Question

1. In 3kg de solutie de acid clorhidric de concentratie 22,5% se adauge 100g acid clorhidric pur. Stabileste concentratia procentuala pentru solutia obtinuta.
2.O masa impura de 20g are puritatea de 60%.Care este masa de substanta pura?
3.Se amesteca o solutie de 800g de concentratie 40% cu apa,rezultand o solutie de concentratie 30%. AFlati cata apa s-a adaugat.

Answer 1

1)md=ms*c/100=3*22,5/100=0,675 kg HCl = 675 g HCl
md final = 675 + 100 = 775 g
ms final = 3000 + 100 = 3100 g
c% final = 775/3100 * 100 = 25 %

2)puritatea=masa pura/masa impura*100
=>masa pura = 60*20/100=12 g masa pura

3)md=ms*c/100=>md=800*40/100=320 g
md final = md initial = 320
ms final = 800+m apa
=>c final = 320/(800+m apa)*100
=>32000=30*(800+m apa)=>32000=24000+30 m apa=>30 m apa = 8000
=> m apa = 266.66 g apa adaugata