Molecular Formula Finder

Molecular Formula Finder

g/mol

Empirical vs. Molecular Formula

It's important to understand the difference between an empirical formula and a molecular formula.

  • The Empirical Formula is the simplest whole-number ratio of elements in a compound. For example, the empirical formula for glucose is CH2O.
  • The Molecular Formula is the actual number of atoms of each element in one molecule of the compound. The molecular formula for glucose is C6H12O6.

The molecular formula is always a whole-number multiple of the empirical formula. This calculator finds that whole-number multiplier (n) to determine the true molecular formula from its simplest ratio.

Frequently Asked Questions

Can the empirical and molecular formulas be the same?

Yes. This happens when the whole-number multiplier 'n' is equal to 1. For example, the empirical formula for water is H2O, and its molecular formula is also H2O. The same is true for compounds like methane (CH4). In these cases, the empirical formula is already the simplest *and* the actual formula.

What information do I need to find the molecular formula?

You always need two pieces of information:
1. The Empirical Formula of the compound (which you can find from mass or percent composition).
2. The Molecular Molar Mass of the compound (which is usually found experimentally using techniques like mass spectrometry).

How does this calculator work?

This tool follows a simple three-step process:
1. Calculate Empirical Formula Mass: It calculates the molar mass of the empirical formula you provide (e.g., CH₂O = 30.03 g/mol).
2. Find Multiplier (n): It divides the Molecular Molar Mass by the Empirical Formula Mass (e.g., 180.16 / 30.03 ≈ 6).
3. Determine Formula: It multiplies all the subscripts in your empirical formula by 'n' to get the final molecular formula (e.g., (CH₂O)₆ = C₆H₁₂O₆).