Finding the number of moles

the quantity of anything that has the same number of particles found in 12.000 grams of carbon-12.  A mole is a unit of measurement just like a dozen or a ream.  It means 6.02 x 10^23 unit

What is the mass of 3 moles of potassium nitrate [KNO3]? (gram formula mass = 101 g/mol)

mole = 3 moles (we know this because its unit is moles.

gram formula mass (gfm) = 101 g/mol

unknown = mass

Substitute and Solve:

How many moles are in 270. g of dinitrogen pentoxide [N2O5]? (gram formula mass = 108 g/mol)?

gram formula mass = 108

mass = 270

unknown = moles