Question

Determina cantitatea de solvat care trebuie adaugata la 50 g solutie c= 10% pentru a obtine o solutie de concentratie 20%

Answer 1

cantitatea de solvat = md

ms1 = 50g , c1% = 10%

ms2 = ms1 + md

c2% = (md1+md)x100/(ms1+md)

stim ca c% = mdx100/ms

=> md1 = ms1xc1/100

= 50x10/100 = 5 g

=> md2 = 5+md

=> ms2 = 50+md

=> 20 = (5+md)100/(50+md)

=> md = 6,25 g

facem proba

ms.final = 50+6,25 = 56,25 g

md.final = 5+6,25 = 11,25 g

=> c.final = 11,25x100/56,25

= 20%