Empirical Formula Calculator

Empirical Formula is evaluated from% or Mass - Element 1, Atomic Mass - Element 1 and% or Mass - Element 2. The calculation reports Moles Element 1, Moles Element 2 and Moles Element 3.

Results

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About the Empirical Formula Calculator

Empirical Formula is treated here as a quantitative relation between% or Mass - Element 1, Atomic Mass - Element 1,% or Mass - Element 2 and Atomic Mass - Element 2 and Moles Element 1, Moles Element 2, Moles Element 3 and Ratio Element 1.

The calculator uses a multi formula configuration. Each reported value is read as a direct evaluation of the stored rules with the declared field formats and units.

Formula basis:
Step 1: mol_i =%_i / atomic_mass_i (assume 100g sample)
Step 2: ratio_i = mol_i / min(all mol values)
Step 5: n = actual molar mass / empirical formula mass
Molecular formula = empirical x n

Interpret the outputs in the order shown by the result fields. Optional inputs affect only the outputs that depend on those variables.

Formula & How It Works

The calculation applies the following relations exactly as recorded in the metadata:

Step 1: mol_i =%_i / atomic_mass_i (assume 100g sample)
Step 2: ratio_i = mol_i / min(all mol values)
Step 5: n = actual molar mass / empirical formula mass
Molecular formula = empirical x n

Each output field is produced by substituting the supplied inputs into the relevant relation and then applying the declared rounding or text format.

Worked Examples

Example 1: Glucose Empirical Formula — C₆H₁₂O₆ → CH₂O

Inputs

elem1_pct: 40 elem1_amass: 12.011 elem2_pct: 6.71 elem2_amass: 1.008 elem3_pct: 53.29 elem3_amass: 15.999 molar_mass_actual: 180.16
Moles Element 1: 3.3303 mol. Moles Element 2: 6.6567 mol. Moles Element 3: 3.3308 mol. Ratio Element 1: 1. Ratio Element 2: 2. Ratio Element 3: 1. Empirical Formula Mass: 30.026 g/mol. Multiplier n: 6

With% or Mass - Element 1 = 40, Atomic Mass - Element 1 = 12.011,% or Mass - Element 2 = 6.71 and Atomic Mass - Element 2 = 1.008 as the stated inputs, the result is Moles Element 1 = 3.3303 mol, Moles Element 2 = 6.6567 mol and Moles Element 3 = 3.3308 mol. Each value corresponds to the declared output fields.

Example 2: Aspirin Empirical Formula — C₉H₈O₄

Inputs

elem1_pct: 60 elem1_amass: 12.011 elem2_pct: 4.44 elem2_amass: 1.008 elem3_pct: 35.56 elem3_amass: 15.999 molar_mass_actual: 180.16
Moles Element 1: 4.9954 mol. Moles Element 2: 4.4048 mol. Moles Element 3: 2.2226 mol. Ratio Element 1: 2.25. Ratio Element 2: 1.98. Ratio Element 3: 1. Empirical Formula Mass: 42.037 g/mol. Multiplier n: 4

With% or Mass - Element 1 = 60, Atomic Mass - Element 1 = 12.011,% or Mass - Element 2 = 4.44 and Atomic Mass - Element 2 = 1.008 as the stated inputs, the result is Moles Element 1 = 4.9954 mol, Moles Element 2 = 4.4048 mol and Moles Element 3 = 2.2226 mol. Each value corresponds to the declared output fields.

Example 3: Iron Oxide Empirical Formula

Inputs

elem1_pct: 69.94 elem1_amass: 55.845 elem2_pct: 30.06 elem2_amass: 15.999
Moles Element 1: 1.2524 mol. Moles Element 2: 1.8789 mol. Ratio Element 1: 1. Ratio Element 2: 1.5. Empirical Formula Mass: 87.843 g/mol

With% or Mass - Element 1 = 69.94, Atomic Mass - Element 1 = 55.845,% or Mass - Element 2 = 30.06 and Atomic Mass - Element 2 = 15.999 as the stated inputs, the result is Moles Element 1 = 1.2524 mol, Moles Element 2 = 1.8789 mol and Ratio Element 1 = 1. Each value corresponds to the declared output fields.

Example 4: Unknown Organic Compound

Inputs

elem1_pct: 52.14 elem1_amass: 12.011 elem2_pct: 13.13 elem2_amass: 1.008 elem3_pct: 34.73 elem3_amass: 15.999 molar_mass_actual: 46.07
Moles Element 1: 4.341 mol. Moles Element 2: 13.0258 mol. Moles Element 3: 2.1708 mol. Ratio Element 1: 2. Ratio Element 2: 6. Ratio Element 3: 1. Empirical Formula Mass: 46.069 g/mol. Multiplier n: 1

With% or Mass - Element 1 = 52.14, Atomic Mass - Element 1 = 12.011,% or Mass - Element 2 = 13.13 and Atomic Mass - Element 2 = 1.008 as the stated inputs, the result is Moles Element 1 = 4.341 mol, Moles Element 2 = 13.0258 mol and Moles Element 3 = 2.1708 mol. Each value corresponds to the declared output fields.

Common Use Cases

  • Find empirical formula from elemental percent composition
  • Determine simplest formula from mass data
  • Calculate molecular formula given molar mass and empirical formula