Amount of Substance Calculator

Understanding Amount of Substance Calculator

The amount of substance (moles) relates mass to the number of particles. One mole contains Avogadro's number (6.022×10²³) of particles.

How to use this calculator

1. Enter the mass of the substance, in grams, into the mass field.
2. Enter the molar mass, in grams per mole, into the molar mass field.
3. Check that both values use matching units, so the calculation is valid.
4. Read the result, which gives the amount of substance in moles.

The formula explained

The formula \(n = \frac{m}{M}\) computes the number of moles by dividing mass by molar mass. It tells you how many moles are contained in a given mass of a substance.

• n = amount of substance, in moles
• m = mass of the sample, in grams
• M = molar mass of the substance, in grams per mole

Step by step method

1. Write down the mass \(m\) and the molar mass \(M\).
2. Substitute the values into \(n = \frac{m}{M}\).
3. Divide the mass by the molar mass to find \(n\).

Worked example

Problem. A sample of sodium chloride has a mass of \(11.7\) g and a molar mass of \(58.44\) g/mol. Find the amount of substance in moles.

1. Use the formula \(n = \frac{m}{M}\).
2. Substitute the values, \(n = \frac{11.7}{58.44}\).
3. Calculate \(n \approx 0.200\) mol.

Tips and common mistakes

• Make sure the mass is in grams and the molar mass is in grams per mole, otherwise the result will be wrong.
• If the calculator gives a decimal, you can round it to the number of significant figures that matches your input data.

Frequently asked questions