How to Convert Grams to Moles

Steps to Convert Grams to Moles

Grams and moles are two ways to express mass.
Grams and moles are two ways to express mass. Tomasz Sienicki, Creative Commons
By
Anne Marie Helmenstine, Ph.D.
Anne Marie Helmenstine, Ph.D.
Chemistry Expert
  • Ph.D., Biomedical Sciences, University of Tennessee at Knoxville
  • B.A., Physics and Mathematics, Hastings College
Dr. Helmenstine holds a Ph.D. in biomedical sciences and is a science writer, educator, and consultant. She has taught science courses at the high school, college, and graduate levels.
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Updated on February 09, 2019

Many chemical calculations require the number of moles of a material, but how do you measure a mole? One common way is to measure the mass in grams and convert to moles. Converting grams to moles is easy with these few steps.

The Process

  1. Determine the molecular formula of the molecule.
    Use the periodic table to determine the atomic mass of each element in the molecule.
    Multiply each element's atomic mass by the number of atoms of that element in the molecule. This number is represented by the subscript next to the element symbol in the molecular formula.
    Add these values together for each different atom in the molecule. This will give you the molecular mass of the molecule. This is equal to the number of grams in one mole of the substance.
    Divide the number of grams of the substance by the molecular mass.

The answer will be the number of moles of the compound.

See an example of converting grams to moles.

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Helmenstine, Anne Marie, Ph.D. "How to Convert Grams to Moles." ThoughtCo, Aug. 25, 2020, thoughtco.com/how-to-convert-grams-to-moles-608486. Helmenstine, Anne Marie, Ph.D. (2020, August 25). How to Convert Grams to Moles. Retrieved from https://www.thoughtco.com/how-to-convert-grams-to-moles-608486 Helmenstine, Anne Marie, Ph.D. "How to Convert Grams to Moles." ThoughtCo. https://www.thoughtco.com/how-to-convert-grams-to-moles-608486 (accessed June 10, 2023).
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