What is the Empirical Formula?
Empirical formula is a very fundamental part of our chemistry curriculum and is one of the first things taught to students. It is also one of the concepts that students forget most easily but is still very important for them.
Explaining the Concept with an Example
It is best to illustrate the concept of the empirical formula with an example:
- Take the molecular formula for hexene which is CH2=CHCH2CH2CH2CH3. hexene is what is called a hydrocarbon and it is a molecule composed only of Carbon and Hydrogen atoms with only one double bond between the atoms (making it an alkene).
- The empirical formula of this alkene is given by CH2. (See the following section for the method of how this value was obtained) This is basically the simplest ratio of each atom in the molecule and this is the empirical formula of all alkenes
- Basically for all major groups of molecules they have shared empirical formulae.
- Just keep in mind that you can get the empirical formula for any molecule by simplifying the ratios of each atom in a molecule.
This may be starting to get a little unclear and if you are scratching your head then there are ways to make things easier and find empirical formulae in a short time. The next section will take you through the formulaic approach for calculating the empirical formula so you can appreciate the far easier alternative.
Calculate the Empirical Formula-the Long Way
You may have encountered this type of question while studying chemistry:
Q) A substance has 72g of carbon and 12g of hydrogen. What is its empirical formula?
To answer this you will need to find the number of moles of each atom (72/12 = 6 and 12/1 = 12 for Carbon and Hydrogen, respectively). Then you need to find the ratio between the number of moles so you will divide each value by 6 (the smallest value obtained in the previous step) giving 6/6 and 12/6 giving a ratio of 1:2. Which is the accurate value for alkenes. The calculation for empirical formulas can get much trickier than this when you are not working with convenient whole numbers.
The Method Becomes Much More Complex
This method becomes much more difficult when handling more complex molecules and you definitely do not have time to do all these calculations in your daily life, you would also want to avoid mistakes in your calculations. You may have even forgotten the method you learned from school so it would be best if you seek faster and more accurate methods. What you need is an empirical formula calculator.
A Better Way – the Empirical Formula Calculator
The empirical formula calculator is the tool that will allow you to find the empirical formula of any given molecule very quickly and very accurately. You just need to enter the atomic symbol of the element (C for Carbon, H for hydrogen, O for oxygen etc.) and enter the percentage of mass for each element.
You can click the “Calculate” button and get the empirical formula on your screen at the very next moment. You can now find the empirical formulae for practically all molecules you will deal with in your academic or professional work.
Why use an Empirical Formula Calculator?
Going beyond the ease of use and time-saving nature of the calculator there are many times you may need to use this tool. As a student in college, you will need to calculate empirical formulae for your practicals and as a professional researcher, you have even more reason to make sure that your calculations and results are accurate.
Alternatively, you may be So what would you prefer – writing out the formula, then calculating the formula or simply entering the values and getting the accurate result? The choice is pretty clear.
The empirical formula is an important method to keep in mind for students and academics. But for verifying calculations and in case you have forgotten, the method of the empirical formula calculator can be a very valuable tool.
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