Empirical Formula Calculator - Molecular Formula Calculator
Free empirical formula calculator & molecular formula calculator. Calculate empirical formulas from percent composition or mass data with step-by-step solutions. Our calculator uses stoichiometry principles to determine the simplest whole-number ratio of atoms in compounds and convert to molecular formulas.
Last updated: October 28, 2025
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Empirical Formula Result
Empirical Formula:
CH2O
Molar Amounts:
C: 3.3306 mol, H: 6.6468 mol, O: 3.3312 mol
Simplest Ratio:
C: 1.00, H: 2.00, O: 1.00
Calculation Steps:
1. Convert to moles 2. Divide by smallest 3. Round to whole numbers
Interpretation:
Empirical formula CH2O represents the simplest ratio of elements
Key Concepts:
- • Empirical formula = simplest whole-number ratio of atoms
- • Convert mass to moles using atomic mass
- • Divide all mole values by the smallest
- • Multiply to get whole numbers if needed
- • Molecular formula = empirical formula × n
Empirical Formula Calculator Types & Methods
Input types
Mass or Percent
Works with mass in grams or percent composition data
Formula
(Empirical)ₙ
Multiply empirical formula by whole number n using molar mass
Assume
100g total
Percentages convert directly to grams when assuming 100g sample
Process
Moles ÷ smallest
Divide all mole values by smallest to get simplest ratio
Key formula
moles = mass / atomic mass
Convert between mass and moles using atomic masses
Analysis
Complete solution
Full step-by-step analysis of chemical formula calculations
Quick Example Result
For compound with 40.0% C, 6.7% H, 53.3% O:
Empirical Formula
CH₂O
How Our Empirical Formula Calculator Works
Our empirical formula calculator uses stoichiometric principles to determine the simplest whole-number ratio of atoms in a compound. The calculation converts mass or percent composition to moles, then finds the simplest integer ratio by dividing by the smallest value and multiplying to eliminate decimals.
Empirical Formula Calculation Steps
This systematic approach ensures accurate determination of the simplest formula representing the compound's composition. The empirical formula may equal the molecular formula if already in simplest form.
Shows conversion from mass to moles to simplest ratio
Mathematical Foundation
Empirical formula determination relies on the mole concept - the fundamental unit in chemistry that relates mass to number of particles. Since atoms combine in whole-number ratios, we must convert mass (which varies by element) to moles (which count atoms). The atomic mass serves as the conversion factor: 1 mole of an element has a mass in grams equal to its atomic mass.
- Empirical formula shows simplest ratio, molecular formula shows actual atoms
- Mole = 6.022 × 10²³ particles (Avogadro's number)
- Atomic mass units: C = 12.01, H = 1.008, O = 16.00, N = 14.01
- Percent composition assumes 100g sample for easy conversion
- Common multipliers: 0.5 → ×2, 0.33 or 0.67 → ×3, 0.25 or 0.75 → ×4
- Molecular formula = (empirical formula)ₙ where n is whole number
Sources & References
- Chemistry: The Central Science - Brown, LeMay, Bursten (14th Edition)Standard reference for stoichiometry and empirical formulas
- General Chemistry: Principles and Modern Applications - Petrucci, Herring, Madura, BissonnetteComprehensive coverage of chemical formulas and composition
- American Chemical Society - Chemical Education ResourcesEducational materials for chemistry calculations and formulas
Need help with other chemistry tools? Check out our mole calculator and percent yield calculator.
Get Custom Calculator for Your PlatformEmpirical Formula Calculator Examples
Given Data:
- Carbon: 40.0%
- Hydrogen: 6.7%
- Oxygen: 53.3%
- Assume: 100g sample
Calculation Steps:
- Convert % to g: C=40.0g, H=6.7g, O=53.3g
- To moles: C=3.33mol, H=6.65mol, O=3.33mol
- Divide by 3.33: C=1.00, H=2.00, O=1.00
- Write formula: CH₂O
Result: Empirical Formula = CH₂O
This is the simplest whole-number ratio. Molecular formula could be CH₂O, C₂H₄O₂, C₃H₆O₃, etc.
Water Example
11.2% H, 88.8% O
Empirical: H₂O (also molecular)
Glucose Example
40% C, 6.7% H, 53.3% O
Empirical: CH₂O, Molecular: C₆H₁₂O₆
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