ca sa prepari 5l=5000ml=> 5000g solutie 20%, ai nevoie de md
c=mdx100/ms
20= mdx100/5000---->md=1000g= 1kg sare pura
dar se adauga 1ooog sare de puritate 98% ,deci m,pur este
p= mpurx100/m,impur----->98= m,px100/10000-> m,pur=980g
c= 980x100/5000= 19,6%, unde 5000= 980+m,apa--->m,apa= 4020g
in aceste conditii, saramura obtinuta este mai diluata .