How do you determine the molar mass of #Fe_2O_3#?

Question

Caleb Adams · Accepted Answer

#color(magenta)("159.7 g/mol")#

#color(green)"We will use the formula below to answer the question:"#

atomic weight of element #xx#number of atoms given by subscript #=# molar mass

First, you want to have a periodic table available so you can determine the atomic weight of Fe and O:

From the chemical formula, we have 2 iron atoms. You have to multiply the atomic mass of Fe by 2 to ascertain an atomic weight of 111.7 g/mol

Next, you have 3 oxygen atoms, so you would multiply the atomic mass of O by 3 to obtain an atomic weight of 48.00 g/mol

Now you want to add the mass of each atom together to obtain the molar mass of the entire compound:

#color(purple) ("111.7 g/mol + 48.00 g/mol = 159.7 g/mol")#

Noah Aldrich · Answer

undefined To determine the molar mass of Fe2O3, you calculate the sum of the atomic masses of the atoms in the compound. For Fe2O3:

Fe: atomic mass = 55.845 g/mol (for one Fe atom)
O: atomic mass = 16.00 g/mol (for one O atom)

Multiply the atomic mass of Fe by 2 (because there are 2 Fe atoms) and the atomic mass of O by 3 (because there are 3 O atoms), then sum the results:

Molar mass of Fe2O3 = (2 * 55.845 g/mol) + (3 * 16.00 g/mol)
                      = 111.69 g/mol + 48.00 g/mol
                      = 159.69 g/mol