Question

How do you find the molar mass of hematite?

Answer 1

To calculate the molar mass of hematite, we first need to know what is hematite. Hematite is a compound found in various rocks and soils. It is an iron oxide with the molecular formula $F{{e}_{2}}{{O}_{3}}$.

Complete answer: When a sample contains Avogadro's number ($N=6.022\times {{10}^{23}}$) of particles (like molecules, atoms, electrons, or ions) of a compound or molecule, it is said to be equivalent to one mole of that compound or molecule.
The sum of the mass of Avogadro's number ($N=6.022\times {{10}^{23}}$) of particles of a compound or molecule will be equal to the mass of one mole of that compound or molecule.
The weight of one mole of a sample is known as its molar mass. The weight of one mole of an atom is known as its atomic mass. Its SI unit is g/mol.
Now, to calculate the molar mass of hematite, we need to know the atomic masses of the atoms present in hematite.
The average atomic mass of iron, Fe = 55.847
The average atomic mass of oxygen, O = 14.9994
So, the molar mass of hematite would be the sum of the atomic mass of all the atoms present in the molecule.
Molar mass of hematite = $2\times atomic\text{ mass of Fe}$ + $3\times atomic\text{ mass of O}$.
Molar mass of hematite = $2\times 55.847+3\times 14.994$ g/mol
Molar mass of hematite = 159.6922 g/mol.

Note: It should be noted that we can also calculate the number of particles in any sample from the molar mass of the sample. When a mass of one mole of any chemical compound or molecule is present, the number of particles in it will be equal to Avogadro's number ($N=6.022\times {{10}^{23}}$).