What is the mass in grams of 3.50 mol of the element copper, Cu?

The mass in grams of 3.50 mol of the cu element is calculated as follows

mass = moles x molar mass of Cu (63.5 g/mol)

= 3.50 moles x 63.5 g/mol) = 222.25 grams

moles and moles cancel out each other