Question

In ce cantitate de apa trebuie dizolvate 450 g de sare pentru a obtine o solutie cu concentratia de 9/10?

Answer 1

cp=md/ms *100

cp-concentratia procentuala
md-masa de substanta dizolvata
ms-masa solutiei

ms=md +m H2O

9/10= 450/(450+m H2O) *100

9/10 = 45000/ (450 + m H2O)

(450+m H2O)= 10*45000/9

450+ m H2O= 10*5000

450+m H2O=50 000

m H2O= 50 000-450

m H2O= 49 550g

Answer 2

$\frac{9}{10} = \frac{450}{x} =>x= \frac{450*10}{9} =>x= \frac{4500}{9} => x=500 l$