a)
ms = 40 g suc lamaie, c% = 6,5%
stim ca c% = mdx100/ms
=> md = msxc%/100 = 40x6,5/100 = 2,6 g acid citric
m.apa adaugata = 40 g
=> ms.final = ms + m.apa adugata = 40 + 40 = 80 g sol. finala
=> c%.finala = mdx100/ms.finala
=> c%.finala = 2,6x100/80 = 3,25%
b)
ms.finala = 200 g , c%.finala = 1%
stim ca c% = mdx100/ms
=> md = msxc/100 = 200x1/100 = 2 g
ms.finala = md + m.apa
=> m.apa = ms.finala - md = 200 - 2 = 198 g apa adugata pt. prepararea solutiei
