Grams To Moles
Convert grams to moles for any chemical substance using molar mass. Free online calculator with substance selector, breakdown tables, and interactive charts for students, teachers, and lab professionals.
About This Calculator
The Grams To Moles Calculator converts a given mass of any chemical substance into the corresponding number of moles using the fundamental formula n = m / M, where n is the number of moles, m is the mass in grams, and M is the molar mass in grams per mole. It also computes the total number of molecules by multiplying the moles by Avogadro's number (6.022 × 10²³).
This calculator is essential for students studying stoichiometry, chemistry lab technicians preparing solutions, and researchers calculating reagent quantities. It includes a built-in substance selector with common molecules like Water (H₂O), Glucose (C₆H₁₂O₆), Methane (CH₄), Ethanol (C₂H₅OH), Carbon Dioxide (CO₂), Ammonia (NH₃), Sodium Chloride (NaCl), Sulfuric Acid (H₂SO₄), Nitric Acid (HNO₃), and Acetic Acid (CH₃COOH). For any other substance, simply select 'Custom Substance' and enter the molar mass manually.
The mole is the SI base unit for measuring the amount of a substance. One mole contains exactly 6.02214076 × 10²³ elementary entities (Avogadro's number). Converting between grams and moles is one of the most common calculations in chemistry, forming the basis for stoichiometric calculations, limiting reactant analysis, and solution preparation.
About the Formula
The conversion uses the formula: Moles = Mass (g) / Molar Mass (g/mol). The molar mass is calculated by summing the atomic masses of all atoms in the molecular formula. For instance, water (H₂O) has two hydrogen atoms (1.008 g/mol each) and one oxygen atom (15.999 g/mol), giving a molar mass of 18.015 g/mol. Therefore, 100 grams of water contains 100 / 18.015 ≈ 5.551 moles, which is approximately 3.34 × 10²⁴ water molecules.
Results update instantly and can be shared via a unique URL that preserves all input values, making it easy to bookmark specific calculations or share them with colleagues and classmates.
Frequently Asked Questions
How do I convert grams to moles?
To convert grams to moles, divide the mass of the substance in grams by its molar mass (g/mol). The formula is: moles = mass / molar mass. For example, 100 grams of water (molar mass 18.015 g/mol) equals 5.551 moles.
What is molar mass and how is it calculated?
Molar mass is the mass of one mole of a substance, expressed in grams per mole (g/mol). It is calculated by summing the atomic masses of all atoms in a molecule from the periodic table. For example, water (H2O) has a molar mass of 2(1.008) + 15.999 = 18.015 g/mol.
Can I calculate moles from grams for any substance?
Yes, you can calculate moles from grams for any substance as long as you know its molar mass. Our calculator includes a built-in substance selector with common molecules like water, glucose, methane, ethanol, and carbon dioxide, or you can enter a custom molar mass for any other substance.
How do I convert moles back to grams?
To convert moles to grams, multiply the number of moles by the molar mass. The formula is: mass = moles × molar mass. For instance, 2 moles of water (18.015 g/mol) would have a mass of 2 × 18.015 = 36.03 grams.
What is Avogadro's number and how is it used?
Avogadro's number (6.022 × 10²³) is the number of particles (atoms, molecules, or ions) in one mole of a substance. Our calculator multiplies the number of moles by Avogadro's number to show the total number of molecules, helping you understand the scale of chemical quantities at the molecular level.
Is this grams to moles calculator free to use?
Yes, this calculator is completely free to use with no registration or hidden charges. You can bookmark or share your calculation results via the shareable URL link.
How accurate are the molar mass values?
Molar mass values are calculated using standard atomic weights from the periodic table, rounded to 3 decimal places for precision. The calculator uses these values to compute moles to 6 decimal places, making it suitable for laboratory work, homework, and professional chemistry applications.
What is the difference between moles and molecules?
A mole is a unit of amount measuring 6.022 × 10²³ particles, while a molecule is a single particle composed of two or more atoms bonded together. One mole of a substance always contains Avogadro's number of molecules. For example, 1 mole of water contains approximately 6.022 × 10²³ water molecules.