Moles, Mass, and Number of Chemical Entities

Interconverting Moles, Mass, and Number of Chemical Entities 

One of the reasons the mole is such a convenient unit for laboratory work is that it allows you to calculate the mass or number of entities of a substance in a sample if you know the amount (number of moles) of the substance. Conversely, if you know the mass or number of entities of a substance, you can calculate the number of moles. 

The molar mass, which expresses the equivalent relationship between 1 mole of a substance and its mass in grams, can be used as a conversion factor. We multiply by the molar mass of an element or compound (,, in g/mol) to convert a given amount (in moles) to mass (in grams)  

we divide by the molar mass (multiply by 1/, ) to convert a given mass (in grams) to amount (in moles)  

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