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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 represents the mass of one mole of a substance and is typically expressed in grams per mole (g/mol).
Molecular weight is calculated using the formula:
Where:
Explanation: For each element in the molecule, multiply its atomic weight by the number of times it appears in the formula, then sum all these products.
Details: Molecular weight is essential in chemistry for stoichiometric calculations, determining molar concentrations, preparing solutions, and understanding physical properties of substances.
Tips: Enter atomic weights and stoichiometric coefficients as comma-separated values. Ensure both lists have the same number of elements and are in the same order.
Q1: What's the difference between molecular weight and molar mass?
A: While often used interchangeably, molecular weight specifically refers to the mass of molecules, while molar mass can refer to any chemical compound.
Q2: How do I find atomic weights?
A: Atomic weights are available on the periodic table. Standard values are published by IUPAC and are typically rounded to two decimal places.
Q3: Does molecular weight affect physical properties?
A: Yes, molecular weight influences boiling point, melting point, density, and other physical properties of substances.
Q4: How accurate is this calculation?
A: The accuracy depends on the precision of the atomic weights used. For most applications, standard atomic weights with two decimal places provide sufficient accuracy.
Q5: Can I calculate molecular weight for ionic compounds?
A: Yes, the same principle applies. For ionic compounds, we typically refer to it as formula weight rather than molecular weight.