Converting Between Mass and Moles

How Does One Convert Between Moles and Mass?
To convert between moles and mass, molar mass is utilized as the conversion factor. Although simple it is important to that note that:

• The appropriate units are cancelled 
• The number of significant digits matches that of the least number of the given data  

What's the Process?

Only one mathematical step is needed in these conversions: 

 

Examples 

• How many moles are present in a 2.5 gram sample of Ammonium Phosphate?  
• Ammonium Phosphate = (NH3)PO4 
• (NH3)PO4 = 149 grams  

                         2.5 grams x 1 mole/ 149 grams 

                      = 0.017 moles 

• A sample of Hydrochloric acid contains 0.54 moles. How many grams of Hydrochloric Acid is this?  
• Hydrochloric Acid = HCl 
• HCL = 36.5 grams  

                        0.54 moles x 36.5 grams/ 1 mole 

                      = 20 grams

Below is a video that thoroughly goes over the process of converting moles to grams:

 

And likewise, here is one that explains how to convert from grams to moles: 

  

-Benedict Suratos