How To Calculate Moles
Moles, Mass, and Molar Mass
If you know two of the three values, you are able to calculate the third. The calculation formula is n=m/M
Molar Mass
There are two ways to calculate molar mass. If you know the mass and amount of moles in a substance, you can calculate molar mass by diving the mass by the amount of moles - eg. 88g of mass and 2 moles = 44g mol-1 (molar mass). The second way to calculate molar mass does not use mass and amount of moles, instead adds up the individual molar mass of each atom in a molecule - eg. the molar mass of CO2 is 12 + 16 + 16 = 44g mol-1
Moles
To calculate moles, you divide the mass by the molar mass - eg. 88g of mass and 44g mol-1 of molar mass = 2mol
Mass
To calculate mass, you multiply the molar mass and the amount of moles - eg. 2 mol and 44g mol-1 of molar mass = 88g
Volume and Concentration
The calculation of volume and concentration also includes the usage of amount of moles. The calculation formula is C=n/V
Volume
To calculate volume, you divide the amount of moles by the concentration - eg. 2 moles and 0.5 mol L-1 of concentration = 4L
Concentration
To calculate concentration, you divide the amount of moles by the volume - eg. 2 moles and 4L of solution = 0.5 mol L-1
The amount of moles can also be calculated using this equation, by multiplying the concentration and volume.
The triangle can be used to easily figure out which calculation to use. If you need the variable on top, then multiply the bottom. If you need a variable on the bottom, then divide the top value by the other bottom value.