How to Find Molar Mass in Chemistry

Molar mass is just the mass of one mole of an element or compound. The average molar mass of every element is listed on the periodic table as the bottom number.

How to Find the Molar Mass of an Element


Molar masses of elements are as simple as looking as the bottom number in each box. For example, the molar mass one mole of Oxygen would be 16 grams (or 15.999 if you wanna be exact).

Molar Masses of Compounds

Compounds are similar. When finding the molar masses of compounds, you have to know how many moles of each element there. NaCl has one mole of Na and one mole of Cl. So looking at the periodic table, one mole of Na weighs 22.989 grams and one mole of Cl weighs 35.45 grams. One mole of NaCl weighs 22.989+35.45= 58.439 grams.

Glucose is a little more difficult. One moleculeĀ of Glucose contains 6 carbon atoms, 12 hydrogen atoms, and 6 oxygen atoms. This means you have to find all of the atomic weights of these 3 elements, then multiply them by the amount of atoms in the compound. You should get really close to 180.16 depending on what numbers you use.

More Complicated Compounds

Compounds like Lead(II) nitrate are a little more complicated. Pb(NO3)2 is the formula for lead nitrate. That’s 1 atom of lead, 2 atoms of Nitrogen and 6 atoms of oxygen. This adds up to be 331.21 grams per mole.

That’s all there is to it! Finding molar mass is as easy as that!

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