Question

Rezolvati:
a) Se amesteca 100 g solutie de concentratie 10% cu 400g solutie de concentratie 8% . Calculati concentratia finala a solutiei.
b) Peste 95g solutie de soda caustica de concentratie 5% se mai adauga 5g soda. Calculati concentratia solutiei obtinute.
REZOLVARE COMPLETA.

Answer 1

Folosesti relatia  c%= mdx100/ms,  de unde md= cxms/100
c-conc. procentuala, md- masa de subst.dizolvata, ms-masa de solutie

ms1=100g
c1=10%---> md1=10g

ms2=400g
c2= 8%---> md2=32g

ms3=ms1+ms2= 500g
md3=md1+md2= 42g----------------> c3= 42x100/500=................calculeaza !
trebuie sa-ti dea o valoare cuprinsa intre 10% si 8% !



aflu md 1:     md1= c1xms1/100=5x95/100= >4,75g
in solutia 2: md2=md1+5= 9,75g
                   ms2= ms1+5=100g
calculeaza  c2= md2x100/ms2=.........................................................!!!!!