How to Calculate Molar Mass of Anything. Step by Step Explanation with Multiple Examples
Molar Mass Of Elements In Periodic Table
What is molar mass?
Lets start by talking what the term means. Simply said, molar mass is how much one mole of a substance weighs. That substance can be an element or a compound.
Mass spectrometry of elements. Worked example: Calculating molar mass and number of moles. Practice: Moles and molar mass. This is the currently selected item. Because each element has a different atomic mass, however, a mole of each element has a different mass, even though it contains the same number of atoms (6.022 × 10 23). This is analogous to the fact that a dozen extra large eggs weighs more than a dozen small eggs, or that the total weight of 50 adult humans is greater than the total weight. Calculating Molar Mass. Molar mass is the mass of a given substance divided by the amount of that substance, measured in g/mol. For example, the atomic mass of titanium is 47.88 amu or 47.88 g/mol. In 47.88 grams of titanium, there is one mole, or 6.022 x 10 23 titanium atoms. The characteristic molar mass of an element is simply the atomic.
How to calculate molar mass with examples
We’ll go through three examples progressing from easy to “difficult”. By the end of this post, you’ll be able to calculate the molar mass of anything.
Example #1: Single element
Sodium (Na)
Finding the molar mass of a single element is really simple. All you need to do is find the atomic mass of the element on the periodic table and report the number with the unit grams per mole or g/mol.
From this, you can see that sodium’s molar mass will be 22.99 g/mol.
Example #2: Simple compound
CH3OH
Start by determining how many of each elements there are by looking the subscripts (small number next to the element symbol). In this compound, there are 1 C, 4 H (3+1), and 1 O. Next, multiply the number of a particular element by its molar mass. Finally, add the products together and you’ll arrive at the answer.
Example #3: “Complicated” compound
(NH4)2CO3
The process is very similar to calculating the molar mass of a simple compound. The only difference is you’ll need to multiply the subscript on the outside of the parenthesis by the subscripts inside the parenthesis.
Start by determining how many of each elements there are. In this compound, there 2N, 8H, 1C, and 3O. Next, multiply the number of a particular element by its molar mass. Finally, add the products together and you’ll arrive at the answer.
After reading and working through these three examples, you should be able to calculate the molar mass of anything.
Additional Resources
This molar mass calculator allows you to double check if you’re getting the right answer.
Version History and References | Disclaimer
Developers and Contributors:
J. S. Coursey, D. J. Schwab, J. J. Tsai, and R. A. Dragoset
NIST Physical Measurement Laboratory
The atomic weights are available for elements 1 through 118 and isotopic compositions or abundances are given when appropriate. The atomic weights data were published by J. Meija et al in Atomic Weights of the Elements 2013, and the isotopic compositions data were published by M. Berglund and M.E. Wieser in Isotopic Compositions of the Elements 2009. The relative atomic masses of the isotopes data were published by M. Wang, G. Audi, A.H. Wapstra, F.G. Kondev, M. MacCormick, X. Xu1, and B. Pfeiffer in The AME2012 Atomic Mass Evaluation.
These data have been compiled from the above sources for the user's convenience and does not represent a critical evaluation by the NIST Physical Measurement Laboratory.
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Related Links
Molar Mass Of Each Element
Development of this database was funded in part by NIST's Systems Integration for Manufacturing Applications (SIMA) Program.
Online: September 1999 | Last update: January 2015