S.II:
1.
md = 65g, m.apa = 135g
stim ca ms = md+m.apa = 65+135 = 200g
stim ca c% = mdx100/ms
= 65x100/200 = 32,5%
2.
ms = 500g, c% = 50%
=> md = msxc%/100
= 500x50/100 = 250 g substanta dizolvata
3.
ms1 = 200g, c1% = 25% si c2% = 2c1% = 50%
ms2 = ms1 - m.apa.evaporata = ms1 - a
md = ms1xc1/100 = 200x25/100 = 50g
c2% = mdx100/ms2
=> 50 = 50x100/(200-a)
=> a = 5000/50 = 100 g apa evaporata
