1. Cu + 2AgNO3 ==> 2Ag + Cu(NO3)2 ... balanced equation. This is both a single replacement reaction and an oxidation reduction reaction.
Moles of Cu present = 19.0 g Cu x 1 mole Cu/63.55 g = 0.2990 moles Cu
Moles AgNO3 = 125 g AgNO3 x 1 mole AgNO3/169.9 g = 0.7357 moles AgNO3
Which reactant is limiting? It will be Cu because the mole ratio is 2 AgNO3 to 1 Cu and there is more than enough AgNO3. Thus, amount of Ag formed will depend on moles of Cu (0.2990)
Moles of Ag formed = 0.2990 moles Cu x 2 moles Ag/mole Cu = 0.598 moles Ag
Mass (grams) of Ag formed = 0.598 moles Ag x 107.9 g/mole = 64.52 g = 64.5 g of Ag (3 sig. figs.)