Grams to Moles Calculator
A grams to moles calculator converts the mass of a substance in grams into the amount of substance in moles. This conversion is commonly used in chemistry for stoichiometry, chemical equations, solution preparation, and laboratory calculations.
Grams to Moles Formula
The basic formula is:
moles = mass Γ· molar mass
In symbols:
n = m Γ· M
Here, n is the amount in moles, m is the mass in grams, and M is the molar mass in grams per mole (g/mol).
How to Convert Grams to Moles
First, determine the mass of the substance in grams. Then find its molar mass from the chemical formula and periodic table. Finally, divide the mass by the molar mass.
For example, suppose you have 36 grams of water (H2O).
The molar mass of water is approximately 18.015 g/mol.
Therefore:
n = 36 Γ· 18.015 β 2.00 mol
So, 36 grams of water contains approximately 2 moles.
Finding Molar Mass
Molar mass is the mass of one mole of a substance. For a compound, add the atomic masses of all the atoms shown in its chemical formula.
For example, carbon dioxide is CO2:
12.011 + 2(15.999) β 44.009 g/mol
Therefore, 44.009 grams of CO2 is approximately 1 mole.
Common Grams to Moles Examples
| Substance | Mass | Approx. Molar Mass | Approx. Moles |
|---|---|---|---|
| H2O | 18.015 g | 18.015 g/mol | 1 mol |
| CO2 | 44.009 g | 44.009 g/mol | 1 mol |
| NaCl | 58.44 g | 58.44 g/mol | 1 mol |
| O2 | 32.00 g | 32.00 g/mol | 1 mol |
Why Convert Grams to Moles?
Chemical equations describe quantities in terms of particles and moles rather than simply mass. Converting grams to moles allows you to compare reactants, calculate product amounts, determine limiting reactants, and perform stoichiometric calculations.
Grams to Moles vs. Moles to Grams
These conversions use the same relationship in opposite directions.
Grams to moles: n = m Γ· M
Moles to grams: m = n Γ M
For example, if 2 moles of a substance have a molar mass of 50 g/mol, its mass is:
2 Γ 50 = 100 g
Common Mistakes to Avoid
Make sure the molar mass is calculated from the correct chemical formula. Pay attention to subscripts because they determine how many atoms of each element are present.
Also keep the units consistent: mass should be in grams and molar mass should be in grams per mole.
Quick Summary
To convert grams to moles, divide the mass in grams by the substance's molar mass in grams per mole. The formula is n = m Γ· M. Accurate molar mass is essential for obtaining the correct result.