1.
ms.final = 300 g, c.final = 20%
c% = mdx100/ms
=> md = msxc100/c%
= 300x20/100 = 60 g zahar dizolvat
2.
ms1 = 400g , c1 = 10%
ms2 = ? g , c2 = 20%
notam cu a = masa de apa evaporata
ms2 = ms1 - a = 400-a
md = ms1xc1/100 = 400x10/100 = 40 g
c2 = mdx100/ms2
20 = 40x100/(400-a)
=> a = 4000/20 = 200 g apa evaporata
facem proba:
md= 40g , ms2 = 400-200 = 200 g
=> c2 = 40x100/200 = 20%, deci verifica calculele de mai sus
3.
ms1= 300g , c1= 10%
ms2= 400g , c2= 30%
md1 = ms1xc1/100 = 300x10/100 = 30 g
md2 = ms2xc2/100 = 400x30/100 = 120 g
md.final = md1+md2 = 30+120 = 150 g
ms.final = ms1+ms2= 300+400 = 700 g
=> c%final = md.finalx100/ms.final
= 150x100/700 = 21,43%
4.
Vs= 500 cm3 , c% = 40% , p = 1,22 g/cm3
p = ms/Vs => ms = pxVs = 500x1,22 = 610 g sol.
md = msxc%/100= 610x40/100 = 244 g
=> m.apa = ms-md = 610 - 244 = 366 g apa
