Question

1)Stiind ca masa apei este de 400 g si concentratia 20% afla masa solutiei si masa subst .dizolvate .

Answer 1

c=md*100/ms
Notam md=x; ms=mapa+md=400+x;
20=100x/400+x=> 8000+20x=100x=> 8000=80x => x=100 g=md
ms=500g;

Answer 2

c%=md/ms * 100 = md/(md+m apa)*100 = 20
=>100 md = 20 md + 20 m apa
(100 - 20)md=20*400=>80 md = 8000=>md = 100 g
ms = md+m apa = 100+400=>ms = 500 g solutie