Question

Peste 400g solutie NaCl se adauga 200g apa. Concentratia solutiei devine 20%. Concentratia procentuala a solutiei initiale este :

Answer 1

Ms=400g+200g=600g
c%=$\frac{Md}{Ms}*100$
20=$\frac{Md}{600}*100$
12000=Md*100
Md=120g=Md2
c%=$\frac{Md2}{Ms2}*100$
c%=$\frac{120}{400}*100$=30