1.
a) sa incalzim apa, sa agitam si sarea sa fie pulbere
b)
md = 25g, V.apa = 175 mL, p.apa = 1 g/mL
=> m.apa = V.apaxp.apa = 175x1 = 175 g
=> ms = md + m.apa = 25+175 = 200g
stm ca c% = mdx100/ms = 25x100/200 = 12,5%
c)
ms.final = ms + m.apa.adaugata = 200 + 50 = 250 g
=> c%.final = mdx100/.ms.final = 25x100/250 = 10%
2.
ms = 300g, c% = 60%
din c% => md = msxc%/100
= 300x60/100 = 180g dizolvat
=> m.solvent = ms - md = 300-180 = 120 g
b)
la adugarea unei noi cantitati de dizolvat => solutia se va concentra
md.final = md + m.adaugat = 180+20 = 200g
ms.final = ms + m.adaugat = 300+20 = 320 g
=> c%.final = md.finalx100/ms.final
= 200x100/320 = 62,5%
