Transformam toti molii in grame
mapa=20*18=360g
mCuSO4=0,5*160=80g
mcristalohidrat=m1CuSO4 + m1apa=160 + 90=250g
adunam cantitatile pe componente
mapatot=mapa+m1apa=360+90=450g
mCuSO4tot=mCuSO4 + m1CuSO4=80+160=240g
md=mCuSO4tot=240
ms=mCuSO4tot + mapatot=240+450=690g
c=md*100/ms=240*100/690=34,78%