Question

Pentru a dilua 80g de solutie cu concentratia(c%) de 50% pana la o concentratie de 20% , de cata apa avem nevoie?

Answer 1

Stim ca ms1=80g solutie
c1=50%
x=?/c2=20%
c1/100=md1/ms1 => md1=c1*ms1/100=50*80/100=40g substanta
atunci cand adaugam apa, masa solutiei se mareste, masa de substanta ramane la fel
md1=md2
ms2=ms1+x
c2/100=md2/ms2=40/(80+x)
20/100=40/(80+x) => 80+x=40*100/20=200
x=120g apa