1.
m.apa = 280 g , md = 60 g
stim ca w% = mdx100/ms
stim ca ms = md+m.apa
= 280+60 = 340 g sol
=> w% = 60x100/340 = 17,6%
2.
principiu , la fel ca la 1.
300 mL apa = 300 g apa
3.
ms1 = 160 g , w1% = 3%
m.apa = 140 g
stim ca w% = mdx100/ms
stim ca ms.final = ms1 + m.apa.adaugata
= 160 + 140 = 300 g sol
md = ms1xw1%/100 = 160x3/100 = 4,8 g
=> w%.final = mdx100/ms.final
= 4,8x100/300 = 1,6%
4.
principiu , la fel ca la 3.
170 mL apa = 170 g apa
5.
ms1 = 60 g , w1% = 1%
=> md1 = ms1xw1%/100
= 60x1/100 = 0,6 g
md.adaugat = 4 g
=> w%.final = md.finalx100/ms.final
md.final = md1 + md.adaugat = 0,6 + 4 = 4,6 g
ms.final = ms1 + md.adaugat = 60 + 4 = 64 g
=> w%.final = 4,6x100/64 = 7,2% (aproximativ)
