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Question: A compound is found to be \(12.7\% \) carbon, \(3.2\% \) hydrogen, and \(84.1\% \) bromine. What is ...

A compound is found to be 12.7%12.7\% carbon, 3.2%3.2\% hydrogen, and 84.1%84.1\% bromine. What is its empirical formula?

Explanation

Solution

The empirical formula for a compound is defined as the ratio of subscripts of the fewest possible entire number of elements included in the formula. It is also referred to as the most basic formula. The formula of a substance expressed with the smallest integer subscript is called an empirical formula.
Solution
Formula used:
Number of moles = dfracMassMolar massNumber{\text{ of moles = }}dfrac{{Mass}}{{Molar{\text{ mass}}}}

Complete answer:
Assuming that the mass of unknown compound is 100g100g , we can say that it contains 12.7g12.7gof carbon , 3.2g3.2g of hydrogen ,84.1g84.1g of bromine.
We first need to calculate the moles of each element,
Moles of carbon=dfrac12.7g12gmol−1=1.06molMoles{\text{ }}of{\text{ }}carbon = dfrac{{12.7g}}{{12gmo{l^{ - 1}}}} = 1.06mol
Moles of hydrogen=dfrac3.2g1gmol−1=3.2molMoles{\text{ }}of{\text{ }}hydrogen = dfrac{{3.2g}}{{1gmo{l^{ - 1}}}} = 3.2mol
Moles of bromine=dfrac84.1g79.90gmol−1=1.05molMoles{\text{ }}of{\text{ }}bromine = dfrac{{84.1g}}{{79.90gmo{l^{ - 1}}}} = 1.05mol
Dividing each number of moles by the smallest value of number of moles that is of bromine,
Using the formula,
Number of moles = dfracMassMolar massNumber{\text{ of moles = }}dfrac{{Mass}}{{Molar{\text{ mass}}}}
We get,
Mole ratio of carbon = dfrac1.061.05=1.009Mole{\text{ ratio of carbon = }}dfrac{{1.06}}{{1.05}} = 1.009
Mole ratio of hydrogen = dfrac3.21.05=3.047Mole{\text{ ratio of hydrogen = }}dfrac{{3.2}}{{1.05}} = 3.047
Mole ratio of bromine = dfrac1.051.05=1Mole{\text{ ratio of bromine = }}dfrac{{1.05}}{{1.05}} = 1
From the above values, we can conclude that the empirical formula is CH3BrC{H_3}Br .
Hence, the empirical formula is CH3BrC{H_3}Br .

Additional Information:
The molecular formula is a formula generated from molecules that represents the total number of individual atoms in a compound's molecule. A subscript in a molecular formula indicates the number of each type of atom in a molecule of the substance.

Note:
In most circumstances, the empirical rule is used to help determine outcomes when all of the data is not accessible. It lets statisticians or those who are studying the data – to see where the data will fall once everything is available. The empirical rule can also be used to determine whether a set of data is normal.