Empirical Formula Calculator
Find the empirical formula from percent composition of elements.
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Enter the symbol and percent composition for each element (up to 3). The calculator divides each percentage by the atomic mass to get mole ratios, then simplifies to the smallest whole numbers to give the empirical formula.
About the Empirical Formula Calculator
The empirical formula represents the simplest ratio of atoms in a compound. It is determined by converting percent composition to moles, finding the smallest mole ratio, and rounding to whole numbers. This is a standard procedure in analytical chemistry for identifying unknown compounds from combustion analysis or elemental analysis data.
Frequently Asked Questions
What is an empirical formula?
An empirical formula shows the simplest whole-number ratio of atoms of each element in a compound. For example, glucose (C6H12O6) has an empirical formula of CH2O.
How is it different from a molecular formula?
The molecular formula shows the actual number of atoms in one molecule. The empirical formula is the reduced ratio. To find the molecular formula, you need the molar mass of the compound.
What if my percentages do not add up to 100?
That usually means an element is missing. If you measured C, H, and the total is less than 100%, the remainder is often oxygen. Enter it as the third element.