An oxide of Nitrogen has the percentage composition : N = 25.94 and O = 74.06. Calculate the empirical formula of the compound.
Solution
1) Step 1 - Converting mass percentage into grams
25.94 % = 25.94 g of N
74.06 % =74.06 g of O
2) Calculating the number of moles


3) Obtaining the simplest molar ratio
Dividing the moles obtained in the previous step by the smallest value from amongst the values obtained for each element, here it is 1.85, we arrive at the simplest molar ratio.

4) Calculating the simplest whole-number ratio
As the simplest molar ratio is not a whole number (in the above example, 2.49 is not a whole number), therefore, it is multiplied by a suitable integer to obtain simple atomic ratio.

5) Writing the Empirical Formula
So, the empirical formula of the compound is N2O5.
Remember that this ratio obtained is the simplest, most reduced ratio. It may or may not be the compounds’ complete molecular formula.
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