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Molecular Weight Formula:
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Molecular weight (MW) is the sum of the atomic weights of all atoms in a molecule. It's expressed in atomic mass units (amu) or grams per mole (g/mol) and is crucial for various chemical calculations.
The calculator uses the molecular weight formula:
Where:
Explanation: The calculator sums the products of each element's atomic mass and its count in the molecule.
Details: Molecular weight is essential for stoichiometric calculations, preparing solutions with specific molarity, determining empirical and molecular formulas, and in various analytical techniques.
Tips: Enter each element followed by its count (e.g., "H2 O1" for water). The count can be omitted if it's 1 (e.g., "H2 O" also works for water). Each element-count pair should be on a separate line or space-separated.
Q1: What's the difference between molecular weight and molar mass?
A: They are numerically identical but molar mass refers to the mass of one mole of substance (g/mol), while molecular weight is dimensionless (though often expressed in g/mol for convenience).
Q2: How accurate are the atomic weights used?
A: The calculator uses standard atomic weights from IUPAC. For most practical purposes, these values are sufficiently accurate.
Q3: Can I calculate molecular weight for ionic compounds?
A: Yes, the same principle applies to ionic compounds, though we typically call it formula weight in such cases.
Q4: What if my element isn't recognized?
A: The calculator includes common elements. For less common elements, you may need to manually calculate using their atomic weights.
Q5: How do I calculate molecular weight of a hydrate?
A: Include the water molecules in your calculation (e.g., for CuSO₄·5H₂O, include all atoms: Cu1 S1 O4 H10 O5).