Molar Mass Calculator

Molar Mass Calculator

Calculate molar mass and composition of chemical compounds

Enter a chemical formula using element symbols and numbers. Supports parentheses for groups (e.g., Ca(OH)2)

Molar Mass Calculator: Complete Chemistry Guide

Molar mass is the mass of one mole of a substance, expressed in grams per mole (g/mol).It's a fundamental concept in chemistry used for stoichiometric calculations, determining molecular formulas, and converting between mass and moles in chemical reactions.

Our professional molar mass calculator provides molecular analysis including total molecular weight, elemental composition, percentage breakdown, and empirical formula determination for any chemical compound.

Quick Answer

To calculate molar mass: Add the atomic masses of all atoms in the molecular formula. For example, water (H₂O) = 2(1.008) + 1(16.00) = 18.016 g/mol. Include the count of each element and multiply by their atomic masses from the periodic table.

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Mathematical Foundation

M = Σ(ni × Ai)

Where M is molar mass, ni is the number of atoms of element i, and Ai is the atomic mass of element i

Key Chemistry Concepts:

Atomic Mass Units (amu)

Standard unit for atomic and molecular masses, where 1 amu = 1.66054 × 10⁻²⁷ kg. Atomic masses are averaged values accounting for isotope abundance.

Avogadro's Number

6.022 × 10²³ particles per mole. Links the atomic scale to the macroscopic scale, allowing conversion between individual molecules and measurable quantities.

Stoichiometry

Quantitative relationships in chemical reactions. Molar mass enables conversion between grams and moles for balanced equation calculations.

Chemical Formula Guidelines

Basic Notation

Element Symbols

Use standard periodic table symbols: H, C, N, O, Na, Cl, etc.

Subscripts

Numbers after elements indicate quantity: H₂O, CH₄, Ca(OH)₂

Parentheses

Group elements with multipliers: Ca(OH)₂, Al₂(SO₄)₃

Common Examples

Simple Compounds

H₂O (water), CO₂ (carbon dioxide), NaCl (salt)

Complex Compounds

C₆H₁₂O₆ (glucose), CaCO₃ (calcium carbonate)

Ionic Compounds

Ca(OH)₂ (calcium hydroxide), Al₂(SO₄)₃ (aluminum sulfate)

Example Calculations

Example 1: Water (H₂O)

Calculate the molar mass of water molecule

H: 2 atoms × 1.008 g/mol = 2.016 g/mol
O: 1 atom × 16.00 g/mol = 16.00 g/mol
Total molar mass = 2.016 + 16.00 = 18.016 g/mol

Answer: Molar mass of H₂O = 18.016 g/mol

Example 2: Glucose (C₆H₁₂O₆)

Calculate the molar mass of glucose (blood sugar)

C: 6 atoms × 12.01 g/mol = 72.06 g/mol
H: 12 atoms × 1.008 g/mol = 12.096 g/mol
O: 6 atoms × 16.00 g/mol = 96.00 g/mol
Total = 72.06 + 12.096 + 96.00 = 180.156 g/mol

Answer: Molar mass of C₆H₁₂O₆ = 180.156 g/mol

Example 3: Calcium Hydroxide Ca(OH)₂

Calculate molar mass with parentheses notation

Ca: 1 atom × 40.08 g/mol = 40.08 g/mol
O: 2 atoms × 16.00 g/mol = 32.00 g/mol
H: 2 atoms × 1.008 g/mol = 2.016 g/mol
Total = 40.08 + 32.00 + 2.016 = 74.096 g/mol

Answer: Molar mass of Ca(OH)₂ = 74.096 g/mol

Applications in Chemistry

Laboratory Calculations

Solution Preparation

Calculate mass needed for specific molar concentrations

Yield Calculations

Determine theoretical and percent yield in reactions

Research Applications

Drug Development

Molecular weight determination for pharmaceutical compounds

Material Science

Polymer and composite material characterization

Frequently Asked Questions

What's the difference between molecular weight and molar mass?

Molecular weight is the mass of one molecule in atomic mass units (amu).Molar mass is the mass of one mole of substance in grams per mole (g/mol). Numerically they're the same, but the units differ reflecting different scales.

How do I handle hydrated compounds?

Include water molecules in the formula. For example, copper sulfate pentahydrate is CuSO₄·5H₂O. Calculate the molar mass by adding the compound mass plus five times the molar mass of water.

What about isotopes and their effect on molar mass?

Standard atomic masses account for natural isotope abundance. For most calculations, use the standard values. For precise work with specific isotopes, use the exact isotopic masses instead of average atomic masses.

How precise should my molar mass calculations be?

For most academic work, 3-4 decimal places are sufficient. In research, precision depends on your measurement accuracy. Don't report more decimal places than justified by your least precise atomic mass values.

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