Question

Se amesteca 300 gr solutie 3 la suta cu 300 gr solutie 9 la suta.Ce concentratie va avea solutia finala

Answer 1

concentratia / 100 = masa dizolvata / masa solutiei 

in prima solutie, masa dizolvata = c x ms / 100 = 3 x 300 / 100 = 9 grame
in a doua solutie, md = 9 x 300 / 100 = 27 grame 

amestecand cele doua solutii, masa solutiei devine 300 g + 300 g = 600 grame
masa dizolvata  = 9 g + 27 g = 36 grame

c /100= md / m sol
c = 36 x 100 / 600 = 6 %