8/.
ZnSO4*7H2O
161 + 7x18 = 287 g/mol
287 g cristal. ............ 161 g ZnSO4 anhidru
50 g ............................. a = 28,05 g sare anhidra
ms final = m.crsialohidrat + m.apa
= 50 + 150 = 200 g
md = 28,05 g
c% = 28,05x100/200 = 14% => b).
7/.
ms1 = 80 g , c1% = 20%
ms2 = 120 g , c2% = 30%
stim ca c% = mdx100/ms
avem ms.final = 80+120 = 200 g
md1 = ms1xc1/100 = 80x20/100 = 16 g
md2 = ms2xc2/100 = 120x30/100 = 36 g
=> md.final = 16+36 = 52 g
=> c.f.% = md.finalx100/ms.final
= 52x100/200 = 28%
