Formulele de baza pe care trebuie sa le stii: c=md/ms * 100
si ms= md + mapa
c= concentratie; md = masa dizolvat; ms = masa solutie
1. c=(md/(md+mapa)) * 100 = 20 %
2. c= 20%
md = ?
m apa=?
ms = 400g
c/100 = md/ms
md= c*ms/100 = 20*400/100 = 80g
mapa = ms - md = 400 - 80 = 320
3. ms1= 200g
c1= 10%
ms2= 300g
c2= 20%
cf=?
cf= mdf/msf * 100
mdf = md1 + md2 = c1*ms1/100 + c2*ms2/100 = 10*200/100 + 20*300/100
= 20+60 = 80 g
msf= ms1 + ms2 = 200+300 =500 g
cf= mdf/msf * 100 = 80/500*100 = 16%
