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Empirical Formula Calculator

Enter the atomic symbol and percentage masses of each element, and Calculate the empirical formula.


Percentage of Mass:

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Empirical Formula Calculator:

This empirical formula calculator is used to determine the whole number ratio of atoms in a compound based on the elemental composition (percentage by mass). It shows the complete solution of creating empirical formulas by considering these parameters: element symbol, mass, mole, and mole ratio. 

What is an Empirical Formula?

“A formula that shows the ratio of elements in a compound without detailing the exact number of atomic arrangements”

An empirical formula finds the relative ratio of various atoms of compounds. E.g:

Element Mass Percentage Molar Mass (g/mol) Moles  Mole Ratio
Empirical Formula
C 40 12.01 3.33 1 C
H 6.67 1.01 6.6 2 H2
O 53.33 16 3.33 1 O

Thus, the empirical formula for this compound is CH2O which is named “Formaldehyde”.

Steps to Calculate Empirical Formula:

Step 1: Calculate the percentage composition or mass of an element present in a compound. 

Step 2: Change the mass into moles by dividing them by the atomic mass of that element. 

Step 3: Find the smallest number of moles of the element 

Step 4: Divide the number of moles by the smallest value of moles obtained in step # 3

Step 5: If there is a need to round off the value then obtain the nearest whole number and write in the form of an empirical formula.

Solved Exaxmple:

Suppose a compound that is known to be composed of 52.1% carbon (C), 13.6% hydrogen (H), and 34.3% oxygen (O) by mass. So by using the percentage masses find the empirical formula of that compound. 


Step # 1 - Find Percentage of Mass

The mass percentage of given elements are:

  • C = 52.1%
  • H = 13.6%
  • O = 34.3%

Step # 2 - Convert Mass to Moles

Calculate the moles that are calculated by dividing the percentage mass by the atomic mass. 

➥  Moles of Carbon = 52.1/12.011 

= 4.34 mol

➥  Moles of Hydrogen = 13.6/1.008

= 13.50 mol

➥  Moles of Oxygen = 34.3/15.999

= 2.15 mol

Step # 3 - Find the Smallest Mole Value

From the above step, the smallest mole value is 2.15 mol. 

Step # 4 - Calculate Mole Ratio

The mole ratio is determined by dividing the number of moles of each element by the smallest mole value:

➥  Mole ratio of Carbon = 4.34/2.15

= 2.02 (By rounding off this will be 2)

➥  Mole ratio of Hydrogen = 13.50/2.15

= 6.28 (by rounding off this will be 6)

➥  Mole ratio of Oxygen = 2.15/2.15

= 1 

Step # 5 - Round off and Write the Empirical Formula

Based on the rounded mole ratios, the empirical formula for the compound is C2H6OThe empirical formula calculator automates rounding off the values to know the whole number ratio of atoms for the compound.  


What is the significance of the empirical formula?

The empirical formula is considered vital because it provides information about the number of atoms present in a compound. This property leads to identifying and characterizing various substances with similar functionalities. 

What is the empirical formula of ethanol?


Can a compound have multiple empirical formulas?

No, compounds do not have multiple empirical formulas. You can confirm it with the calculator that finds an empirical formula for a compound given its elemental composition.

What is the empirical formula of Acetaldehyde?


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