The formula weight is simply the weight in atomic mass units of all the atoms in a given formula.Formula weights are especially useful in determining the relative weights of reagents and products in a chemical reaction. The molar mass and molecular weight of C2H5OH(H) is 47.07638. Explanation of how to find the molar mass of C2H5OH : Ethanol. Definitions of molecular mass, molecular weight, molar mass and molar weight Molar mass of C2H5OH = 46.06844 g/mol. When calculating molecular weight of a chemical compound, it tells us how many grams are in one mole of that substance. The molar mass and molecular weight of C2H6O - C2H5OH is 46,068. of a chemical compoundMore information on molar mass and molecular weight ›› C2H5OH molecular weight. These relative weights computed from the chemical equation are sometimes called equation weights.If the formula used in calculating molar mass is the molecular formula, the formula weight computed is the molecular weight. A few things to consider when finding the molar mass for C2H5OH : - make sure you have the correct chemical formula. This is how to calculate molar mass (average molecular weight), which is based on isotropically weighted averages. Molecular weight calculation: 12.0107*2 + 1.00794*5 + 15.9994 + 1.00794 ›› Percent composition by element For bulk stoichiometric calculations, we are usually determining molar mass, which may also be called standard atomic weight or average atomic mass.Finding molar mass starts with units of grams per mole (g/mol). Examples of molecular weight computations: C[14]O[16]2, S[34]O[16]2. Computing molecular weight (molecular mass) To calculate molecular weight of a chemical compound enter it's formula, specify its isotope mass number after each element in square brackets. This is not the same as molecular mass, which is the mass of a single molecule of well-defined isotopes. In chemistry, the formula weight is a quantity computed by multiplying the atomic weight (in atomic mass units) of each element in a chemical formula by the number of atoms of that element present in the formula, then adding all of these products together.The atomic weights used on this site come from NIST, the National Institute of Standards and Technology. Convert grams C2H5OH to moles or moles C2H5OH to grams. The percentage by weight of any atom or group of atoms in a compound can be computed by dividing the total weight of the atom (or group of atoms) in the formula by the formula weight and multiplying by 100.Using the chemical formula of the compound and the periodic table of elements, we can add up the atomic weights and calculate molecular weight of the substance.Calculate the molecular weight We use the most common isotopes.