Na2CO3
raport atomic=Na:C:O=2:1;3
compozitie procentuala
MNa2CO3=2×ANa+AC+3×AO=2×23+12+3×16=106g
106gNaCO3........46gNa........12gC........48gO
100gNa2CO3........xgNa........ygC...........zgO
x=100×46/106=calculeaza
y=100×12/106=calculeaza
y=100×48/106=calculeaza