Molar Mass Calculator (Molecular Weight)
Welcome to the Molecular Weight (Molar Mass) Calculator, an easy-to-use, web-based tool designed to help you quickly and accurately determine the molecular weight of any chemical compound.
Table of Contents
- How to calculate molar mass?
- Examples of molar mass calculations
- Using the Molecular Weight Calculator
- Molar Masses of Elements Table
- Molar Masses of Simple Molecules Table
- Molar Masses of Acids Table
- Molar Masses of Bases Table
- Molar Masses of Complex Organic Compounds Table
- Frequently Asked Questions
How to calculate molar mass?
Molecular weight, also known as molecular mass or molar mass, is the total mass of all atoms present in a molecule, expressed in atomic mass units (amu) or grams per mole (g/mol). To calculate the molecular weight of a compound, follow these steps:
- Identify the chemical formula of the compound.
- Determine the number of atoms of each element present in the formula.
- Look up the atomic weight of each element on the periodic table.
- Multiply the atomic weight of each element by the number of atoms of that element in the compound.
- Add up the products obtained in the previous step to get the molecular weight of the compound.
Our Molecular Weight Calculator automates this process, allowing you to input the chemical formula and instantly receive the molecular weight of the compound.
Examples of molar mass calculations
Here are two examples to help you understand how molecular weight calculations work:
Example 1: H2O (Water)
For water (H2O), we have two hydrogen (H) atoms and one oxygen (O) atom. The atomic weight of hydrogen is approximately 1.008 amu, and the atomic weight of oxygen is approximately 15.999 amu. To calculate the molecular weight of water:
- Multiply the atomic weight of hydrogen (1.008 amu) by the number of hydrogen atoms (2): 1.008 amu x 2 = 2.016 amu
- Multiply the atomic weight of oxygen (15.999 amu) by the number of oxygen atoms (1): 15.999 amu x 1 = 15.999 amu
- Add the products obtained in steps 1 and 2: 2.016 amu + 15.999 amu = 18.015 amu
Therefore, the molecular weight of water (H2O) is approximately 18.015 amu or 18.015 g/mol.
Example 2: CO2 (Carbon Dioxide)
For carbon dioxide (CO2), we have one carbon (C) atom and two oxygen (O) atoms. The atomic weight of carbon is approximately 12.011 amu, and the atomic weight of oxygen is approximately 15.999 amu. To calculate the molecular weight of carbon dioxide:
- Multiply the atomic weight of carbon (12.011 amu) by the number of carbon atoms (1): 12.011 amu x 1 = 12.011 amu
- Multiply the atomic weight of oxygen (15.999 amu) by the number of oxygen atoms (2): 15.999 amu x 2 = 31.998 amu
- Add the products obtained in steps 1 and 2: 12.011 amu + 31.998 amu = 44.009 amu
Therefore, the molecular weight of carbon dioxide (CO2) is approximately 44.009 amu or 44.009 g/mol.
Using the Molecular Weight Calculator
To use our Molecular Weight Calculator, simply enter the chemical formula of the compound you want to analyze in the designated input field. The calculator will automatically compute the molecular weight based on the atomic weights of the constituent elements and display the result in both amu and g/mol. This tool not only saves time but also minimizes the risk of errors in calculations, making it a valuable resource for anyone working with chemical compounds.
Molar Masses of Elements Table
| Element | Formula | Molar Mass (g/mol) |
|---|---|---|
| Hydrogen | H₂ | 2.016 |
| Oxygen | O₂ | 31.998 |
| Nitrogen | N₂ | 28.014 |
| Chlorine | Cl₂ | 70.9 |
| Fluorine | F₂ | 37.996 |
| Bromine | Br₂ | 159.808 |
| Iodine | I₂ | 253.8 |
| Helium | He | 4.0026 |
| Neon | Ne | 20.18 |
| Argon | Ar | 39.948 |
Molar Masses of Simple Molecules Table
| Simple Molecule | Formula | Molar Mass (g/mol) |
|---|---|---|
| Water | H₂O | 18.015 |
| Carbon Dioxide | CO₂ | 44.01 |
| Methane | CH₄ | 16.043 |
| Ammonia | NH₃ | 17.031 |
| Hydrogen Peroxide | H₂O₂ | 34.014 |
| Carbon Monoxide | CO | 28.01 |
| Ozone | O₃ | 47.997 |
| Nitrous Oxide | N₂O | 44.013 |
| Nitric Oxide | NO | 30.006 |
| Sulfur Dioxide | SO₂ | 64.066 |
Molar Masses of Acids Table
| Acid | Formula | Molar Mass (g/mol) |
|---|---|---|
| Sulfuric Acid | H₂SO₄ | 98.079 |
| Hydrochloric Acid | HCl | 36.461 |
| Nitric Acid | HNO₃ | 63.012 |
| Acetic Acid | CH₃COOH | 60.052 |
| Phosphoric Acid | H₃PO₄ | 97.994 |
| Carbonic Acid | H₂CO₃ | 62.024 |
| Hydrogen Sulfide | H₂S | 34.081 |
| Hydrofluoric Acid | HF | 20.006 |
| Hydrobromic Acid | HBr | 80.912 |
| Hydroiodic Acid | HI | 127.912 |
Molar Masses of Bases Table
| Base | Formula | Molar Mass (g/mol) |
|---|---|---|
| Sodium Hydroxide | NaOH | 39.997 |
| Potassium Hydroxide | KOH | 56.106 |
| Calcium Hydroxide | Ca(OH)₂ | 74.093 |
| Ammonium Hydroxide | NH₄OH | 35.046 |
| Magnesium Hydroxide | Mg(OH)₂ | 58.319 |
| Barium Hydroxide | Ba(OH)₂ | 171.341 |
| Strontium Hydroxide | Sr(OH)₂ | 121.633 |
| Lithium Hydroxide | LiOH | 23.946 |
| Cesium Hydroxide | CsOH | 149.913 |
| Rubidium Hydroxide | RbOH | 102.905 |
Molar Masses of Complex Organic Compounds Table
| Compound | Formula | Molar Mass (g/mol) |
|---|---|---|
| Glucose | C₆H₁₂O₆ | 180.156 |
| Sucrose | C₁₂H₂₂O₁₁ | 342.296 |
| Ethanol | C₂H₅OH | 46.069 |
| Benzene | C₆H₆ | 78.114 |
| Octane | C₈H₁₈ | 114.223 |
| Ethylene | C₂H₄ | 28.054 |
| Propylene | C₃H₆ | 42.081 |
| Formaldehyde | CH₂O | 30.026 |
| Isoprene | C₅H₈ | 68.119 |
| Buckminsterfullerene | C₆₀ | 720.660 |
Frequently Asked Questions
What is molar mass?
Molar mass is the mass of one mole of atoms, molecules, or ions of a substance, expressed in grams per mole (g/mol). It is a fundamental value for performing chemical calculations.
How is the molecular weight of a compound calculated?
To calculate it:
- Identify the chemical formula of the compound.
- Count the atoms of each element.
- Refer to the atomic weights in the periodic table.
- Multiply and add to get the total.
What is the difference between molar mass and molecular weight?
Although the terms are often used interchangeably, molar mass is expressed in g/mol and refers to the mass of one mole of a substance. Molecular weight is expressed in amu (u) and represents the relative mass of a molecule.
Why is it useful to know the molar mass?
Knowing the molar mass allows you to:
- Perform calculations in chemical reactions.
- Prepare chemical solutions accurately.
- Determine stoichiometric ratios.
- Conduct quantitative analyses.