Molar Mass Calculator
Calculate molecular weight and molar mass of chemical compounds
Calculate Molar Mass
Enter chemical formula (e.g., H2O, CO2, NaCl)
Molar Mass Results
Element Breakdown
| Element | Count | Atomic Mass | Total Mass | Percentage |
|---|---|---|---|---|
H Hydrogen | 2 | 1.0079 | 2.0159 | 11.19% |
O Oxygen | 1 | 15.9994 | 15.9994 | 88.81% |
| Total Molar Mass | 18.0153 | 100.00% | ||
Unit Conversions
Calculation Steps
Molar Mass Formula
Example: Water (H₂O) Molar Mass
Given Information
Chemical Formula: H₂O
Elements: Hydrogen (H) and Oxygen (O)
Composition: 2 hydrogen atoms, 1 oxygen atom
Step-by-Step Calculation
1. Hydrogen: 2 atoms × 1.00794 g/mol = 2.01588 g/mol
2. Oxygen: 1 atom × 15.9994 g/mol = 15.9994 g/mol
3. Total: 2.01588 + 15.9994 = 18.01528 g/mol
Result: Molar mass of H₂O = 18.0153 g/mol
Common Atomic Masses
Molar Mass vs Molecular Weight
Quick Tips
Use periodic table for atomic masses
Count atoms carefully in formulas
Multiply atomic mass by atom count
Sum all element contributions
Check units (g/mol is standard)
Understanding Molar Mass
What is Molar Mass?
Molar mass is the mass of one mole of a substance, expressed in grams per mole (g/mol). It represents the mass of 6.022 × 10²³ (Avogadro's number) particles of that substance.
Key Concepts:
- • Mole: SI unit for amount of substance
- • Avogadro's Number: 6.022 × 10²³ particles/mol
- • Atomic Mass: Mass of individual atoms
- • Formula Mass: Sum of atomic masses in compound
Calculation Method
Step 1: Identify Elements
Determine all elements in the chemical formula and their quantities.
Step 2: Find Atomic Masses
Look up atomic masses from periodic table (usually in g/mol).
Step 3: Calculate and Sum
Multiply each atomic mass by its count, then sum all contributions.
Applications in Chemistry
Stoichiometry
Calculate reactant and product quantities in chemical reactions using mole ratios.
Solution Preparation
Determine mass needed to prepare solutions of specific molarity or molality.
Gas Laws
Convert between mass and moles in ideal gas law calculations (PV = nRT).
Important Relationships
Fundamental Equations
Molar Mass: M = m/n
Where: M = molar mass, m = mass, n = moles
Number of Moles: n = m/M
Mass: m = n × M
Percent Composition
Formula: % = (mass of element/total mass) × 100
Use: Determine composition of compounds
Application: Empirical formula determination
Validation: All percentages sum to 100%