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Obtineti 200g solutie HCl de concentratie 9%, pornind de la o solutie de 36% HCl cu densitatea egala cu 1, 18 g/cm³.

Răspuns :

msi = ms     ci = 36%  ⇒   md = 0,36ms
m apa = x 
-----------------
msf = ms + x = 200g     md = 0,36ms      cf = 9%
36ms/(ms + x) = 9   4ms = ms + x      3ms = x
ms + 3ms = 200g      ms = 50g     m apa = 150g   
Vs = 50/1,18 = 42,37cm³
 

msf=200g
cf=9%
ci=36%
ρ=1,18g/cm3
ms1=?
V=?
md=c*msf/100=9*200/100=18 g
ms=md*100/c=18*100/36=50g
ρ=ms/Vs
Vs=ms/ρ=50 g/1.18g/cm3=42,37cm3