Now, compute the sum of products of number of atoms to the atomic weight: Molar mass (H 2 SO 4) Count i Weight i. Then, lookup atomic weights for each element in periodic table: H: 1.00794, S: 32.065, O: 15.9994. For bulk stoichiometric calculations, we are usually determining molar mass, which may also be called standard atomic weight or average atomic mass. First, compute the number of each atom in H 2 SO 4: H: 2, S: 1, O: 4. This is not the same as molecular mass, which is the mass of a single molecule of well-defined isotopes. This is how to calculate molar mass (average molecular weight), which is based on isotropically weighted averages. The atomic weights used on this site come from NIST, the National Institute of Standards and Technology. 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.
These relative weights computed from the chemical equation are sometimes called equation weights. SOLUTION Using the periodic table, find the molar mass of CuSO4. This site explains how to find molar mass.įormula weights are especially useful in determining the relative weights of reagents and products in a chemical reaction. The reason is that the molar mass of the substance affects the conversion. See also our theoretical yield calculator for chemical reactions (probably your next stop to finish the problem set). To complete this calculation, you have to know what substance you are trying to convert. The molar mass of CuSO4 (Copper sulfate) is: 159.602 grams/mol. molecular formula cuso4.XH2o mass of crucible+ hydrate35. Show calculations hydrate copper sulphate. Show calculations c) calculate the number of moles of water in cuso4. 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.Ī common request on this site is to convert grams to moles. A)Calculate the formula mass/molar mass of the anhydrous salt of cuso4 b) calculate the number of moles of the anhydrous salt. If the formula used in calculating molar mass is the molecular formula, the formula weight computed is the molecular weight. The formula weight is simply the weight in atomic mass units of all the atoms in a given formula. When calculating molecular weight of a chemical compound, it tells us how many grams are in one mole of that substance. The pentahydrate (n 5), a bright blue crystal, is the most commonly encountered hydrate of copper(II) sulfate, while its anhydrous form is white. 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.įinding molar mass starts with units of grams per mole (g/mol).