Introduction

For many calculations, you will need to be able to find the number of moles of a substance present in a system.

introduction

If you know the mass of the substance present and how much one mole of that substance weighs, you can work out how many moles of the substance you have present. You can use the equation:

Number of Moles =  Mass of Component in Grams 
RMM of Component

Further Details About Equation

The equation simply says that the number of moles is the proportion that the mass of the substance present is of the relative molecular mass.

For example

A substance has an RMM of 40.0 grams. Thus 1 mole weighs 40.0 grams. You have 10.0 grams of the substance.
The proportion that 10.0 grams is of the RMM is 10.0/40.0 which is 0.25. Thus there are 0.25 moles of the substance.

Proportion is:
   Mass of Component in Grams   
RMM of Component
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