Question

Determinati cantitatea de apa care trebuie evaporata pentru a obtine o solutie cu concentratia 40% din 600 g solutie soda caustrica de concentratie 30%.
HELP!!

Answer 1

ms1 = 600g ,c1% = 30%

c%final = 40%

stim ca c% = mdx100/ms

=> md = constant in acest caz

= msxc1%/100 = 600x30/100 = 180 g

notam cu a = masa de apa evaporata

ms.final = ms1-a

=> c%final = mdx100/ms.final

=> 40 = 180x100/(600-a)

=> a = 6000/40 = 150 g apa evaporata

facem proba:

ms = 600-150 = 450g

md = 180g

=> c% = 180x100/450 = 40%, deci verifica calculele de mai sus