What is the molar mass of iron (III) oxide (#Fe_2O_3#)?

1 Answer
Dec 26, 2016

#159.70 g/(mol)#


#color(purple)"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:

  • Fe has an atomic weight of 55.85 g/mol
  • O has an atomic weight of 16.00 g/mol

From the chemical formula, there are 2 iron atoms, so the atomic mass has to be multiplied by 2, which gives you a value 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 (magenta) ("111.7 g/mol + 48.00 g/mol = 159.70 g/mol")#