posted by Jerry .
A current of 2.50 A is passed through a solution containing Cu+2 ions for 4.00 hours. Calculate the mass of Cu atoms that form at the cathode.
Convert the charge in coulombs to number of electrons.
Since it takes two electrons per Cu+2 atom, divide the number of electrons by two, and you have the number of atoms of Cu. Change this to mass, either by mass/atom, or change to moles (avag number), then to mass.