Răspuns:
c=mdx100/ms
ro=m/v
daca ro=1g/ml, vs=.1000ml--> ms= 1000g
c1= 18,5% ms1= 1000g---> md1= c1xms1/100= 18,5x1000/100g= 185g cafeina
m,benzoat(solvent)= ms1-md1= 1000-185=>815g
c2= 20% solutia se concentreaza prin:
1-adaugare de cafeina ,md,atat la md1 cat si la ms1
2-utilizarea unei mase de benzoat mai mica
1
c2= (md1+md)100/(ms1+md)
20= (185+md)100/(1000+md)
md-= 18,75g cafeina se adauga in 1000g solutie cu c=c1
Explicație:
