Until recently, it was used as a refrigerant. 069 amuĬalculate the molecular mass of trichlorofluoromethane, also known as Freon-11, whose condensed structural formula is CCl 3F. 9994 amu C 2 H 6 O molecular mass of ethanol = 46.
The same calculation can also be done in a tabular format, which is especially helpful for more complex molecules: 2C (2 atoms)(12. 9994 amu atom ) = 15.9994 amuĬ Adding together the masses gives the molecular mass: 24.022 amu + 6.0474 amu + 15.9994 amu = 46.069 amuĪlternatively, we could have used unit conversions to reach the result in one step, as described in Essential Skills 2 ( Section 3.7 "Essential Skills 2"): + + = 46.069 amu 011 amu atom ) = 24.022 amu 6 × atomic mass of hydrogen = 6 atoms ( 1. Among its many uses, ethanol is a fuel for internal combustion engines.Ī Determine the number of atoms of each element in the molecule.ī Obtain the atomic masses of each element from the periodic table and multiply the atomic mass of each element by the number of atoms of that element.Ĭ Add together the masses to give the molecular mass.Ī The molecular formula of ethanol may be written in three different ways: CH 3CH 2OH (which illustrates the presence of an ethyl group, CH 3CH 2−, and an −OH group), C 2H 5OH, and C 2H 6O all show that ethanol has two carbon atoms, six hydrogen atoms, and one oxygen atom.ī Taking the atomic masses from the periodic table, we obtain 2 × atomic mass of carbon = 2 atoms ( 12. The average mass of a monatomic ion is the same as the average mass of an atom of the element because the mass of electrons is so small that it is insignificant in most calculations.Ĭalculate the molecular mass of ethanol, whose condensed structural formula is CH 3CH 2OH. Because a molecule or a polyatomic ion is an assembly of atoms whose identities are given in its molecular or ionic formula, we can calculate the average atomic mass of any molecule or polyatomic ion from its composition by adding together the masses of the constituent atoms. Although the mass number is unitless, it is assigned units called atomic mass units (amu). The mass number is an integer that is approximately equal to the numerical value of the atomic mass. To calculate the molecular mass of a covalent compound and the formula mass of an ionic compound and to calculate the number of atoms, molecules, or formula units in a sample of a substance.Īs you learned in Chapter 1 "Introduction to Chemistry", the mass number is the sum of the numbers of protons and neutrons present in the nucleus of an atom.a pollution of 1 gram of benzene in a certain amount of water converts to N A/78.11≈ 7. Using the above calculator you could find that e.g. Or 1 mole of a substance will contain Avogadro's number of that substance. The term " mole" is defined in that one mole of a substance with a molecular (or atomic) mass of one (1), will have a mass of 1 gram. It is defined to be 1/12 of the mass of one atom of carbon-12 and in older works is also abbreviated as "amu".Īlso, important in this field is Avogadro's number (N A) or Avogadro's constant (6.0221 x 10 23). In related terms, another unit of mass often used is Dalton (Da) or unified atomic mass unit (u) when describing atomic masses and molecular masses.
Molecular mass or molar mass are used in stoichiometry calculations in chemistry. This Calculator has been tested on Internet Explorer version 6 only,įirefox might not show all fields correctly. For question or remarks please contact us. !!! Lenntech BV cannot be held responsible for errors in the calculation, Make sure you enter the molecule of crystallization at last (e.g. The calculator handles at most two different bracket levels. The molecular mass calculator will recognize the entered formula's, which are included in the list of organic compounds. Or you can choose by one of the next two option-lists, which contains a series of common organic compounds (including their chemical formula) and all the elements. This online calculator you can use for computing the average molecular weight (MW) of molecules by entering the chemical formulas (for example C3H4OH(COOH)3 ). Molecular Weight Calculator Molecular Weight Calculator