Question

Ce volum de apa cu densitatea 1g/cm^3 se adauga peste 16 g de soda, de concentratie 32% pentru a obtine o noua solutie cu concentratia 25% ?

Answer 1

C=md/ms*100=>md=C*ms/100=32*16/100=5,12g NaOH

ms=md+mH2O=>mH2O=ms-md=16-5,12=10,88

25=5,12/5,12+mH2O*100 => 25(5,12+mH2O=512 => 128+25mH2O=512 => 25mH2O=384 => mH2O=15,36g

m H2O adaugat = 15,36-10,88=4,48g

V H2O=4,48cm3(mL)

1cm3=1mL