyatomic ions.
  • Apply knowledge of ionic bonding to predict the formula of ionic compounds

• A Structure Formula Relationship

  • Recall that the molecular formula of a hydrocarbon (CnHm) provides information about the number of rings and/or double bonds that must be present in its structural formula.
  • In the formula shown below a triple bond is counted as two double bonds.
  • This molecular formula analysis may be extended beyond hydrocarbons by a few simple corrections.
  • All halogens present in the molecular formula must be replaced by hydrogen.
  • Each nitrogen in the formula must be replaced by a CH moiety.

• Expansion Throughout Central and Western Asia

  • The Mongol Empire conquered the Kara-Khitan Khanate, an empire of formerly nomadic people in Central Asia, in the years 1216-1218 CE.
  • Genghis Khan saw the potential advantage in Khwarazmia as a commercial trading partner using the Silk Road, and he sent a caravan to establish official trade ties with the empire.
  • Before he left, he divided his empire among his sons and immediate family and declared that his heir should be his charismatic third son, Ögedei.
  • By the time of Genghis Khan's death in 1227, the Mongol Empire ruled from the Pacific Ocean to the Caspian Sea, an empire twice the size of the Roman Empire and Muslim Caliphate.
  • The earliest known written formula for gunpowder, from the Chinese Wujing Zongyao, a military compendium, of 1044 CE.