Chemical formulas were first derived by determining the masses of all the components that combine to create a molecule, leading to the development of two key types of chemistry formulae: molecular formula and empirical formula.
Both of these show the atoms present in a molecule but showcase and focus on different key features.
Key Takeaways
- The empirical formula gives the simplest whole-number ratio of atoms in a compound, whereas the molecular formula gives each element’s actual number of atoms in a molecule.
- An empirical formula can be determined experimentally, while molecular formula is calculated from the empirical formula and the compound’s molecular weight.
- Different compounds can have the same empirical formula but different molecular formulas, whereas the molecular formula of a compound is unique to that compound.
Empirical Formula vs Molecular Formula
Empirical formulas are the simplest whole-number ratios of atoms in a compound, determined through experimental analysis. Molecular formulas give the exact number and types of atoms in a molecule, such as glucose‘s C6H12O6, which can be determined from the empirical formula and molecular weight.
The empirical formula aims to show the atoms of a molecule in their simplest ratio. It can also help predict the type of atoms that are in the ionic compound and the repeating units in a polymer.
It can be used for crystalline ionic compounds, simple molecules, polymers, etc.
On the other hand, the molecular formula gives an exact quantity of atoms in a molecule. It is the formula that consists of the integer quantity of each atom that you calculated or that you are given.
It can be used for covalent compounds but cannot be used for ionic compounds or macromolecules.
Comparison Table
| Parameters of Comparison | Empirical Formula | Molecular Formula |
|---|---|---|
| Definition | It is the simplest form of formula that can be used for a molecule. | It is the formula that shows the type of atoms and the number of each atom present in the molecule. |
| Uses | Used for crystalline ionic compounds, simple molecules, polymers, etc. | Used for covalent compounds but cannot be used for ionic compounds or macromolecules. |
| Molecular Mass | It cannot measure the exact molecular mass. | It can measure the exact molecular mass. |
| Theory | It gives the simplest ratio of a molecule’s atoms. | It gives the exact number of atoms in a molecule. |
| Predictions | It can predict the type of atoms that are in the ionic compound and the repeating unit in a polymer. | It can predict oxidation numbers in an atom, their reactions, and the end products achieved. |
What is Empirical Formula?
Empirical formulas are the simplest type of molecular formulas that may be written. It displays the atom types in the molecule but does not provide the actual number of each atom.
Rather, it offers the molecule’s simplest integer ratio for each atom.
It is the most basic formula for a compound, defined as the ratio of subscripts of the least whole number of components in the formula.
The empirical formula shows the simplest ratio of components in a molecular molecule.
To create the formula for an ionic compound, we can swap the charges of each icon, which immediately provides the number of ions in the molecule.
For macromolecules, we may also create empirical formulations.
When formulating empirical formulas for polymers, we put the repeating unit first, then the letter “n” to indicate that the polymer can have n repeating units.
On the other hand, the empirical formula cannot be used to determine a molecule’s mass, structure, or isomers, but it is helpful for analytical reasons.
For example, Glucose has CH2O as its empirical formula, and the molecule formula for the same is entirely different.
Ionic compounds in their crystalline form are shown with the help of an empirical formula.
For example, we use the empirical formula in a NaCl crystal since we cannot state the exact number of atoms.
What is Molecular Formula?
The kind of atoms and the number of each atom associated with a molecule are represented by molecular formulas. As a result, it determines each atom’s correct stoichiometry.
The atoms are represented by symbols displayed in the periodic table.
Furthermore, the atom numbers should be written as subscripts. Some molecular formulae are neutral (no charge), but if there is one, it can be shown as a superscript on the right side.
The integer quantities of the atoms are included in the subscript when formulating a formula.
It’s a formula created from molecules representing the total number of individual atoms in a compound’s molecule.
The quantity and kind of atoms that make up a molecule are represented in the form of a molecular formula. It is a depiction of the compound’s actual whole number ratio between its constituent parts.
We utilise the molecular formula in chemical processes and when writing any chemical information. We can learn a great deal about a molecule merely by glancing at its molecular formula.
We can also compute the exact molecular mass, for example. Also, if it’s an ionic substance, we can anticipate which ions will be released and how many will be released when it dissolves in water.
Main Differences Between Empirical and Molecular Formula
- An empirical formula shows the simplest version of a formula of a molecule, whereas a molecular formula shows the type and quantity of atoms present in that molecule.
- Empirical formulas can be used for crystalline ionic compounds, simple molecules, polymers, etc. Molecular formulas can be used for covalent compounds.
- An empirical formula cannot measure the exact molecular mass, whereas a molecular formula can.
- The simplest ratio is shown by empirical formulas, and molecular formulas show the exact amount of atoms.
- An empirical formula can predict the type of atoms that are in the ionic compound and the repeating unit in a polymer. A molecular formula can predict oxidation numbers in an atom, their reactions, and the end products achieved.
- https://www.sciencedirect.com/science/article/abs/pii/0584854787800666
- https://www.sciencedirect.com/science/article/abs/pii/0003267086800216
Last Updated : 11 June, 2023
I’ve put so much effort writing this blog post to provide value to you. It’ll be very helpful for me, if you consider sharing it on social media or with your friends/family. SHARING IS ♥️
Piyush Yadav has spent the past 25 years working as a physicist in the local community. He is a physicist passionate about making science more accessible to our readers. He holds a BSc in Natural Sciences and Post Graduate Diploma in Environmental Science. You can read more about him on his bio page.
I wonder if the author was trying to convey that empirical formulas have no use for analytical reasons when it can indeed be helpful for analytical reasons. I read that the empirical formula is used in conjunction with other analytical data to help elucidate the structure of new chemical compounds. I would like to hear the author’s thoughts on this.
Nice article, but honestly, I feel like this information is quite common. I was expecting something more advanced or less known. Good writing, though.
I find it very helpful and interesting to learn about the difference between these two types of chemical formulas. Thank you for the in-depth explanation!
The light tone of the article made it very easy for me to understand those complex concepts. I love the clear comparison table included.
It is very informative. I have learned a lot about chemical formulas that I didn’t know before. Great explanation and examples.
I disagree with the statement that the empirical formula cannot be used to determine a molecule’s mass. From my understanding, it can, to some extent, help determine the composition of a molecule and calculate its molar mass. This is where its usefulness lies.