Molecular Weight Calculator
Calculate molecular weight and molar mass from chemical formulas using atomic weights
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Calculation Results
Calculation Breakdown
Formula: MW = Σ(atomic weight × count)
Total: 0.000 u
Note: 1 u = 1 Da (Dalton) ≈ 1.66054 × 10⁻²⁷ kg
Quick Common Compounds
Example Calculation
Glucose (C₆H₁₂O₆) Example
Problem: Calculate the molecular weight of glucose
Chemical Formula: C₆H₁₂O₆
Elements: Carbon (C), Hydrogen (H), Oxygen (O)
Step-by-Step Calculation
Step 1: Identify atomic weights: C = 12.01 u, H = 1.008 u, O = 16.00 u
Step 2: Calculate carbon contribution: 6 × 12.01 = 72.06 u
Step 3: Calculate hydrogen contribution: 12 × 1.008 = 12.096 u
Step 4: Calculate oxygen contribution: 6 × 16.00 = 96.00 u
Step 5: Sum all contributions: 72.06 + 12.096 + 96.00 = 180.156 u
Answer: Molecular weight = 180.156 u (Molar mass = 180.156 g/mol)
Common Elements
Units & Definitions
Atomic Mass Unit (u)
Also called Dalton (Da)
1 u ≈ 1.66054 × 10⁻²⁷ kg
Molecular Weight
Mass of one molecule
Expressed in u or Da
Molar Mass
Mass of 1 mole of substance
Expressed in g/mol
Common Compounds
Understanding Molecular Weight
What is Molecular Weight?
Molecular weight (also called molecular mass) is the mass of a single molecule of a substance, expressed in atomic mass units (u) or Daltons (Da). It's calculated by summing the atomic weights of all atoms in the molecule.
Why is it Important?
- •Essential for stoichiometric calculations in chemistry
- •Used to convert between moles and grams
- •Critical for solution preparation and analysis
- •Helps identify unknown compounds in analysis
Molecular Weight vs. Molar Mass
Molecular Weight
Mass of single molecule
Units: u (atomic mass units) or Da (Daltons)
Molar Mass
Mass of 1 mole (6.022 × 10²³ molecules)
Units: g/mol (grams per mole)
Key Point
Numerical values are identical!
Only the units differ: u vs g/mol