What is a Mole?
In chemistry, a mole is a fundamental unit that measures the amount of substance. One mole corresponds to Avogadro's number (approximately 6.022 × 10^23) of elementary entities (atoms, molecules, ions, etc.). Calculating the number of moles from a given mass is a common task in stoichiometry and laboratory work.
This calculator converts mass (in grams) to amount of substance (in moles) using the molar mass (grams per mole). It is useful for determining how much of a substance you have or need in reactions and for preparing solutions.
Formula
The relationship between mass, molar mass, and moles is:
moles = mass (g) / molar mass (g/mol)Where:
- mass is the mass of the sample in grams (g)
- molar mass is the mass per mole of the substance (g/mol)
- moles is the amount of substance in moles (mol)
Example
Suppose you have 18 grams of water (H2O). The molar mass of water is approximately 18 g/mol. Using the formula:
moles = mass / molar mass = 18 g / 18 g/mol = 1 mol
So, 18 g of water corresponds to 1 mole of water molecules.
How to Use the Calculator
- Enter the mass of the sample in grams.
- Enter the molar mass of the substance in grams per mole (g/mol).
- The calculator will automatically compute the number of moles. Use the chart to visualize the inputs and result.
You can download a PDF summary of the inputs and results for record-keeping or reporting.
Frequently Asked Questions
What if my molar mass is not known?
You can calculate molar mass by summing the atomic masses of all atoms in the molecular formula. Use a periodic table or database to find atomic masses (in g/mol).
Can mass be negative?
No. Mass should be a non-negative value. The calculator validates inputs and will not produce a result if the mass is negative or the molar mass is zero or not provided.
Why are chart bars different units?
The chart displays both input values (grams and grams per mole) and the computed moles. These values have different units; the chart is intended to give a quick visual overview rather than a strict unit-comparable plot.