CuSO4 sulfat de cupru
CuSO4
raport atomic =Cu:S:O=1:1:4
raport de masa=Cu:S:O=64:32:64=2:1:2
compozitie procentuala
MCuSO4=ACu+AS+4×AO=64+32+4×16=160g
160gCuSO4.........64gCu.....32gS.........64gO
100gCuSO4.........xgCu.........ygS..........zgO
x=100×64\160=calculeaza
y=100×32\160=calculeaza
z=100×64\160=calculeaza