x 4.3g
Cu+2AgNO3=Cu(NO3)2+2Ag
2 mol 2 mol
n(Ag) = m(Ag) / M(Ag) = 4.3g / 108 g/mol = 0.04 mol
x / 2 mol = 0.04 mol / 2 mol
x = (2 mol*0.04 mol) / 2 mol
x = 0.04 mol, n(AgNO3) = 0.04 mol
m(AgNO3) = n(AgNO3)*M(AgNO3) = 0.04 mol * 170 g/mol = 6.8 g
m(AgNO3) = 6.8 g