Please let us know how we can improve this web app. Related: Molecular weights of amino acids Weights of atoms and isotopes are from NIST article. Molar mass ( molar weight) is the mass of one mole of a substance and is expressed in g/mol.(1 u is equal to 1/12 the mass of one atom of carbon-12) Molecular mass ( molecular weight) is the mass of one molecule of a substance and is expressed in the unified atomic mass units (u).To calculate molecular weight of a chemical compound enter it's formula, specify its isotope mass number after each element in square brackets.Įxamples of molecular weight computations:ĭefinitions of molecular mass, molecular weight, molar mass and molar weight Molar mass calculator also displays common compound name, Hill formula, elemental composition, mass percent composition, atomic percent compositions and allows to convert from weight to number of moles and vice versa.Ĭomputing molecular weight (molecular mass) Functional groups: D, Ph, Me, Et, Bu, AcAc, For, Ts, Tos, Bz, TMS, tBu, Bzl, Bn, Dmg.Capitalize the first letter in chemical symbol and use lower case for the remaining letters: Ca, Fe, Mg, Mn, S, O, H, C, N, Na, K, Cl, Al. The calculation from the mass of Al to the mass of alum could be done in a single step ( Help Me).Al(s) + H 2SO 4(aq) = Al 2(SO 4) 3(aq) + H 2(g)Ĭomputing molar mass (molar weight)To calculate molar mass of a chemical compound enter its formula and click 'Compute'. Your result should be 35.1% to the correct number of significant figures, although this would often only reported as 35% ( Help Me). This is the theoretical yield. CAUTION! the molar mass of alum includes K, Al, S and O and the twelve H2O! You should get 8.351 g of alum ( Help Me).ĭetermine the percent yield. You should have found that the reaction could form 0.01750moles of alum ( Help Me).Ĭalculate the mass of alum (in grams) from moles of alum. Now convert moles of Al to moles of alum using the stoichiometric factor from the balanced chemical equation. You should get 0.01750 moles of Al ( Help Me). For example, suppose we have the balanced chemical equation: 2Al + 3Cl 2 2AlCl 3. Note that throughout this page extra insignificant figures carried along in the calculation to prevent rounding errors.įirst, we must determine the moles of Al in 0.475 g of Al. , where we start with a given number of moles of a substance and calculate the mass of another substance involved in the chemical equation, or vice versa. Let’s assume that we used 0.475 g of Al and that we obtained 2.930 g of alum. Since we do not need to determine the limiting reagent, our first step is to determine the amount of alum that can theoretically be formed from the amount of Al that we have.

Molar mass: 1 mol CH 4 16.0 g Conversion factors: 16.0 g CH 4 and 1 mole CH 4 1 mole CH 4 16. Example: Write molar mass factors for methane, CH 4,used in gas stoves and gas heaters. relate grams and moles of an element or compound. To simplify things we have told you that the Al is the limiting reagent (if you wish, you can check this). Molar mass conversion factors are written from molar mass. The percent yield is then simply the actual amount of product obtained divided by the theoretical yield times 100.įor the reaction of Al with KOH to form alum the balanced chemical reaction is as follows:Ģ Al (s) + 2 KOH (aq) + 22 H2O (l) + 4 H2SO4 (aq) → 2 KAl(SO4)2 + 12 H2O (s) + 3 H2 (g) From the balanced chemical reaction and the amount of reactants, we determine first the limiting reagent and then theoretical yield of the product. To determine the percent yield of a product in a chemical reaction we need to know the amount of all reactants used, the amount of the product formed and the balanced chemical reaction.

Molar mass of al