Avogadro’s and the Mole Moles • a mole is the number of carbon atoms in exactly 12g of carbon. • a mole is a unit of measurement, just like grams… Grams Moles • the use of molar mass allows the calculation of the mass of a given number of moles (or vice versa) Example • What is the mass of 3.25mol of CO2? Example 2 • How many moles of N2 are there in 50.0g of N2? #mol = g/mol • remember the units of molar mass are g/mol and can be calculated using a given mass divided by a given number of moles Example • If 0.140mol of acetylene gas has a mass of 3.64g, what is the molar mass of acetylene? g/mol = Molecules Moles • Avogadro learned that there 23 are 6.02x10 molecules in every mole! We can use that now to convert molecules first to moles and then change it up! Example • How many moles are there in 6.489 x 1025 molecules of copper(II)sulfate? Example 2 • How many molecules are contained in 45.8 grams of NaOH?