College Chemistry : Empirical and Molecular Formulas
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Example Questions
Example Question #31 : Reactions
What is the correct molecular formula for phosphoric acid?
Phosphoric acid combines a single phosphate ion with three hydrogen ions. The correct molecular formula is 
Example Question #1 : Empirical And Molecular Formulas
A molecule with the empirical formula 
Start by finding the molar mass of of 
Now, divide the molar mass of the molecule by the molar mass of its empirical formula.
In order to find the molecular formula, you will need to multiply the empirical formula by 
Example Question #31 : Reactions
What is the empirical formula for a compound that contains 
We're given the percent composition of the elements carbon and hydrogen in a given compound, and we're asked to determine the empirical formula.
The first thing we have to do is determine the relative molar ratios of each element. In this case, because we are given the percent composition, we can assume that we're starting off with 
Following that, we need to use the molar mass of each element in order to convert it from grams to moles.
In other words, what we have found is that in our compound, for every 
But remember, the empirical formula for any given compound tells us the lowest whole number ratio of the compound's constituent elements. Therefore, we'll need to divide each value by the lowest number out of all the values available.
What this tells us is that for every 
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