Question

Ce cantitate de alcool trebuie adaugata la 50 g soltie de concentratie 25% pentru a ajunge la o concentratie de 40%

Answer 1

C=md/ms*100=>md=C*ms/100=25*50/100=12,5g alcool

ms=md+mH2O=>mH2O=ms-md=50-12,5=37,5g 

C=md/md+mH2O => 40=md/md+37,5*100 => 60md=1500 => md=25g 

m alcool adaugat = 25-12,5=12,5g