Molecular Weight Calculator
Our Molecular Weight Calculator makes it easy to determine the molecular weight of any chemical formula in just a few seconds. Simply enter a formula (e.g., H₂O, C₆H₁₂O₆) and get a detailed breakdown of each element’s contribution to the total molecular weight.
Let’s explore how molecular weight is calculated and why it’s important.
What is Molecular Weight?
Molecular weight (also called molar mass) is the sum of the atomic weights of all atoms in a given chemical compound. It is expressed in grams per mole (g/mol).
For example, the molecular weight of H₂O (water) is calculated as:
- Hydrogen (H) = 1.008 g/mol × 2 = 2.016 g/mol
- Oxygen (O) = 15.999 g/mol × 1 = 15.999 g/mol
- Total Molecular Weight = 18.015 g/mol
How Does the Molecular Weight Calculator Work?
Our calculator follows these steps to determine molecular weight:
Step 1: Input the Chemical Formula
- You enter a formula like C₆H₁₂O₆ (glucose) into the calculator.
Step 2: Parsing the Formula
- The calculator scans the formula to identify chemical elements and their subscript numbers (if any).
- Example: C₆H₁₂O₆ consists of 6 Carbon (C), 12 Hydrogen (H), and 6 Oxygen (O).
Step 3: Retrieve Atomic Weights
- The calculator looks up atomic weights from the Periodic Table:
- Carbon (C) = 12.011 g/mol
- Hydrogen (H) = 1.008 g/mol
- Oxygen (O) = 15.999 g/mol
Step 4: Multiply & Sum Up
- Multiply the atomic weight of each element by its subscript value:
- Carbon: 6 × 12.011 = 72.066 g/mol
- Hydrogen: 12 × 1.008 = 12.096 g/mol
- Oxygen: 6 × 15.999 = 95.994 g/mol
- Final Molecular Weight = 72.066 + 12.096 + 95.994 = 180.156 g/mol
The result is displayed instantly, along with a step-by-step breakdown of each element’s contribution.
Common Molecular Weight Examples
| Compound | Formula | Molecular Weight (g/mol) |
|---|---|---|
| Water | H₂O | 18.015 |
| Glucose | C₆H₁₂O₆ | 180.156 |
| Carbon Dioxide | CO₂ | 44.009 |
| Ammonia | NH₃ | 17.031 |
| Sulfuric Acid | H₂SO₄ | 98.079 |
Why is Molecular Weight Important?
Molecular weight is essential in chemistry for several reasons:
- Stoichiometry – Determines reactant/product ratios in chemical reactions.
- Concentration Calculations – Helps in preparing solutions (e.g., molarity).
- Pharmaceutical Industry – Drug dosages are based on molecular mass.
- Material Science – Used in polymer and nanotechnology research.