Question

7.Concentratia procentuala a unei solutii de sare , obtinuta prin dizolvarea a 50 g substanta in 400g apa este: a)8,88% b)11,11% c)12,50% d)50%

8.Masa de acid clorhidric continuta in 200mL solutie de concentratie 8,5% si p=1,04 g/mL este: a)1,70 g b)1,78 g c)17 g d)17,68

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Answer 1

md=50g
mH2O=400 g
c=?
ms=md+mapă=50 g+400 g=450 g
c=md/ms*100=50 g/450 g*100=11,11 %
8.Vs=200 ml
C=8,5 %
ρ1,04 g/ml
mHCl=?
ρ=m/v=> ms=ρ*V=1.04 g/ml *200ml=208 g
C=md/ms*100
md=C*ms/100=8,5*208/100=17,68