To calculate the molar mass of a formula (also known as
relative formula mass, or M
r), simply add together the A
r (
relative atomic mass) of all the elements in that formula.
One mole of atoms or molecules of any substance will have a mass in grams equal to the relative formula mass of that substance.
So, the molar mass of MgCl2 is -
Ar of Mg = 24
Ar of Cl = 35.5. * 2 because there are two Cl.
24 + (35.5 * 2 ) = 95. So the molar mass of MgCl2 is simply 95.