The molar mass of an element is found on the periodic table beneath the element's symbol as the element's atomic mass (Reference: Molar Mass | Definition, Formula & Examples - Lesson - Study.com). This value is typically expressed in atomic mass units (amu), but when referring to molar mass, it's given in grams per mole (g/mol).
Here's a breakdown of how to locate and use this information:
Understanding Atomic Mass and Molar Mass
- Atomic Mass: This is the average mass of an atom of an element, considering the different isotopes and their natural abundance. It's the number you find on the periodic table, usually a decimal.
- Molar Mass: This is the mass of one mole (6.022 x 1023 entities) of a substance. For elements, the molar mass is numerically equal to the atomic mass but expressed in g/mol.
Steps to find the molar mass:
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Locate the Element on the Periodic Table: Find the element you're interested in on the periodic table.
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Identify the Atomic Mass: Look for the number displayed below the element's symbol. This is the atomic mass.
Example: For Carbon (C), the atomic mass listed is approximately 12.01 amu.
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Convert to Molar Mass: Change the units from atomic mass units (amu) to grams per mole (g/mol).
Example: The molar mass of Carbon (C) is approximately 12.01 g/mol.
Example: Finding the Molar Mass of Oxygen
- Find Oxygen (O) on the periodic table.
- The number below the symbol "O" is approximately 16.00.
- Therefore, the molar mass of Oxygen is 16.00 g/mol.
Using Molar Mass in Calculations
Molar mass is crucial for converting between mass (in grams) and moles, a fundamental concept in chemistry. You can use the following formula:
- Moles = Mass (g) / Molar Mass (g/mol)
