Thu December 22, 2011 By: Akash Sundi

why do we multiply a coefficient with a simple mole ratio of atoms to obtain empirical formula.please explain step wise with example.

Expert Reply
Fri December 23, 2011

Empirical Formula is the formula that gives the simplest whole-number ratio of atoms in a compound.

The steps followed for finding out the empirical formula are:

Let’s suppose that you have a compound which contains 13.5 g Ca, 10.8 g O, and 0.675 g H.  Now what is the empirical formula of the compound?

Start with the number of grams of each element given.

13.5 g Ca, 10.8 g O, and 0.675 g H

Convert the mass of each element to moles using the molar mass.


Divide each mole value by the smallest number of moles calculated and then round the digits to the nearest whole number.


This is the mole ratio of the elements and is represented by subscripts in the empirical formula.

CaO2H2 or Ca(OH)2

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