Home
Back
Molecular Weight Formula:
Molecular weight (MW) is the sum of the atomic weights of all atoms in a molecule. It's expressed in grams per mole (g/mol) and is crucial for chemical calculations and stoichiometry.
The molecular weight is calculated using the formula:
Where:
Explanation: For each element in the molecule, multiply its atomic weight by the number of atoms present, then sum all these values to get the total molecular weight.
Details: Molecular weight is essential for preparing solutions with specific molar concentrations, determining stoichiometric ratios in reactions, and calculating yields in chemical synthesis.
Tips: Enter the chemical formula using standard notation (e.g., H2O for water, C6H12O6 for glucose). The calculator will parse the formula and sum the atomic weights of all atoms.
Q1: What's the difference between molecular weight and molar mass?
A: They are numerically identical but molecular weight refers to molecules while molar mass can refer to any chemical entity (atoms, ions, etc.).
Q2: How are atomic weights determined?
A: Atomic weights are weighted averages of isotopic masses based on their natural abundance, as determined by IUPAC.
Q3: Does the calculator work for ionic compounds?
A: Yes, the calculator works for any chemical formula, including ionic compounds like NaCl or CaCO3.
Q4: What if my formula contains parentheses?
A: This calculator handles simple formulas without parentheses. For complex formulas, consider using a more advanced calculator.
Q5: Why are atomic weights not whole numbers?
A: Most elements have multiple isotopes with different masses, so the atomic weight is an average that accounts for natural isotopic distribution.