(O Level Chem) How to find molar masses?

We have learned from our primary science education that matter is anything that has mass and occupies space. In upper secondary, you are exposed to the more complicated concept of the mole (not the animal nor the mark on your skin). Mole and mass have the same meaning in that they refer to the amount of substance. But to convert between mass and mole is not as straight forward as converting between g and kg. You need to refer to the Periodic Table for values called the relative atomic masses. The word "relative" implies it is a comparison. Relative atomic mass has no unit because it is a comparison between two quantities of the same unit, that is g. Many times, you'll use relative atomic masses to calculate relative molecular masses of molecular compounds or relative formula masses of ionic compounds. Relative molecular masses and relative formula masses have no unit too. But if you express these relative masses in g, you have found the mass of 1 mole of the element or compound. This is called the molar mass. The unit of molar mass is g/mol.

Write down the molecular formula and use the relative atomic masses to find molar mass... 

Example: Find the mass of 1 mole of ethanol.
[Solution]
Relative molecular mass of ethanol C2H5OH
= 2(12) + 16 + 6(1)
= 46

Mass of 1 mole of ethanol = 46 g 

Example: Find the molar mass of ammonium phosphate.
[Solution]
Relative formula mass of ammonium phosphate (NH4)3PO4 
= 3[14 + 4(1)] + 31 + 4(16)
= 149

Molar mass of ammonium phosphate = 149 g/mol  

Note: You must show your working in calculation questions.

The unit of molar mass is g/mol...